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Transcript
Objective – Describe the characteristics of comets, asteroids, and meteors.
Comet Facts, Myths, and Legends
(from NASA - Space Science: Adventure Is Waiting/Hubble – Amazing Space)
The word "comet" comes from the Greek word for "hair."
Our ancestors thought comets were stars with what looked
like flowing hair trailing behind.
For centuries, scientists thought comets traveled in the
Earth's atmosphere. In 1577, observations by Danish
astronomer Tycho Brahe showed that they actually traveled
far beyond the moon.
Sir Isaac Newton (1642-1727), the great English scientist,
discovered that comets move in elliptical (egg-shaped)
orbits around the Sun. He also thought that comets were
members of the Solar System, just like planets, and that
they could return over and over again. He was right!
As early as the 1700's, scientists began developing
mathematical formulas that could predict the orbit of
a particular comet around the Sun. At that time,
calculators and computers didn’t exist, so everyone
had to do the calculations by hand!
Most astronomers in the 1500's and early 1600's
thought that a comet came once and was never seen again. They believed that a comet
approached the Sun in a straight line, spun around it, and then disappeared into space
in a straight path.
~1~
Objective – Describe the characteristics of comets, asteroids, and meteors.
People did not always know what comets were. In ancient
times, people thought comets were "power rays" of
supernatural beings. They thought comets contained fire
because they were so bright in the sky.
Some people in ancient times thought that a comet was a curse.
To save himself from the "curse of the comet," Emperor Nero of
Rome had all possible successors to his throne executed.
In 1910, people panicked when a comet passed through
Earth’s path around the Sun. In Chicago, people sealed their
windows to protect themselves from the comet’s poisonous
tail. Others committed suicide. Special "Comet Protecting
Umbrellas," gas masks, and "anti-comet pills" were sold.
Not everyone saw comets as bad luck. Some thought they
brought good luck. They also believed that comets carried
angels through the heavens.
People have known about comets, unlike other small
bodies in the Solar System, since ancient times. The
Chinese recorded visits by Halley's Comet as far back as
240 B.C.
~2~
Objective – Describe the characteristics of comets, asteroids, and meteors.
The famous Bayeux Tapestry, which commemorates the
Norman Conquest of England in 1066, depicts an image of
Halley's Comet bright in the sky before the Battle of
Hastings.
Some people thought this meant that King Harold would lose
his throne to William, the Duke of Normandy. He did!
Edmund Halley of England studied comets and developed a
theory suggesting that those sighted in 1531, 1607 and 1682
were actually the same object. He was the first to predict
successfully the comet’s next appearance in 1758, but he
died 16 years before the comet returned.
Halley’s Comet reappears every 76
years. Its next appearance is in 2061.
Maybe you will see it return!
Comets leave a trail of debris behind them. If their path crosses
Earth's path, then at that point, every year for a long time, there
will be meteor showers as the long-gone comet's debris strikes our
atmosphere.
Some of these meteor showers occur every year when the Earth
passes the place where the comet had been long ago.
~3~
Objective – Describe the characteristics of comets, asteroids, and meteors.
The Perseid meteor shower occurs every year between
August 9 and 13 when the Earth passes through the orbit of
the Swift-Tuttle comet. Halley's Comet is the source of the
Orionid shower in October.
Comets are brightest when they are near the Sun.
Comet Hale-Bopp 1995
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.
Comet Swift-Tuttle 1982
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
~4~
Objective – Describe the characteristics of comets, asteroids, and meteors.
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 System.
Comet Hyakutake 1996
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 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 1985
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 15km (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,
~5~
Objective – Describe the characteristics of comets, asteroids, and meteors.
is called the Orionids meteor shower. Comet Halley will return to the inner Solar
System in the year 2061.
Comet Shoemaker-Levy 9 1993
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.
(source: hubblesite.org)
~6~
Objective – Describe the characteristics of comets, asteroids, and meteors.
Myths vs. Reality - Comets
(from NASA: Amazing Space)
Myth
Comets come from regions outside the Solar System.
Reality
Comets are part of the Solar System. Scientists believe they come from one of two
locations within the Solar System: the Kuiper belt and the Oort cloud. The comets that
we see often – every 100 years – come from the Kuiper belt, and comets that we see
rarely – every few thousand years – come from the Oort cloud.
Myth
Comets are composed of the same material as asteroids.
Reality
Although comets and asteroids are both tiny bodies that orbit in the Solar System,
their composition is different. Asteroids are mostly rock with some ice, while comets
are mostly ice with some rock.
Myth
Comets always have tails.
Reality
Comets do not always have tails. They develop a fuzzy, shell-like cloud called a coma,
and one, two, or three tails when near the Sun. Comets have no coma or tail when far
away from the Sun.
~7~
Objective – Describe the characteristics of comets, asteroids, and meteors.
Myth
All comets look the same and don't change their appearance.
Reality
Comets have a coma and one, two, or three tails when near the Sun, and no coma or
tail when far away from the Sun. (A coma is a cloud of gaseous material surrounding
the nucleus.)
Myth
Pluto is the most distant and last object in the Solar System.
Reality
Beyond Pluto's orbit is a group of icy objects known as the Kuiper Belt, from which
short- period comets emerge. Farther still is a sphere of icy bodies, called the Oort
Cloud, from which long-period comets emerge. Short-period comets visit the inner
Solar System frequently, while the long-period comets visit infrequently.
Myth
There is empty space between the planets.
Reality
There is gas and dust, also known as the interplanetary medium, between the planets.
Comets are responsible for depositing some of the gas and dust found in the inner
Solar System.
~8~
Objective – Describe the characteristics of comets, asteroids, and meteors.
Name _____________________________________________________________
Comet Facts, Myths, and Legends Worksheet
1. The word comet comes from a Greek word meaning…
a. beard.
b. hair.
c. mane.
d. ponytail.
2. Who was the scientist who proved that comets traveled far beyond the Moon?
a. Tycho Brahe
b. Galileo
c. Edmund Halley
d. Sir Isaac Newton
3. From ancient times, people knew what comets were.
a. True
b. False
4. To save himself from the comet’s curse, Emperor Nero did what?
a. Left Rome for his safety.
b. Killed all his possible successors.
c. Sent his sons to convents.
d. Did nothing because he didn’t believe in comet curses.
5. In 1910, people bought which of the following item(s) to protect themselves from
Comet Halley?
a. Comet protecting umbrellas
b. Anti-comet pills.
c. Gas mask
d. All of the above
6. Some people thought comets brought good luck because they carried angels across
the heavens.
a. True
b. False
7. When did the Chinese first record visits by Comet Halley?
a. 440 B.C.
b. 240 B.C.
c. 240 A.D.
d. 440 A.D.
~9~
Objective – Describe the characteristics of comets, asteroids, and meteors.
8. The Bayeux Tapestry showed Comet Halley in the sky during the Battle of Hastings
in 1066 A.D. People thought this meant King ___________ would lose the throne.
a. Charles
b. George
c. Harold
d. Richard
9. Edmund Halley proposed a hypothesis that the comets seen in 1531, 1607, and 1682
were the same comets. He predicted the comet would return again in 1758. Edmund
Halley was…
a. correct.
b. incorrect.
Match the Comet with the year it will return.
_____ 10. Comet Hale-Bopp
A. Never
_____ 11. Comet Halley
B. 2061
_____ 12. Comet Hyakutake
C. 2102
_____ 13. Comet Shoemaker-Levy 9
D. 4395
_____ 14. Comet Swift-Tuttle
E. 15,669
Match the term with its definition.
_____ 15. Coma
_____ 16. Comet
A. A “dirty snowball” consisting of ices, rocks, and
dirt.
_____ 17. Dust tail
B. A stream of charged particles ejected from the
surface of the Sun.
_____ 18. Nucleus
C. Forms when the solar wind separates dust from the
coma, pushing it outward away from the Sun.
_____ 19. Solar wind
D. The cloud of gas and dust that forms around a
comet's nucleus.
E. The solid icy/rocky part of a comet.
~10~
Objective – Describe the characteristics of comets, asteroids, and meteors.
Identify which statement is “reality” or a “myth.”
_____ 20. Comets come from regions outside the Solar System.
A. Myth
_____ 21. Asteroids are mostly rock; comets are mostly ice with
some rock.
B. Reality
_____ 22. Comets do not always have a tail.
_____ 23. All comets look the same and don't change their
appearance.
_____ 24. Comets are found beyond the orbit of Pluto.
_____ 25. There is empty space between the planets.
Statement
26. Only a professional astronomer with a powerful
telescope can discover a new comet.
27. About 100 years ago, some people bought cometprotecting umbrellas and anti-comet pills to protect
themselves.
28. The closer a comet is to the Sun, the brighter it will
appear.
29. The ancients thought comets were the power rays of
supernatural beings.
30. A meteor shower occurs when many comets at once
pass over the Earth.
True
False
A
B
A
B
A
B
A
B
A
B
Scoring Guide
95-100% - 4 75-84% - 2.5 45-54% - 1
90-94% - 3.5 65-74% - 2 1-44% - .5
85-89% - 3 55-64% - 1.5
~11~
Objective – Describe the characteristics of comets, asteroids, and meteors.
Comet Facts, Myths, and Legends – Key I
1. The work comet comes from a Greek word meaning…
b. hair
2. Who was the scientist who proved that comets traveled far beyond the Moon?
a. Tycho Brahe
3. From ancient times, people knew what comets were.
b. False
4. To save himself from the comet’s curse, Emperor Nero did what?
c. Killed all his possible successors.
5. In 1910, people bought which of the following item(s) to protect themselves from
Comet Halley?
d. All of the above
6. Some people thought comets brought good luck because they carried angels across
the heavens.
a. True
7. When did the Chinese first record visits by Comet Halley?
b. 240 B.C.
8. The Bayeux Tapestry showed Comet Halley in the sky during the Battle of Hastings
in 1066 A.D. People thought this meant King ___________ would lose the throne.
c. Harold
~12~
Objective – Describe the characteristics of comets, asteroids, and meteors.
9. Edmund Halley proposed a hypothesis that the comets seen in 1531, 1607, and 1682
were the same comets. He predicted the comet would return again in 1758. Edmund
Halley was…
a. correct.
D 10. Comet Hale-Bopp
B 11. Comet Halley
E 12. Comet Hyakutake
A 13. Comet Shoemaker-Levy 9
C 14. Comet Swift-Tuttle
D 15. Coma
A 16. Comet
C 17. Dust tail
E 18. Nucleus
B 19. Solar wind
A 20. Comets come from regions outside the Solar System.
B 21. Asteroids are mostly rock; comets are mostly ice with some rock.
A 22. Comets do not always have a tail.
A 23. All comets look the same and don't change their appearance.
B 24. Comets are found beyond the orbit of Pluto.
A 25. There is empty space between the planets.
~13~
Objective – Describe the characteristics of comets, asteroids, and meteors.
B 26. Only a professional astronomer with a powerful telescope can discover a new
comet.
A 27. About 100 years ago, some people bought comet-protecting umbrellas and anticomet pills to protect themselves.
A 28. The closer a comet is to the Sun, the brighter it will appear.
A 29. The ancients thought comets were the power rays of supernatural beings.
B 30. A meteor shower occurs when many comets at once pass over the Earth.
~14~
Objective – Describe the characteristics of comets, asteroids, and meteors.
Comet Facts, Myths, and Legends – Key II
1. b
2. a
3. b (2 choices)
4. c
5. d
6. a (2 choices)
7. b
8. c
9. a (2 choices)
16. A (5 choices)
17. C (5 choices)
18. E (5 choices)
19. B (5 choices)
20. A (2 choices)
21. B (2 choices)
22. A (2 choices)
23. A (2 choices)
24. B (2 choices)
25. A (2 choices)
26. B (2 choices)
27. A (2 choices)
28. A (2 choices)
29. S (2 choices)
30. B (2 choices)
~15~
Objective – Describe the characteristics of comets, asteroids, and meteors.
Comet Facts, Myths, and Legends
Scoring Guide
29-30 – 4
27-28 – 3.5
26 – 3
23-25 – 2.5
20-22 – 2
17-19 – 1.5
14-16 – 1
1-13 – .5
0–0
95-100% - 4
90-94% - 3.5
85-89% - 3
75-84% - 2.5
65-74% - 2
55-64% - 1.5
45-54% - 1
1-44% - .5
~16~