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Names ____________________________________________________________
Famous Comets
(an activity from NASA’s STARDUST Mission: Think SMALL in a Big Way Guide)
This activity has two parts. In the first part, you will research the significance of a
specific comet. In the second part, you will write a story based on the facts surrounding
your comet.
You will work in teams of two to four students.
Part, the First
Comet Research Team Worksheet
Team Roles
Decide which team member will perform each of the following roles (if you don’t have
four in your group, one or two members can do two jobs):
 Recorder: Records the results of the team’s research.
 Computer Operator: Uses the computer to navigate the Internet and print out
any essential materials.
 Literary Supervisor: Records team’s input for the story.
 Reporter: Presents the team’s story to the rest of the class.
Using the Internet, answer the questions on the next page. Have the recorder write
down what the team learns. Each of the computers in the classroom has a folder called
“Comets” with websites that will help you select your comet and find out more
information about that comet.
We have selected Comet _____________________________________________
1. What makes this comet unique?
2. How long is this comet’s period?
3. What major events in history have happened when the comet has appeared?
4. How did this comet change the way astronomers think about comets or the
Solar System?
5. Who discovered the comet? From what country was the discoverer? Was the
discoverer a professional or amateur astronomer?
6. Print out a picture of the comet. Label its coma, gas tail, dust tail, and nucleus (if
7. What was the most recent great comet?
8. What comets will appear in the night sky over the next three years?
Part, the Second
Using the information about your comet, you will write a story based on the facts
surrounding your comet.
Use the following writing prompts to help your team write a two-page story about your
comet. Have the Literary Supervisor write the story as the rest of the team provides
ideas and suggestions. Base your story on facts and science concepts.
Here are some suggestions.
 Imagine you are a reporter writing a headline story about sighting this comet.
 Imagine that you belong to another culture in another century when your comet
appears. Describe what you see, what you think it is, and how you feel.
 Imagine you are an amateur astronomer watching the night sky when you think you
discover a comet. How do you feel? Whom do you tell?
 Imagine you are the comet. Talk about where you would travel during your entire
 Think of your own story!
Illustrate your story with the photo you printed of your comet. Make sure that its parts
are labeled.
Famous Comets!
On July 23, 1995, an unusually large
and bright comet was seen outside of
Jupiter's orbit by Alan Hale of New
Mexico and Thomas Bopp of Arizona.
Careful analysis of Hubble Space
Telescope images suggested that its
intense brightness was due to its
exceptionally large size. While the
nuclei of most comets are about 1.6
to 3.2 km (1 to 2 miles) across,
Hale-Bopp's was estimated to be 40
km (25 miles) across. It was visible
even through bright city skies, and
may have been the most viewed
comet in recorded history. Comet
Hale-Bopp holds the record for the
longest period of naked-eye visibility:
an astonishing 19 months. It will not
appear again for another 2,400 years.
This comet was first seen in July 1862 by
American astronomers Lewis Swift and
Horace Tuttle. As Comet Swift-Tuttle moves
closer to the Sun every 120 years, it leaves
behind a trail of dust debris that provides the
ingredients for a spectacular fireworks
display seen in July and August. As Earth
passes through the remnants of this dust
tail, we can see on a clear night the Perseid
meteor shower. Comet Swift-Tuttle is noted
as the comet some scientists predicted
could one day collide with Earth because the
two orbits closely intercept each other. The
latest calculations show that it will pass a
comfortable 24 million km (15 million miles)
from Earth on its next trip to the inner Solar
On January 30, 1996, Yuji Hyakutake
(pronounced "hyah-koo-tah-kay"), an
amateur astronomer from southern
Japan, discovered a new comet using
a pair of binoculars. In the spring of
that year this small bright comet with
1 of 3
1/23/2011 4:46 PM
Famous Comets!
2 of 3
a nucleus of 1.6 to 3.2 km (1 to 2
miles) made a close flyby of Earth —
sporting one of the longest tails ever
observed. The Hubble Space
Telescope studied the nucleus of this
comet in great detail. This is not
Comet Hyakutake's first visit to the
inner Solar System. Astronomers
have calculated its orbit and believe it
was here about 8,000 years ago. Its
orbit will not bring it near the Sun
again for about 14,000 years.
Comet Halley is perhaps the most famous
comet in history. It was named after British
astronomer Edmund Halley, who calculated
its orbit. He determined that the comets
seen in 1531 and 1607 were the same
objects that followed a 76-year orbit.
Unfortunately, Halley died in 1742, never
living to see his prediction come true when
the comet returned on Christmas Eve in
1758. Each time this comet's orbit
approaches the Sun, its 15-km (9-mile)
nucleus sheds about 6 m (7 yards) of ice
and rock into space. This debris forms an
orbiting trail that, when falling to Earth, is
called the Orionids meteor shower. Comet
Halley will return to the inner Solar System
in the year 2061.
Between July 16 and July 22, 1994, more than 20 fragments of Comet
Shoemaker-Levy 9 collided with the planet Jupiter. Astronomers Carolyn and
Eugene Shoemaker and David Levy discovered the comet in 1993. The Hubble
Space Telescope took many spectacular pictures of this event as the comet's
pieces crashed into Jupiter's southern hemisphere. It was the first collision of two
Solar System bodies ever to be recorded. The impacts created atmospheric
plumes many thousands of kilometers high that showed hot "bubbles" of gas with
large dark "scars" covering the planet's sky.
1/23/2011 4:46 PM
Amazing Space- Fast Facts: Comet Hale-Bopp
1 of 2
Hubble's 20th
Capture the cosmos > Comets > Dig deeper (cont'd) > Fast Facts:
Comet Hale-Bopp
The Star
Hale-Bopp has a very large nucleus.
(Most comet nuclei measure only 1.6 to
3.2 km, or 1-2 miles, in diameter.) It
could be seen in the sky for a record 19
months — from May 1996 to November
1997 — and was visible through the
bright skies of cities.
About the same age as the Sun: 4.5
billion years
the cosmos
Outer solar system — Oort Cloud
Avg. distance
from the Sun
It has a highly elongated orbit that
takes it very close to the Sun and then
flings it out into the outer solar system,
well past the orbit of Pluto.
The diameter of the nucleus has been
estimated to be 40-80 km (25-50
Not determined
around the
2,392 Earth years
Mission 4
by topic
(Image courtesy
of Alessandro
Capture the cosmos > Comets > Dig deeper (cont'd) > Fast Facts:
Comet Hale-Bopp
1/23/2011 4:51 PM
Comet Hale-Bopp - Bob the Alien's Tour of the Solar System
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What are Comets?
Halley's Comet
Comet Hale-Bopp
Halley's Comet Facts
What are Comets?
Halley's Comet
Comet Hale-Bopp
Ten Facts About Halley's Comet
The view of the night sky from Earth is very familiar. On a clear night, you know that you will be able to look into the sky
and see the Moon and lots of stars. Sometimes though, the Moon and stars are joined by other objects. If you looked into the
sky on an evening early in 1997, you may have been able to see what looked like a star which had been smudged. In fact,
this smudged star was a comet, one of the brightest comets visible from Earth for many years. It was named Comet
Hale-Bopp and remained visible from Earth for 19 months, being at its brightest and clearest during the first half of 1997.
Comets are balls of ice, dust and gas which travel in elliptical orbits around the Sun. At their most distant, they are invisible.
However, when they get closer to the Sun, they begin glowing, forming a coma and tails as dust and gas is burnt off the
comet. It is only when they have begun glowing that they become visible from Earth with telescopes. This means that they
usually only get discovered two or three months before they actually get close to Earth. However, Hale-Bopp was different. it
was discovered almost two years before it became a prominent feature in the night sky.
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It was a summer's evening in July 1995 when two astronomers in different parts of America happened to be observing the
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same part of the sky. Alan Hale is a professional astronomer and was working at his observatory in New Mexico on the
evening of 22nd July. He was actually observing other comets, but while waiting for one previously discovered comet to come
into view, he turned his telescope to a group of stars called M70 (a globular cluster). At a similar time, Tom Bopp, an
amateur astronomer at a "star party" in Phoenix (a gathering for astronomers to observe the stars together!), was also
observing the M70 globular cluster. Both astronomers noticed a small fuzzy object in a place where there shouldn't be a
fuzzy object. Alan Hale suspected the object may be a comet, but had to check it hadn't already been discovered. He referred
to his big comet catalogue and noticing it wasn't in there, he emailed the Central Bureau for Astronomical Telegrams. He
returned to his discovery and noticed that the object had moved against the starry backdrop, confirming that it definitely was
a comet. He then sent a second email. When Tom Bopp observed the object, he called over some friends. They watched the
object move against the stars in the background and, realising he had discovered a comet, Bopp also got in touch with the
Central Bureau for Astronomical Telegrams to inform them of this. Because both people discovered the comet at about the
same time, it was named after both of them, hence the name Comet Hale-Bopp.
When the comet was discovered, it was about as far away from
Earth as Jupiter is. The comet doesn't orbit on the same path as the
planets. In the diagram to the left, the orbits of the four inner
planets and Jupiter can be seen. The path that Hale Bopp takes can
also be seen.. Because Hale-Bopp was discovered when it was so far
away from Earth, there was a great deal of anticipation that when it
got closer, it would be very bright. Halley's Comet, which last visited
in 1986, has a nucleus of 20km. The nucleus of Hale Bopp is 40km,
much larger than most comets.
After discovery, the comet continued on its journey towards the Sun. As it got closer, its tail got larger and became easier to
spot. On 20th May 1996, Terry Lovejoy of Queensland, Australia became the first person to spot the comet with the naked
eye. It would have still been very faint from Earth, but as the months went on, more and more people reported sightings of
the comet without the assistance of a telescope or binoculars. Throughout the summer of 1996, Comet Hale-Bopp actually
became dimmer, leading scientists to believe that it had fizzled out. However, it began getting brighter again and in early
1997, it was clearly visible from Earth. The comet came closest to Earth on 22nd March 1997 (at a distance of over 122
million kilometres) and closest to the Sun on 1st April 1997. After reaching the Sun and going behind it the comet was
thrown back out and continued its journey away from the Sun, becoming less and less visible from Earth. It is estimated that
it will return in 2,300 years, in the year 4534! The comet would have last been visible 4,200 years ago. The reason its next
visit is sooner than its last visit is because in March 1997, Comet Hale-Bopp passed within the gravitational influence of
Jupiter, shortening the length of time it takes to complete an orbit. The furthest the comet will go from the Sun now is 371
AU (Astronomical Units). 1 AU is approximately the distance Earth is from the Sun, so Hale-Bopp will go 371 times as far
1/23/2011 4:59 PM
Comet Hale-Bopp - Bob the Alien's Tour of the Solar System
2 of 2
from the Sun as Earth is.
Comet Hale-Bopp spent four months as a regular clear object in the night sky. it is estimated that 81% of Americans saw it,
and the comet became the most photographed comet in the history of, er, comet photography. I suppose this isn't such a
great claim when you realise that the last great comet was in 1811 before cameras were even invented! The comet was
visible from Earth with the naked eye for a record breaking 19 months. The comet was very much a comet of the Internet
Boom of the late 1990s. The fast increase in Internet users meant that people all over the world could share information
about sightings, pictures, etc. with each other. The original Comet Hale-Bopp website became NASA's first website to achieve
1 million hits in one day. If only this website was around back then - it might have had a visit or two!
Comet Hale-Bopp also had a darker side. Throughout history, comets have been seen as omens; a sign that something was
going to happen. An early image of the comet was taken by an amateur astronomer which showed a mysterious object which
looked like it was following the comet. This object didn't match up with any stars that should have been in the area, so the
astronomer contacted a radio show stating that Hale-Bopp was being accompanied by a Saturn-Like Object. A cult calling
themselves Heaven's Gate believed that this Saturn-like object could be a UFO. 39 members of the cult killed themselves,
believing that their spirits would be taken to another world by this UFO. That's what happens when you watch too much
X-Files! Analysis of the image proved that the object was in fact a star.
For most of us, Comet Hale-Bopp was simply a once-in-a lifetime opportunity to see a comet. It is now hundreds of millions of
miles away from us and has much further to go before it even starts to return to our part of the Solar System. Of course,
there may be other comets about to visit us, and some may be even brighter than Hale-Bopp. Comets are mysterious
objects. Unless they have been previously discovered and visit regularly (like Halley's Comet), we don't know they exist until
they get very close to us. And even when they have been discovered, it isn't until they get even closer that we find out just
how spectacular it is.
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1/23/2011 4:59 PM
How Comet Hyakutake B2 Was Discovered
1 of 2
March 29, 1996
I am a 45-year old amateur astronomer from Kagoshima, Japan. My name, Hyakutake, means "100 samurai,
or chivalry," in Japanese. It is not a very common name in Japan.
I graduated from the Art Department at Kyushu Industry University, where I majored in photography.
I live in the village of Hayato, in the southernmost prefecture located 600 miles southwest of Tokyo on the
island of Kyushu. I lived in Fukuoka for many years, but moved to Kagoshima because the skies are much
clearer there.
I have been married for 15 years, and have two sons, ages 10 and 13. I am the only one in my family whose
hobby is searching for comets. My younger son likes the television show, "The X-Files."
I've been interested in comets since I was 15 years old, after I heard of the Japanese Comet Ikeya-Seki which
appeared in 1965. My interest in astronomy has increased steadily since then. I wanted to discover a comet
that had a very far orbit.
Although I started searching for comets about seven years ago when I lived in Fukuoka, I have concentrated
my efforts more intensely since I moved to Kagoshima two years ago.
Since last July, I have been avidly searching the night sky for comets from 2 a.m. to 5 a.m., about four nights
a month. I want to continue searching for comets while my eyesight is reasonably good.
Many people have asked me how I discovered Comet Hyakutake. I live in the countryside and travel to a
rural mountain top area about 10 miles from my home to get a better view of the night sky. (Before I was
married, I enjoyed mountain climbing.)
Actually, I discovered two comets. I spotted the first one at 5:40 a.m. on December 26. I wasn't sure it was a
comet, but I reported the sighting anyway. This first comet is still there, but it's not very bright.
A month later, I went back to the area to take photos of the first comet. I looked l up at the sky where it
should have been at that point in its path. However, that particular spot was filled with clouds. I tried to find
an area in the sky that was unobscured. The clouds led me back to the same spot in the sky where I had
originally found the first comet, but it didn't make sense that it would be there. That is when I discovered the
second Comet Hyakutake, the one the media now refers to as "The Comet of the Century."
I've been asked about 75 times how I felt when I discovered this comet. Actually, I was feeling a bit confused.
My reaction was somewhat complicated, since I had originally intended to go to the viewing spot to take a
picture of my first comet. I found the second comet in the same area as the first one, near the constellations of
Libra and Hydra.
1/23/2011 5:03 PM
How Comet Hyakutake B2 Was Discovered
2 of 2
I discovered Comet Hyakutake at 4:50 in the morning, and usually a person can report a comet after 8 a.m.,
but I decided to take some photos of the comet, using my camera with telephoto lenses, and got them
developed. It wasn't until 11 a.m. that I called the National Astronomy Observatory in Tokyo to report my
new comet.
I followed the formal procedure of gathering data and documenting my new comet discovery with photos.
Then two other amateur astronomers in Japan recognized the comet.
It's interesting that my discovery wasn't reported very widely by the Japanese media until recently. The first
media reports were from London. Then the American press became very interested. Now the Japanese media
is covering the comet story. My wife can't make phone calls because the phone is always ringing.
I'm happy that this Comet Hyakutake was the second one I discovered, because it wasn't mere coincidence.
This proved to me that my method of searching for comets is working, and I will continue to look for them.
I use high-powered, field binoculars with 6-inch lenses, mounted on a stand. This is the only equipment I own.
Comet Hyakutake has the longest tail that I have ever observed, although the new Hubble images show that
this comet is breaking into fragments.
I am a bit perplexed by all the attention paid to me, when it is the comet that deserves the credit.
Comet 1996 B2 Hyakutake Home Page
1/23/2011 5:03 PM
Comet Hyakutake - Wikipedia, the free encyclopedia
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From Wikipedia, the free encyclopedia
C/1996 B2 (Hyakutake)
Comet Hyakutake (Japanese
pronunciation: [çʲakɯ̥take], formally designated
C/1996 B2) is a comet, discovered on January 31,
1996,[1] which passed very close to Earth in March
of that year. It was dubbed The Great Comet of
1996; its passage near the Earth was one of the
closest cometary approaches of the previous 200
years. Hyakutake appeared very bright in the night
sky and was widely seen around the world. The
comet temporarily upstaged the much anticipated
Comet Hale-Bopp, which was approaching the inner
Solar System at the time.
Scientific observations of the comet led to several
discoveries. Most surprising to cometary scientists
was the first discovery of X-ray emission from a
comet, believed to have been caused by ionised solar
wind particles interacting with neutral atoms in the
coma of the comet. The Ulysses spacecraft
unexpectedly crossed the comet's tail at a distance of
more than 500 million km from the nucleus, showing
that Hyakutake had the longest tail known for a
Hyakutake is a long-period comet. Before its most
recent passage through the Solar System, its orbital
period was about 17,000 years, but the gravitational
influence of the giant planets has increased this
period to 72,000 years.
1 Discovery
2 Orbit
3 The comet passes the Earth
4 Perihelion and afterwards
5 Scientific results
5.1 Spacecraft passes through the tail
5.2 Composition
5.3 X-ray emission
5.4 Nucleus size and activity
Comet Hyakutake captured by the Hubble Space Telescope on
April 4, 1996, with an infrared filter.
Discovery and designation
Discovered by
Yuji Hyakutake
Discovery date
31 January 1996[1]
Great Comet of 1996
Alternate name(s)[note 1]
Orbital characteristics[2]
Epoch 2450400.5
Semi-major axis
Orbital period
Longitude of ascending node
Argument of peri
4367.87 AU
0.2301987 AU
2184.05 AU
102070 a
Physical characteristics
Sidereal rotation
Absolute magnitude (H)
4.2 km[3]
6 hours
1. ^ Minor Planet Designations (
6 References
7 External links
1/23/2011 5:06 PM
Comet Hyakutake - Wikipedia, the free encyclopedia
2 of 7
The comet was discovered on January 31, 1996,[1] by Yuji Hyakutake, an amateur astronomer from southern
Japan.[4] He had been searching for comets for years and had moved to Kagoshima Prefecture partly for the
dark skies in nearby rural areas. He was using a powerful set of binoculars with 150 mm (6 inch) objective
lenses to scan the skies on the night of the discovery.[5]
This comet was actually the second Comet Hyakutake; Hyakutake had discovered comet C/1995 Y1 several
weeks earlier.[6] While re-observing his first comet (which never became visible to the naked eye) and the
surrounding patch of sky, Hyakutake was surprised to find another comet in almost the same position as the first
had been. Hardly believing a second discovery so soon after the first, Hyakutake reported his observation to the
National Astronomical Observatory of Japan the following morning.[7] Later that day, the discovery was
confirmed by independent observations.
At the time of its discovery, the comet was shining at magnitude 11.0 and had a coma approximately
2.5 arcminutes across. It was approximately 2 astronomical units (AU) from the Sun.[8] Later, a pre-discovery
image of the comet was found on a photograph taken on January 1, when the comet was about 2.4 AU from the
Sun and had a magnitude of 13.3.[9]
When the first calculations of the comet's orbit were made, scientists realized that it was going to pass just
0.1 AU from the Earth on 25 March.[10] Only four comets in the previous century had passed closer.[11] Comet
Hale-Bopp was already being discussed as a possible "great comet"; the astronomical community eventually
realised that Hyakutake might also become spectacular because of its close approach.
Moreover, the comet's orbit showed that it had last returned to the inner Solar System approximately
17,000 years earlier. Because the comet had probably passed close to the Sun several times before,[9] the
approach in 1996 would not be a maiden arrival from the Oort cloud, a place where comets with orbital periods
of millions of years come from. Comets entering the inner Solar System for the first time may brighten rapidly
before fading as they near the Sun, as a layer of highly volatile material evaporates. This was the case with
Comet Kohoutek in 1973; it was initially touted as potentially spectacular, but only appeared moderately bright.
Older comets show a more consistent brightening pattern. Thus, all indications pointed that Comet Hyakutake
would be bright.
Besides approaching close to the Earth, the comet would also be visible throughout the night to northern
hemisphere observers at its closest approach because of its path, passing very close to the pole star. This would
be an unusual occurrence, because most comets are close to the Sun in the sky when the comets are at their
brightest, leading to the comets appearing in a sky not completely dark.
1/23/2011 5:06 PM
Comet Hyakutake - Wikipedia, the free encyclopedia
3 of 7
Hyakutake became visible to the naked eye in early March 1996.
By mid-March, the comet was still fairly unremarkable, shining at
4th magnitude with a tail about 5 degrees long. As it neared its
closest approach to Earth, it rapidly became brighter, and its tail
grew in length. By March 24, the comet was one of the brightest
objects in the night sky, and its tail stretched 35 degrees. The comet
had a notably bluish-green colour.[9]
The closest approach occurred on 25 March. Hyakutake was
moving so rapidly across the night sky that its movement could be
detected against the stars in just a few minutes; it covered the
The comet on the evening of its closest
diameter of a full moon (half a degree) every 30 minutes. Observers
approach to Earth on 25 March 1996.
estimated its magnitude as around 0, and tail lengths of up to
80 degrees were reported.[9] Its coma, now close to the zenith for
observers at mid-northern latitudes, appeared approximately 1.5 to 2 degrees across, roughly four times the
diameter of the full moon.[9] Even to the naked eye, the comet's head appeared distinctly green, due to strong
emissions from diatomic carbon (C2).
Because Hyakutake was at its brightest for only a few days, it did not have time to permeate the public
imagination in the way that Comet Hale-Bopp did the following year. Many European observers in particular
did not see the comet at its peak because of unfavourable weather conditions.[9]
After its close approach to the Earth, the comet faded to about 2nd
magnitude. It reached perihelion on May 1, 1996, brightening again and
exhibiting a dust tail in addition to the gas tail seen as it passed the Earth.
By this time, however, it was close to the Sun and was not seen as easily. It
was observed passing perihelion by the SOHO Sun-observing satellite,
which also recorded a large coronal mass ejection being formed at the same
time. Its distance from the Sun at perihelion was 0.23 AU, well inside the
orbit of Mercury.[12]
After its perihelion passage, Hyakutake faded rapidly and was lost to
naked-eye visibility by the end of May. Its orbital path carried it rapidly into
the southern skies, but following perihelion it became much less monitored.
The last known observation of the comet took place on November 2.[13]
Hyakutake had passed through the inner Solar System approximately
17,000 years ago; gravitational interactions with the gas giants during its
1996 passage stretched its orbit greatly, and fits to the comet's orbit
predicted it will not return to the inner Solar System again for approximately
72,000[9] to 114,000 years.[14]
The SOHO satellite captured
this image of Hyakutake as it
passed perihelion, with a
nascent coronal mass ejection
also visible to the left of the
Spacecraft passes through the tail
1/23/2011 5:06 PM
4 of 7
The Ulysses spacecraft made an unexpected pass through the tail of the comet on May 1, 1996.[15] Evidence of
the encounter was not noticed until 1998. Astronomers analysing old data found that Ulysses' instruments had
detected a large drop in the number of protons passing, as well as a change in the direction and strength of the
local magnetic field. This implied that the spacecraft had crossed the 'wake' of an object, most likely a comet;
the object responsible was not immediately identified.
In 2000, two teams independently analyzed the same event. The magnetometer team realized that the changes in
the direction of the magnetic field mentioned above agreed with the "draping" pattern expected in a comet's ion,
or plasma tail. The magnetometer team looked for likely suspects. No known comets were located near the
satellite, but looking further afield, they found that Hyakutake, 500 million km away, had crossed Ulysses'
orbital plane on April 23, 1996. The solar wind had a velocity at the time of about 750 km/s, at which speed it
would have taken eight days for the tail to be carried out to where the spacecraft was situated at 3.73 AU,
approximately 45 degrees out of the ecliptic plane. The orientation of the ion tail inferred from the magnetic
field measurements agreed with the source lying in Comet Hyakutake's orbital plane.[16]
The other team, working on data from the spacecraft's ion composition spectrometer, discovered a sudden large
spike in detected levels of ionised particles at the same time. The relative abundance of chemical elements
detected indicated that the object responsible was definitely a comet.[17]
Based on the Ulysses encounter, the comet's tail is known to have been at least 570 million km
(360 million miles; 3.8 AU) long. This is almost twice as long as the previous longest-known cometary tail, that
of the Great Comet of 1843, which was 2.2 AU long.
Terrestrial observers found ethane and methane in the comet, the first time either of these gases had been
detected in a comet. Chemical analysis showed that the abundances of ethane and methane were roughly equal,
which may imply that its ices formed in interstellar space, away from the Sun, which would have evaporated
these volatile molecules. Hyakutake's ices must have formed at temperatures of 20 K or less, indicating that it
probably formed in a denser than average interstellar cloud.[18]
The amount of deuterium in the comet's water ices was determined through spectroscopic observations.[19] It
was found that the ratio of deuterium to hydrogen (known as the D/H ratio) was about 3 × 10−4, which
compares to a value in Earth's oceans of about 1.5 × 10−4. It has been proposed that cometary collisions with
Earth might have supplied a large proportion of the water in the oceans, but the high D/H ratio measured in
Hyakutake and other comets such as Hale-Bopp and Halley's Comet have caused problems for this theory.
1/23/2011 5:06 PM
Amazing Space- Fast Facts: Comet Halley
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Teaching tools > Comets > Overview: Comet Halley facts > Fast
Facts: Comet Halley
Teaching tools
Halley is perhaps the most famous
comet in history. This is the comet that
proved correct Edmund Halley's
prediction that it would reappear. It is
responsible for depositing the debris
that, when falling through Earth's
atmosphere, causes the Orionid meteor
About the same age as the Sun: 4.5
billion years
Outer solar system — Kuiper belt
Avg. distance
from the Sun
It has a highly elongated orbit that
takes it very close to the Sun and then
flings it out into the outer solar system,
well past the orbit of Pluto.
The size of the nucleus has been
estimated to be 15 km x 7 km x 7 km
(or 9 mi x 4 mi x 4 mi).
1.7 x 1015 kilograms
around the
76 Earth years
(Image courtesy
of NASA)
Teaching tools > Comets > Overview: Comet Halley facts > Fast
Facts: Comet Halley
1/23/2011 5:47 PM
Comet Halley
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Spacecraft that have visited Halley's Comet
Halley's [HAL-lee] Comet has been know since at least 240 BC and possibly since 1059 BC.
Its most famous appearance was in 1066 AD when it was seen right before the Battle of
Hastings. It was named after Edmund Halley, who calculated its orbit. He determined that
the comets seen in 1531 and 1607 were the same object that followed a 76-year orbit.
Unfortunately, Halley died in 1742, never living to see his prediction come true when the
comet returned on Christmas Eve 1758.
Halley's Comet put on bright shows in 1835 and in 1910. Then in 1984 and 1985, five
spacecraft from the USSR, Japan and Europe were launched to make a rendezvous with
Halley's Comet in 1986. One of NASA's deep space satellites was redirected to monitor the
solar wind upstream from Halley. Only three comets have ever been studied by spacecraft.
Comet Giacobini-Zinner was studied in 1985, Comet Halley in 1986, and CometGriggSkjellerup on July 10th, 1992. The nucleus of Halley is ellipsoidal in shape and measures
approximately 16 by 8 by 8 kilometers (10 by 5 by 5 miles).
Halley's Comet Statistics
Perihelion distance: 0.587 AU
Orbital eccentricity: 0.967
Orbital inclination: 162.24°
Orbital period: 76.0 years
Next perihelion: 2061
Diameter: 16 x 8 x 8 km
Animation of Halley's Comet
Animation of Halley's comet from Giotto pictures. (Courtesy A.Tayfun Oner)
Views of Halley's Comet
Comet Halley in False Color
This image of Halley's Comets was taken during its 1986 appearance. False-color digital enhancement was
used to permit measurement of slight brightness differences. (Copyright Calvin J. Hamilton)
Giotto Mosaic of Halley's Comet
This image is a mosaic of 8 images taken by the Giotto spacecraft during the Halley encounter on March 13,
1/23/2011 5:16 PM
Halley's comet
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Brought to you by the National Earth Science Teachers Association
This image of the nucleus of
Halley's comet comes from the
Giotto spacecraft.
Click on image for full size
Halley's comet
Halley's comet is named after Edmond G. Halley who was the first to suggest that comets were
natural phenomena of the solar system, in orbit around the Sun. He suggested that a certain
comet was a regular visitor, returning every 76 years, and was, in fact, the same one which had
been observed since 240 BC, but in particular in the years 1531, 1607, and 1682, dates which for
him were recent history. In 1682 he predicted the comet would return again in 1758, and sure
enough, the comet arrived in March 1759. Halley's comet made a particularly bright
appearance in 1910. It also was recorded in a famous ancient tapestry after its 1066
For hundreds of years humankind has wondered what the nucleus of Halley's comet was really
like. This wonderful picture from the Giotto spacecraft gives us the answer. In this picture, the
Sun is on the left. Three jets can be seen blowing molecules toward the Sun. A crater can also
be seen in the middle right. This image shows that evaporation occurs along specific portions of
the comet. Data taken by a suite of spacecraft suggests that the comet is mostly made of ice.
Halley's comet is next scheduled to return in 2062.
Last modified December 6, 2000 by Jennifer Bergman.
News Flash!
1/23/2011 5:17 PM
Comet West - Wikipedia, the free encyclopedia
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From Wikipedia, the free encyclopedia
There is another long-period comet West: C/1978 A1 (a.k.a. 1977 IX, 1978a).
Comet West formally designated C/1975 V1, 1976 VI, and
1975n, was a spectacular comet, sometimes considered to
qualify for the status of "great comet".
C/1975 V1 (West)
1 Discovery
2 Breakup
3 Nomenclature
4 References
It was discovered photographically by Richard M. West, of the
European Southern Observatory, on August 10, 1975, and
reached peak brightness in March 1976, attaining a brightness of
-3 at perihelion. During peak brightness, observers reported that
it was bright enough to study during full daylight.
Despite its spectacular appearance, Comet West went largely
unreported in the popular media. This was partly due to the
relatively disappointing display of Comet Kohoutek in 1973,
which had been widely predicted to become extremely
prominent: scientists were wary of making predictions that might
raise public expectations.[1]
Discovered by:
Richard M. West
Discovery date:
August 10, 1975
C/1975 V1, 1976 VI,
Orbital characteristics A
Aphelion distance:
Perihelion distance:
Semi-major axis:
Orbital period:
Last perihelion:
13560 AU
0.58 AU
6,780.20 AU
558,306.4201 a
February 25, 1976
The comet has an estimated orbital period of 558,000 years.
During the passage of Comet West into the inner solar system, possibly for the first time in 500,000 years, its
nucleus was observed to split into four fragments as it passed within 30 million km of the Sun.
The first report of the split came around 7 March 1976 12:30UT, when reports were received that the comet had
broken into two pieces. Astronomer Steven O'Meara, using the 9-inch Harvard Refractor, reported that two
additional fragments had formed on the morning of 18 March.
The fragmentation of the nucleus was, at the time, one of very few comet breakups observed, one of the most
notable previous examples being the Great Comet of 1882, a member of the Kreutz Sungrazing 'family' of
comets. More recently, comets Schwassmann-Wachmann-3 (73/P), C/1999 S4 LINEAR, and 57/P du
Toit-Neujmin-Delporte, have been observed to disintegrate during their passage close to the Sun.
1/23/2011 5:35 PM
Comet Encke - Wikipedia, the free encyclopedia
From Wikipedia, the free encyclopedia
Comet Encke or Encke's Comet (official designation:
2P/Encke) is a periodic comet that completes an orbit of the
sun once every three years — the shortest period of any
known comet. It was first recorded by Pierre Méchain in
1786, but it was not recognized as a periodic comet until
1819 when its orbit was computed by Johann Franz Encke;
like Halley's Comet, it is unusual in being named after the
calculator of its orbit rather than its discoverer.
1 Discovery
2 Characteristics
3 Observations
4 Meteor showers
5 Effects on Earth
6 Importance in the scientific history of
luminiferous aether
7 See also
8 References
9 External links
Discovered by:
Discovery date:
Pierre Méchain
1786 I; 1795; 1805;
1819 I; 1822 II; 1825 III;
1829; 1832 I; 1835 II;
1838; 1842 I; 1845 IV
Orbital characteristics A
As its official designation implies, Encke's Comet was the
first periodic comet discovered after Halley's Comet
(designated 1P/Halley). Its orbit was calculated by Johann
Franz Encke, who, through laborious calculations was able to
link observations of comets in 1786 (designated 2P/1786
B1), 1795 (2P/1795 V1), 1805 (2P/1805 U1) and 1818
(2P/1818 W1) to the same object. In 1819 he published his
conclusions in the journal Correspondance astronomique,
and predicted correctly its return in 1822 (2P/1822 L1).
September 22, 2006 (JD
Aphelion distance: 4.11 AU
Perihelion distance: 0.3302 AU
Semi-major axis:
2.2178 AU
Orbital period:
3.30 a
Last perihelion:
6 August 2010[1]
Next perihelion:
21 November 2013[1]
The diameter of the nucleus of Encke's Comet is 4.8 km.[2]
Comets are in unstable orbits that evolve over time due to perturbations and outgassing. Given Encke's low
orbital inclination near the ecliptic and brief orbital period of 3 years, the orbit of Encke is frequently perturbed
by the inner planets.[3]
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1/23/2011 5:38 PM
The failed CONTOUR mission was launched to study this comet, and also Schwassmann-Wachmann 3.
On April 20, 2007, the tail of Comet Encke was observed to be temporarily torn off by magnetic field
disturbances caused by a Coronal Mass Ejection: a blast of solar particles from the sun.[4] The tail grew back
due to the continuous shedding of dust and gas by the comet.[5]
Comet Encke is believed to be the originator of several related meteor
showers known as the Taurids (which are encountered as the Northern
and Southern Taurids across November, and the Beta Taurids in late
June and early July).[6][7]
Near-Earth object 2004 TG10 may be a fragment of Encke.[8]
More than one theory has associated Encke's Comet with impacts of
cometary material on Earth, and with cultural significance.
A Spitzer image of Encke and its
debris trail in infrared light. Credit:
(NASA/JPL-Caltech/University of
The Tunguska event of 1908, probably caused by the impact of a
cometary body, has also been postulated by Czechoslovakian astronomer
Ľubor Kresák as a fragment of Comet Encke.[9]
A theory
holds that
the ancient
symbol of
the swastika appeared in a variety of cultures across
the world at a similar time, and could have been
inspired by the appearance of a comet from head on,
as the curved jets would be reminiscent of the
swastika shape (see Comets and the swastika motif).
Comet Encke has sometimes been identified as the
comet in question. In their 1982 book Cosmic
A Han Dynasty silk comet atlas, featuring drawings of
Serpent (page 155) Victor Clube and Bill Napier
comets believed by Victor Clube and Bill Napier to be
reproduce an ancient Chinese catalogue of cometary
related to the breakup of Encke's Comet in the past
shapes from the Mawangdui Silk Texts, which
includes a swastika-shaped comet, and suggest that some of the comet drawings were related to the breakup of
the progenitor of Encke and the Taurid meteoroid stream. Fred Whipple in his The Mystery of Comets (1985,
page 163) points out that Comet Encke's polar axis is only 5 degrees from its orbital plane: such an orientation is
ideal to have presented a pinwheel like aspect to our ancestors when Encke was more active.
Comet 73P/Schwassmann-Wachmann 3
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Contents | What's New | Image Index | Copyright | Puzzles | Posters | Search |
Table of Contents
Comet Introduction
Comet Historical Background
Comet 73P/Schwassmann Wachmann 3
Comet Borrelly
Halley's Comet
Shoemaker-Levy 9
Shoemaker-Levy 9
Shoemaker-Levy 9 Impact
Hubble PR - Collision Results
Comet P/Wild-2
Comet Tempel 1
Deep Impact Crash into Comet
Tempel 1
Deep Impact Tells a Tale of
the Comet
Comet Information
Hale-Bopp Fails Emission
Tests but Reveals Comet
Kuiper Belt Objects
Comets Beyond Neptune
Comet Tutorial
Make a Comet Nucleus
Comet Space Exploration
Comet Image/Animation
NASA's Hubble Space Telescope is
providing astronomers with extraordinary
views of comet 73P/SchwassmannWachmann 3, which is falling apart right
before our eyes. Recent Hubble images
have uncovered many more fragments
than have been reported by ground-based
observers. These observations provide an
unprecedented opportunity to study the
demise of a comet nucleus.
Amateur and professional astronomers
around the world have been tracking for
years the spectacular disintegration of
73P/Schwassmann-Wachmann 3. As it plunges toward a June 6th swing around
the Sun, the comet will pass Earth on May 12th, at a distance of 7.3 million miles,
or 30 times the distance between Earth and the Moon.
The comet is currently comprised
of a chain of over three dozen
separate fragments, named
alphabetically, stretching across
several degrees on the sky. (The
Sun and Moon each have an
apparent diameter of about 1/2 of a
degree.) Ground-based observers
have noted dramatic brightening
events associated with some of the
fragments (as shown in the bottom frame) indicating that they are
continuing to break-up and that some may disappear altogether.
Hubble caught two of the fragments, B and G, (top frames)
shortly after large outbursts in activity. Hubble also photographed fragment C (not shown), which was less
active. The resulting images reveal that a hierarchical destruction process is taking place, in which fragments are
continuing to break into smaller chunks. Several dozen "mini-fragments" are found trailing behind each main
fragment, probably associated with the ejection of house-sized chunks of surface material that can only be
detected in these very sensitive and high-resolution Hubble images.
1/23/2011 5:41 PM
Comet 73P/Schwassmann-Wachmann 3
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Sequential Hubble images of the B fragment, taken a few days apart, suggest that the chunks are pushed down
the tail by outgassing from the icy, sunward-facing surfaces of the chunks, much like space-walking astronauts
are propelled by their jetpacks. The smaller chunks have the lowest mass, and so are accelerated away from the
parent nucleus faster than the larger chunks. Some of the chunks seem to dissipate completely over the course of
several days.
Deep-freeze relics of the early solar system, cometary nuclei are porous and fragile mixes of dust and ices. They
can be broken apart by gravitational tidal forces when they pass near large bodies (for example, Comet
Shoemaker-Levy 9 was torn to pieces when it skirted near Jupiter in 1992, prior to plunging into Jupiter's
atmosphere two years later). They can also fly apart from rapid rotation of the nucleus, break apart because of
thermal stresses as they pass near the Sun, or explosively pop apart like corks from champagne bottles due to the
outburst of trapped volatile gases.
"Catastrophic breakups may be the ultimate fate of most comets," says planetary astronomer Hal Weaver of the
Johns Hopkins University Applied Physics Laboratory, who led the team that made the recent Hubble
observations and who used Hubble previously to study the fragmentations of comets Shoemaker-Levy 9 in
1993-1994, Hyakutake in 1996, and 1999 S4 (LINEAR) in 2000. Analysis of the new Hubble data, and data
taken by other observatories as the comet approaches the Earth and Sun, may reveal which of these breakup
mechanisms are contributing to the disintegration of 73P/Schwassmann-Wachmann 3.
German astronomers Arnold Schwassmann and Arno Arthur Wachmann discovered this comet during a
photographic search for asteroids in 1930, when the comet passed within 5.8 million miles of the Earth (only 24
times the Earth-Moon distance). The comet orbits the Sun every 5.4 years, but it was not seen again until 1979.
The comet was missed again in 1985 but has been observed every return since then.
During the fall of 1995, the comet had a huge outburst in activity and shortly afterwards four separate nuclei
were identified and labeled "A", "B", "C", and "D", with "C" being the largest and the presumed principal
remnant of the original nucleus. Only the C and B fragments were definitively observed during the next return,
possibly because of the poor geometry for the 2000-2001 apparition. The much better observing circumstances
during this year's return may be partly responsible for the detection of so many new fragments, but it is also
likely that the disintegration of the comet is now accelerating. Whether any of the many fragments will survive
the trip around the Sun remains to be seen.
Besides Weaver, the other members of the Hubble observing team are: Carey Lisse (JHU/APL), Philippe Lamy
(Laboratoire d'Astronomie Spatiale, France), Imre Toth (Hungarian Academy of Sciences), William Reach
(IPAC/Caltech), and Max Mutchler (STScI). Z. Levay (STScI)
Additional Image of Comet Borrelly
A Million Comet Pieces
This infrared image from NASA's Spitzer Space Telescope shows the broken
Comet 73P/Schwassman-Wachmann 3 skimming along a trail of debris left
during its multiple trips around the sun. The flame-like objects are the comet's
fragments and their tails, while the dusty comet trail is the line bridging the
Comet 73P /Schwassman-Wachmann 3 began to splinter apart in 1995 during
one of its voyages around the sweltering sun. Since then, the comet has
continued to disintegrate into dozens of fragments, at least 36 of which can be seen here. Astronomers believe
the icy comet cracked due the thermal stress from the sun.
The Spitzer image provides the best look yet at the trail of debris left in the comet's wake after its 1995 breakup.
1/23/2011 5:41 PM
Comet 73P/Schwassmann-Wachmann 3
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The observatory's infrared eyes were able to see the dusty comet bits and pieces, which are warmed by sunlight
and glow at infrared wavelengths. This comet debris ranges in size from pebbles to large boulders. When Earth
passes near this rocky trail every year, the comet rubble burns up in our atmosphere, lighting up the sky in
meteor showers. In 2022, Earth is expected to cross close to the comet's trail, producing a noticeable meteor
Astronomers are studying the Spitzer image for clues to the comet's composition and how it fell apart. Like
NASA's Deep Impact experiment, in which a probe smashed into comet Tempel 1, the cracked Comet
73P/Schwassman-Wachmann 3 provides a perfect laboratory for studying the pristine interior of a comet.
(Courtesy NASA/JPL-Caltech)
Hubble Provides Spectacular Detail of a Comet's Breakup
Hubble Space Telescope is providing astronomers with extraordinary views of
Comet 73P/Schwassmann-Wachmann 3. The fragile comet is rapidly disintegrating
as it approaches the Sun. Hubble images have uncovered many more fragments than
have been reported by ground-based observers. These observations provide an
unprecedented opportunity to study the demise of a comet nucleus. The comet is
currently a chain of over three dozen separate fragments, named alphabetically,
stretching across the sky by several times the angular diameter of the Moon. Hubble
caught two of the fragments (B and G) shortly after large outbursts in activity.
Hubble shows several dozen "mini-comets" trailing behind each main fragment,
probably associated with the ejection of house-sized chunks of surface material. Deep-freeze relics of the early
solar system, cometary nuclei are porous and fragile mixes of dust and ices that can break apart due to the
thermal, gravitational, and dynamical stresses of approaching the Sun. Whether any of the many fragments
survive the trip around the Sun remains to be seen in the weeks ahead. (Courtesy NASA, ESA, JHU/APL, STScI)
Comet 73P/Schwassmann-Wachmann 3 - Fragment B: Apr. 18, 2006
Hubble Space Telescope Advanced Camera for Surveys image of Comet
73P/Schwassmann-Wachmann 3 fragment B on April 18, 2006. (Courtesy NASA,
Comet 73P/Schwassmann-Wachmann 3 - Fragment B: Apr. 19, 2006
Hubble Space Telescope Advanced Camera for Surveys image of Comet
73P/Schwassmann-Wachmann 3 fragment B on April 19, 2006. (Courtesy NASA,
Comet 73P/Schwassmann-Wachmann 3 - Fragment B: Apr. 20, 2006
Hubble Space Telescope Advanced Camera for Surveys image of Comet
73P/Schwassmann-Wachmann 3 fragment B on April 20, 2006. (Courtesy NASA,
1/23/2011 5:41 PM
Comet 73P/Schwassmann-Wachmann 3
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Comet 73P/Schwassmann-Wachmann 3 - Fragments B, G
Ground-based color composite image of Comet 73P/Schwassmann-Wachmann
3 fragments B and G on April 21, 2006 made with a 8" f/1.5 Schmidt Camera.
(Courtesy M. J�ger and G. Rhemann)
Comet Introduction
Views of the Solar System copyright © 1995-2006 by Calvin J. Hamilton. All rights reserved. Privacy
1/23/2011 5:41 PM
Comet Shoemaker-Levy 9
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Table of Contents
Comet Shoemaker-Levy 9 (This Page)
Views of Shoemaker-Levy 9
Shoemaker-Levy 9 Impact
Shoemaker-Levy 9 Image Index
Hubble Press Release on the SL-9 Collision Results
Comet Tutorial
Links to other Comet Shoemaker-Levy Home Pages
Comet Shoemaker-Levy 9 Impact from JPL
Effelsberg Radio Observations of the Great Comet Crash
Comet Shoemake-Levy 9 page from SEDS
Comet Shoemaker-Levy 9 was the ninth short-periodic comet discovered by Eugene and Carolyn Shoemaker and David Levy. It was
first detected on a photograph taken on the night of March 24, 1993, with the 0.4-meter Schmidt telescope on Palomar Mountain in
California. The magnitude of the comet's brightness was reported as 14, more than a thousand times too faint to be seen with the
naked eye. The existence of this object was soon confirmed by James V. Scotti of the Spacewatch program at the University of
Through the observations and efforts of Brian G. Marsden and other astronomers, the comet's orbit was demonstrated to be around
Jupiter and that it had made a very close approach to Jupiter on July 7, 1992. During this close approach, the unequal Jupiter
gravitational attractions on the comet's near and far sides broke the fragile object apart. On March 27, an image was taken with the
2.2-m telescope on Mauna Kea in Hawaii that showed as many as 17 separate sub-nuclei strung out like pearls on a string 50 arc
seconds long. An early image taken by Scotti on March 30 is shown below.
Early Shoemaker/Levy 9 Image
On July 1, 1993 an image was taken with the Hubble Space Telescope (HST) that clearly shows at least 15 individual fragments in
one image frame of the train.
1/23/2011 5:44 PM
Comet Shoemaker-Levy 9
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Early HST Image
Since it was not at all obvious where the center of mass of this new comet lay, most observers were using the position of what
appeared to be the center of the train. This made an accurate orbit (or orbits) difficult to determine; however, after numerous
observations of the comet, astronmers determined that the comet had passed within 96,000 kilometers (60,000 miles) of the center of
Jupiter or 25,000 kilometers (16,000 miles) from the cloud tops during the July 8, 1992, approach. They also determined that it would
again pass within 25,000 kilometers (16,000 miles) of the center of Jupiter, on July 19, 1994. This distance was less than the radius of
Jupiter. In other words, the comet, or at least parts of it, could very well hit Jupiter.
Shoemaker-Levy 9 had been in a rapidly changing orbit around Jupiter for some time before this, probably for at least several
decades. It did not fragment during earlier approaches to Jupiter because these were made at much greater distances than the 1992
approach. The comet's previous approaches to Jupiter probably came no closer than 9 million kilometers (5.6 million miles).
By December 9 1993, the probability of impact for all the large fragments of Shoemaker-Levy 9 was calculated to be greater than
99.99%. The fragments would hit over a period of several days, centered on July 19, on the night side of Jupiter. Unfortunately, this
was the back side of Jupiter as viewed from Earth. The impact site would be close to the limb of Jupiter, near 75° from the midnight
meridian and only a few degrees beyond the dark limb as seen from Earth.
The disruption of a comet into multiple fragments is an unusual event, the capture of a comet into an orbit about Jupiter is even more
unusual, and the collision of a large comet with a planet is an extraordinary, millennial event.
Views of Shoemaker-Levy 9
HST 1993 Mosaic
This high resolution image is a mosaic of images taken by the Hubble Telescope on January 24-27, 1994.
Twenty nuclei are visible with one slightly outside of the field-of-view (to the right). Each nucleus has its own
coma and tail. The fourth nucleus from the left (the first bright one) is apparently starting to separate into at
least two pieces. (Courtesy NASA/JPL)
HST Images
These images were taken with the Hubble telescope's new camera's on January 24-27, 1994. In the upper
image, 20 nuclei are visible with one slightly outside of the field-of-view (to the right). Each nucleus has its own
coma and tail. The fourth nucleus from the left (the first bright one) is apparently starting to separate into at
least two pieces. The width and height of this image project to distances of 605,000 kilometers (376,000 miles)
and 126,500 kilometers (78,600 miles), respectively, at the comet.
The lower left and right parts of the screen show the region near the brightest nucleus at higher resolution. To the left is the new
image from the corrected camera, while the image to the right shows old data from the aberrated camera. (Courtesy NASA/JPL)
Depictions of the Shoemaker-Levy 9 Collision
In this series of depictions, comet Shoemaker-Levy 9 impacting Jupiter is shown from three different
perspectives: at left, from the viewpoint of Earth; center, from the Voyager 2 spacecraft in the outer reaches
of the solar system; and, at right, from Jupiter's south pole. For visual appeal, most of the large cometary
fragments are shown close to one another in this image. At the time of Jupiter impact, the fragments will be
separated from one another by several times the distances shown. (Courtesy NASA/JPL)
Additional Shoemaker-Levy 9 Depictions
Viewpoint from the Earth.
Viewpoint from Voyager 2.
Viewpoint from Juipter's South Pole.
Halley's Comet
Shoemaker-Levy 9 Impact
1/23/2011 5:44 PM
Shoemaker-Levy 9 / Jupiter Impact
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Table of Contents
Table of Fragment Impacts and Times
Views of Shoemaker-Levy 9 / Jupiter Impact
Fragments of comet P/Shoemaker-Levy 9 collided with Jupiter on July 16-22, 1994. The
results were spectacular. At least 20 large fragments impacted the planet at 60 kilometers
(37 miles) per second, causing plumes thousands of kilometers high. They left hot bubbles
of gas in the atmosphere and great dark scars which lasted for months after the collision.
The largest fragments were estimated at 2 kilometers (1.2 miles) in diameter.
The fragments impacted Jupiter at approximately 45° south latitude and 6.5° longitude from
the limb, and 15° from the dawn terminator just out of view of the Earth. Eleven minutes
after impact, the point in the atmosphere where the impact occurred would rotate across the
limb and 14 minutes later would cross the dawn terminator. The fragments were moving at
an angle of 83° from the Jovian north to south axis and struck the cloud tops at about 45°.
The following table lists the impact times as seen from the Earth, calculated by Don
Yeomans and Paul Chodes.
Table of Fragment Impacts and Times.
Impact Time
Impact Time
& 1-sigma error
20:11:00 (3 min)
02:50:00 (6 min)
07:12:00 (4 min)
11:54:00 (3 min)
15:11:00 (3 min)
00:33:00 (5 min)
07:32:00 (2 min)
19:31:59 (1 min)
Missing since 12/93
10:21:00 (4 min)
22:16:48 (1 min)
Missing since 7/93
10:31:00 (4 min)
15:23:00 (7 min)
Missing since 3/94
19:44:00 (6 min)
1/23/2011 5:44 PM
Shoemaker-Levy 9 / Jupiter Impact
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20:12:00 (4 min)
05:33:00 (3 min)
15:15:00 (5 min)
18:10:00 (7 min)
21:55:00 (7 min)
04:22:00 (5 min)
08:05:30 (3 min)
Views of Shoemaker-Levy 9 / Jupiter Impact
Galileo Image of Impact W
These four images of Jupiter and the luminous night-side impact of fragment W of Comet Shoemaker-Levy 9
were taken by the Galileo spacecraft on July 22, 1994. The spacecraft was 238 million kilometers (148 million
miles) from Jupiter at the time, and 621 million kilometers (386 million miles) from Earth. The spacecraft was
about 40 degrees from Earth's line of sight to Jupiter, permitting this direct view. The first image, taken at an equivalent time to 8:06:10
Greenwich Mean Time (1:06 a.m. Pacific Daylight Time), shows no impact. In the next three images, a point of light appears, brightens
so much as to saturate its picture element, and then fades again, seven seconds after the first picture. The location is approximately
44 degrees south as predicted; dark spots to the right are from previous impacts. Jupiter is approximately 60 picture elements in
diameter. (Courtesy NASA)
Impact of H-fragment observed at La Silla
This image was obtained with the TIMMI instrument at the European Southern Observatory's 3.6-meter
telescope on July 18, 1994, 20:11 UT. It shows the rising plume above the impact site of fragment H of comet
Shoemaker-Levy 9. The image was made in the 9.1 - 10.4 micron band in the far-infrared region. The surface
brightness of this plume was about 50 times that of the Jupiter disk. The temperature was measured as more
than 300 K. (Courtesy European Southern Observatory)
HST UV Image of Impacts H, Q1, R, D, G, L, B, N & Q2
This ultraviolet image shows Jupiter's atmosphere at a wavelength of 2550 Angstroms after many impacts by
fragments of comet Shoemaker-Levy 9. The most recent impactor is fragment R which is below the center of
Jupiter (third dark spot from the right). This photo was taken by the Hubble Space Telescope at 3:55 EDT on
July 21, about 2.5 hours after R's impact. A large dark patch from the impact of fragment H is visible rising on
the morning (left) side. Proceeding to the right, other dark spots were caused by impacts of fragments Q1, R, D
and G (now one large spot), and L, with L covering the largest area of any seen thus far. Small dark spots from
B, N, and Q2 are visible with careful inspection of the image. The spots are very dark in the ultraviolet because
a large quantity of dust is being deposited high in Jupiter's stratosphere, and the dust absorbs sunlight. (Courtesy Hubble Space
Telescope Comet Team)
HST Image of Impacts E/F, H, N, Q1, Q2, R and D/G
Image of Jupiter with the Hubble Space Telescope Planetary Camera. Eight impact sites are visible. From left to
right are the E/F complex (barely visible on the edge of the planet), the star-shaped H site, the impact sites for
tiny N, Q1, small Q2, and R, and on the far right limb the D/G complex. The D/G complex also shows extended
haze at the edge of the planet. The features are rapidly evolving on time scales of days. The smallest features
in this image are less than 200 kilometers (124 miles) across. (Courtesy Hubble Space Telescope Comet Team)
HST Image of Impacts D and G
This image of Jupiter shows the impact sites of fragments "D" and "G" from Comet Shoemaker-Levy 9. The
large feature was created by the impact of fragment "G" on July 18, 1994 at 3:28 a.m. EDT. It entered Jupiter's
atmosphere from the south at a 45-degree angle, and the resulting ejecta appears to have been thrown back
along that direction. The smaller feature to the left of the fragment "G" impact site was created on July 17, 1994,
at 7:45 a.m. EDT by the impact of fragment "D". The "G" impact has concentric rings around it, with a central
dark spot 2,500 kilometers (1,550 miles) in diameter. This dark spot is surrounded by a thin dark ring 7,500 kilometers (4,661 miles) in
diameter. The dark thick outermost ring's inner edge has a diameter of 12,000 kilometers (7,460 miles) - about the size of the Earth.
(Courtesy Hubble Space Telescope Comet Team)
HST Views of Comet Fragment G Impact Zone
This image shows two views of the impact zone on Jupiter of fragment G of Comet Shoemaker-Levy 9. The
image on the left was made in green light. The image on the right is the same field taken through a methane
filter. These images were obtained by the Hubble Space Telescope in the early morning of July 18, 1994. The
impact site is visible as a complex pattern of circles seen in the lower left of the partial planet image. The small
dark feature to the left of the pattern of circles is the impact site of fragment D. The dark, sharp ring at the site
of the fragment G impact is 80% of the size of the Earth. (Courtesy Dr. Heidi Hammel, Massachusetts Institute
of Technology/NASA HST)
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HST G Plume Image
These images taken by the Hubble Telescope show the G impact site through methane, red, green, blue and
violet filters. (Courtesy Hubble Space Telescope Comet Team)
HST A, C and E Impact Sites
This Hubble image of Jupiter was obtained with a filter at 336 nm (near-ultraviolet light) at 18:42 UT on 17 July
1994. Three impact sites (from left to right: C, A, and E) are visible as dark spots across the lower portion of the
image. All other features in this picture are characteristic of Jupiter's normal state. The feature created by the
impact of A is 23 hours old in this image. The C and E features are 12 and 5 hours old, respectively. Io is seen
on the left as a dark spot in the northern hemisphere, and the Great Red Spot is visible on the right limb.
(Courtesy Hubble Space Telescope Jupiter Imaging Team)
Evolution of the G Impact Site
This mosaic of Hubble images shows the evolution of the G impact site on Jupiter. The images from lower right
to upper left show: the impact plume at 07/18/94 07:38 UT (about 5 minutes after the impact); the fresh impact
site at 07/18/94 at 09:19 UT (1.5 hours after impact); the impact site after evolution by the winds of Jupiter (left),
along with the L impact (right), taken on 07/21/94 at 06:22 UT (3 days after the G impact and 1.3 days after the
L impact); and further evolution of the G and L sites due to winds and an additional impact (S) in the G vicinity,
taken on 07/23/94 at 08:08 UT (5 days after the G impact). (Credit: R. Evans, J. Trauger, H. Hammel and the
HST Comet Science Team and NASA)
IRTF Infrared Image of Q & R Impacts
This is a 2.07 micron image of Jupiter taken on the NASA Infrared Telescope Facility, Mauna Kea, Hawaii, at
08:54 on July 21, 1994. Io, the closest of the jovian moons, can be seen crossing the planet in the northwest of
the image (top right). The Great Red Spot is visible in the south east of the planet. At the collision latitudes, the
impact due to Fragment Q is just setting on the west. Just to the east of it, the R Fragment impact site shows
up very brightly. Another four impact sites form a chain of spots behind R. (Courtesy NASA IRTF Comet
Science Team)
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Kuiper Belt Objects
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Hubble Observations Shed New Light on Jupiter Collision
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Was it a comet or an asteroid? Scientists are debating that question as they continue to
pore over Hubble Space Telescope imaging and spectroscopic data gleaned in the wake of
the spectacular July 1994 bombardment of Jupiter by comet P/Shoemaker-Levy 9. Their
initial findings, combined with results from other space-borne and ground-based telescopes,
shed new light on Jupiter's atmospheric winds, its immense magnetic field, the mysterious
dark debris from the impacts, and the composition of the doomed comet itself.
The Last Days Of The Comet
Before the comet impact, there was a great deal of speculation and prediction about
whether the 21 nuclei would survive before reaching Jupiter, or were so fragile that
gravitational forces would pull them apart into thousands of smaller fragments. Hubble
helped answer this question by watching the nuclei until about 10 hours before impact.
HST's high resolution images show that the nuclei, the largest of which were probably a few
kilometers across, did not break up catastrophically before plunging into Jupiter's
atmosphere. This reinforces the notion that the atmospheric explosions were produced by
solid, massive impacting bodies. HST's resolution also showed that the nuclei were
releasing dust all along the path toward Jupiter, as would be expected from a comet. This
was evident in the persistence of spherical clouds of dust surrounding each nucleus
throughout most of the comet's journey. About a week before impact, these dust clouds
were stretched out along the path of the comet's motion by Jupiter's increasingly strong
Was P/Shoemaker-Levy 9 A Comet Or An Asteroid?
At present, observations seem to slightly favor a cometary origin, though an asteroidal origin
cannot yet be ruled out. The answer isn't easy because comets and asteroids have so much
in common: they are small bodies; they are primordial, having formed 4.6 billion years ago
along with the planets and their satellites; either type of object can be expected to be found
in Jupiter's vicinity. The key difference is that comets are largely icy while the asteroids are
virtually devoid of ice because they formed too close to the Sun.
What Is That Dark Stuff Made Of?
The HST Faint Object Spectrograph (FOS) detected many gaseous absorptions associated with the impact sites and followed their
evolution over the next month. Most surprising were the strong signatures from sulfur-bearing compounds like diatomic sulfur (S2),
carbon disulfide (CS2), and hydrogen sulfide (H2S). Ammonia (NH3) absorption also was detected. The S2 absorptions seemed to
fade on timescales of a few days, while the NH3 absorptions at first got stronger with time, and finally started fading after about one
month. During observations near the limb of Jupiter, the FOS detected emissions from silicon, magnesium and iron that could only
have originated from the impacting bodies, since Jupiter itself normally does not have detectable amounts of these elements.
Swept Across Jupiter
Observations made with HST's Wide Field Planetary Camera-2, a week and a month after impact, have been used to make global
maps of Jupiter for tracking changes in the dark debris caught up in the high-speed winds at Jupiter's cloudtops. This debris is a
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Hubble Observations Shed New Light on Jupiter Collision
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natural tracer of wind patterns and allows astronomers a better understanding of the physics of the Jovian atmosphere. The high
speed easterly and westerly jets have turned the dark "blobs" originally at the impact sites into striking "curly-cue" features. Although
individual impact sites were still visible a month later despite the shearing, the fading of Jupiter's scars has been substantial and it
now appears that Jupiter will not suffer any permanent changes from the explosions.
Hubble's ultraviolet observations show the motion of very fine impact debris particles now suspended high in Jupiter's atmosphere.
The debris eventually will diffuse down to lower altitudes. This provides the first information ever obtained about Jupiter's high altitude
wind patterns. Hubble gives astronomers a "three dimensional" perspective showing the wind patterns at high altitudes and how they
differ from those at the visible cloudtop level. At lower altitudes, the impact debris follows east-west winds driven by sunlight and
Jupiter's own internal heat. By contrast, winds in the high Jovian stratosphere move primarily from the poles toward the equator
because they are driven mainly by auroral heating from high energy particles.
Piercing Jupiter's Magnetic Field
About four days before impact, at a distance of 2.3 million miles from Jupiter, nucleus "G" of comet P/Shoemaker-Levy 9 apparently
penetrated Jupiter's powerful magnetic field, the magnetosphere. (Jupiter's magnetosphere is so vast, if visible from Earth, it would be
about the size of the full Moon.)
Hubble's Faint Object Spectrograph (FOS) recorded dramatic changes at the magnetosphere crossing that provided a rare
opportunity to gather more clues on the comet's true composition. During a two-minute period on July 14, HST detected strong
emissions from ionized magnesium (Mg II), an important component of both comet dust and asteroids. However, if the nuclei were
ice-laden - as expected of a comet nucleus - astronomers expected to detect the hydroxyl radical (OH). Hubble did not see OH,
casting some doubt on the cometary nature of comet P/Shoemaker-Levy 9. Eighteen minutes after comet P/Shoemaker- Levy 9
displayed the flare-up in Mg II emissions, there was also a dramatic change in the light reflected from the dust particles in the comet.
New Auroral Activity
HST detected unusual auroral activity in Jupiter's northern hemisphere just after the impact of the comet's "K" fragment. This impact
completely disrupted the radiation belts which have been stable over the last 20 years of radio observations.
Aurorae, glowing gases that create the northern and southern lights, are common on Jupiter because energetic charged particles
needed to excite the gases are always trapped in Jupiter's magnetosphere. However, this new feature seen by Hubble was unusual
because it was temporarily as bright or brighter than the normal aurora, short-lived, and outside the area where Jovian aurorae are
normally found. Astronomers believe the K impact created an electromagnetic disturbance that traveled along magnetic field lines into
the radiation belts. This scattered charged particles, which normally exist in the radiation belts, into Jupiter's upper atmosphere.
X-ray images taken with the ROSAT satellite further bolster the link to the K impact. They reveal unexpectedly bright X-ray emissions
that were brightest near the time of the K impact, and then faded.
The Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, Inc. (AURA) for
NASA, under contract with the Goddard Space Flight Center, Greenbelt, Md. The Hubble Space Telescope is a project of international
cooperation between NASA and the European Space Agency (ESA).
Donald Savage
Headquarters, Washington, D.C.
September 29, 1994
(Phone: 202/358-1547)
Jim Elliott
Goddard Space Flight Center, Greenbelt, Md.
(Phone: 301/286-6256)
Ray Villard
Space Telescope Science Institute, Baltimore, Md.
(Phone: 410/338-4514)
Comet Shoemaker-Levy 9
Views of the Solar System Copyright © 1997-2009 by Calvin J. Hamilton. All rights reserved. Privacy Statement.
1/23/2011 5:45 PM
109P/Swift-Tuttle - Wikipedia, the free encyclopedia
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From Wikipedia, the free encyclopedia
Comet Swift-Tuttle (formally designated as 109P/Swift-Tuttle)
is a comet that was independently discovered by Lewis Swift on
July 16, 1862 and by Horace Parnell Tuttle on July 19, 1862.
The comet made a return appearance in 1992, when it was
rediscovered by Japanese astronomer Tsuruhiko Kiuchi and
became visible with binoculars.[1] Its solid nucleus is about 27
kilometers (16.8 miles) across, considerably larger than the
10 km object hypothesized to have wiped out the dinosaurs in
the Cretaceous–Paleogene extinction event.[2]
It is the parent body of the Perseid meteor shower, perhaps the
best known shower and among the most reliable in performance.
An unusual aspect of its orbit is that it is presently captured into
a 1:11 orbital resonance with Jupiter; it completes one orbit for
every 11 of Jupiter.[4]
Discovered by:
Lewis Swift
Horace Parnell Tuttle
Discovery date:
July 16, 1862
1737 N1; 1737 II; 1862
1862 III; 1992 S2; 1992
Orbital characteristics A
October 10, 1995 (JD
Aphelion distance: 51.225 AU
Perihelion distance: 0.9595 AU
Semi-major axis:
26.092 AU
Orbital period:
133.28 a
Last perihelion:
December 11, 1992
Next perihelion:
July 12, 2126
The comet is on an orbit which puts it close to the Earth and the
Moon.[5] Upon its 1992 rediscovery, the comet's date of
perihelion passage was off from the then-current prediction by 17 days. It was then noticed that, if its next
perihelion passage (August 14, 2126) was also off by another 15 days, the comet would very likely strike the
Earth or Moon. Given the size of the nucleus of Swift-Tuttle, this was of some concern. This prompted amateur
astronomer and writer Gary W. Kronk to search for previous apparitions of this comet. He found the comet was
most likely observed by the Chinese in 69 BC and AD 188, which was quickly confirmed by Brian G.
Marsden.[6] This information and subsequent observations have led to recalculation of its orbit, which indicates
the comet's orbit is very stable, and that there is absolutely no threat over the next two thousand years.[7]
Astronomers believe that in the 2126 pass it will likely be a great naked-eye comet like Hale-Bopp.[1]
A close encounter with Earth is predicted for the comet's return to the inner solar system in the year 4479,
around Sept. 15; the closest approach is estimated to be 0.03-0.05 AU, with a probability of impact of
1 × 10−6.[4] Subsequent to 4479, the orbital evolution of the comet is more difficult to predict; the probability of
Earth impact per orbit is estimated as 2 × 10−8.[4] As the largest Solar System object that makes repeated close
passes of Earth, and which does so at a relative velocity of 60 km/s,[2][8] leading to an estimated impact energy
of ~27 times that of the K-T impactor,[9] Comet Swift-Tuttle has been described as "the single most dangerous
object known to humanity".[8]
1. ^ a b Britt, Robert (2005-08-11). "Top 10 Perseid Meteor Shower Facts" (
/050811_perseid_facts.html) . Retrieved
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G A R Y W. K R O N K ' S C O M E T O G R A P H Y
Past, Present, and Future Orbits by Kazuo Kinoshita
Copyright © 1992 by Herman Mikuz (Crni Vrh Observatory, Slovenia)
This image was obtained on 1992 December 15, with 3.5/250mm lens, CCD, and narrow-band H2O+ filter, centered at
620nm (FWHM=10nm). The field of view is 2.9x1.9 degrees. (The webmaster has inverted the image to better
represent the appearance of the comet.)
Lewis Swift (Marathon, New York, USA) discovered this comet in Camelopardalis on 1862 July 16, while examining the
northern sky with his 11.4-cm Fitz refractor. He described the comet as a somewhat bright telescopic object, but did not
report it since he thought he was observing the comet Schmidt had found on July 2. Without knowledge of Swift's
observation, Horace Parnell Tuttle (Harvard College Observatory, Cambridge, Massachusetts, USA) independently
discovered this comet on July 19.19 and noted it was heading northward. He then made an official announcement. When
Swift heard of Tuttle's find, he immediately realized the comet seen on July 16 was not Schmidt's and made his
announcement to get credit for his first comet discovery.
There were several independent discoveries. Thomas Simons (Dudley Observatory, Albany, New York, USA)
independently discovered the comet on July 19.30. He remarked, "When first seen it appeared as a nebula considerably
condensed at the centre, the light being intense enough to be easily observed when the wires of the micrometer were
illuminated." Antonio Pacinotti and Carlo Toussaint (Florence, Italy) found the comet on July 22. Schjellerup (Copenhagen)
found this comet in Camelopardalis on the night of July 26/27. He described it as a bright nebulosity with a very slow
movement. On July 27.98, Schjellerup and d'Arrest confirmed the discovery with a large refractor. Schjellerup remarked,
"The comet is rather bright, the nucleus equalled a star of 7th magnitude." He added that at a magnification of 226x they
saw a distinct extension in the direction of the sun, while the surrounding nebulosity was 3 arc minutes across. On
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September 1, John Tebbutt (Windsor, New South Wales) independently discovered this comet, not yet having received a
notification of its prior discovery. With a 3.25-inch telescope, he noted the comet's nucleus was badly defined and did not
admit accurate determinations of position.
J. F. Julius Schmidt (Athens, Greece) made numerous observations of the comet from 1862 August to September. He
examined his magnitude estimates of the comet's nucleus and determined that, on the average, maximum light occurred
every 2.691±0.269 days, while minimum light occurred every 2.711±0.284 days.
The earliest orbits were computed at the end of July and in early August. These were parabolic orbits indicating a
perihelion date of 1862 August 22 to 24. During the next few years several astronomers computed elliptical orbits indicating
an orbital period between 120 and 125 years, with the first attempt at a definitive orbit coming in 1889 when F. Hayn
determined the orbital period as 119.64 years. During 1971, B. G. Marsden and Zdenek Sekanina took 212 positions
obtained during the period of 1862 July 22 to October 22, applied perturbations by all nine planets, and determined the
orbital period as 119.98 years. A couple of years later, Marsden looked at the possibility of trying to link Swift-Tuttle to an
earlier comet. He found two in the 18th century that looked promising--1737 (Kegler) and 1750 (Wargentin). The 1750
comet appeared at just about the right time expected for Swift-Tuttle if that comet's motion was integrated back from 1862.
The problem, however, was that it was moving too fast. The 1737 comet actually exhibited a motion consistent for what
would have been expected for Swift-Tuttle if the perihelion date had fallen on June 15 of that year; however, as Marsden
pointed out, the main point this identity "is that the comet's osculating period would have to have been some 10 yr longer
than is indicated by the observations in 1862." Marsden made two predictions for a forthcoming return. First, using the
definitive orbit of Sekanina and himself, he suggested a perihelion date of 1981 September 16.93. Second, he suggested that
if the link to the comet of 1737 was valid, the comet would likely return to perihelion on 1992 November 25.85.
Minor searches for the comet began in 1980, which was within the error range given by calculations, and more rigorous
searches were conducted in 1981 and 1982, but nothing was found.
Tsuruhiko Kiuchi (Japan) discovered a comet on 1992 September 26.76 and reported it to the National Astronomical
Observatory (Tokyo). He said it was magnitude 11.5. H. Kosai of that observatory subsequently reported it to the (Central
Bureau for Astronomical Telegrams) and suggested it might be comet Swift-Tuttle. Several observers were able to confirm
the comet within the next 24 hours and the indicated direction and rate of motion was consistent with what would be
expected for Swift-Tuttle. Brian G. Marsden (Central Bureau) was not able to do a precise linkage between the 1862 and
1992 positions, but he did provide an orbit that adequately represented all available positions. It indicated a perihelion date
of 1992 December 12.29, a perihelion distance of 0.959 AU, and an orbital period of 135.29 years.
Observations made within the first days following the recovery revealed the comet's actual magnitude was near 9 and that
the coma diameter was about 4 arc minutes.The comet steadily brightened during the following weeks. It surpassed
magnitude 8.5 shortly after October began and had climbed to 6.0 by the beginning of November. A faint tail over a degree
long was already visible on photographs after mid-October and this continued to brighten during the following weeks. By
mid-November it was possible to see over 2 degrees of tail with binoculars. Along other lines of observation, astronomers
reported that observations during the first half of November were revealing the production rates of various gases, of which
OH, Methanol, CS, and water were among the first identified.
The comet surpassed magnitude 5.0 right at mid-November and continued brightening. The ion tail was 6.7 degrees long
on November 23 when Herman Mikuz (Slovenia) imaged it with 10-minute exposure CCD frames. Most interesting was a
report by L. Jorda and J. Lecacheux (Paris-Meudon) and F. Colas (Observatoire de Paris) that observations of a nuclear jet
with the 1.05-m telescope and CCD camera at Pic du Midi over the period of November 20-26 indicated a probable nuclear
rotation period of 2.9 days. Compare this to the periodicity earlier noted by Schmidt in the brightness of the nucleus back in
1862. As November came to a close brightness estimates were still at 5.0 and the comet showed no sign of fading until just
before mid-December.
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Copyright © 1992 by Gerald Rhemann
This image was obtained on 1992 November 24.74 UT with the
171/200/257mm Schmidt camera. Exposure time was 10
minutes and the photographic emulsion was Kodak
Ektachrome 100. The comet's total magnitude was then about
5.0. (The image has been cropped by the webmaster to save
By early December of 1992 it was becoming obvious that independent orbital calculations by Marsden and Donald K.
Yeomans which attempted to fit the 1862 and 1992 observations were becoming increasing further off the mark in
predicting the motion of this comet. Marsden attempted a nongravitational solution and managed the best fit of the available
positions, but noted large discrepancies in the positions of 1862 October. Interestingly, this new orbit allowed two
prediscovery images to be located. The first was found by R. Haver (Cima Ekar) on a plate exposed with a 0.4-m f/2.5
Schmidt on 1992 January 3.08. The comet was described as stellar with a magnitude of 17.5. The second was found by L.
Kohoutek (Calar Alto) on a plate exposed on January 7.09 with a 0.8-m Schmidt. He estimated the magnitude as 18. Around
this time, Gary Kronk (Troy, Illinois, USA) announced the liklihood that comets reported by the Chinese in -68 and +188
were good candidates for Swift-Tuttle. Independent computations by Marsden and G. Waddington (Oxford University)
confirmed the links and noted a purely gravitational solution worked better to fit the apparitions. In addition, it was realized
that no favorable apparitions would have occurred following 188 until 1737.
The comet was last seen on 1995 March 29.48, by observers at Siding Spring Observatory (Australia).
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