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Asteroids and
Comets and
Meteors, Oh My!
(source Astronomy Picture of the Day)
(source NASA Galileo)
(source lxixixl)
After completing this workbook, students should
be able to do the following:
Standard/
Description (Pinnacle)
Pinnacle
7.18.2
Use precise scientific language in oral and
written communication.
3.5.2
Describe the characteristics of comets,
asteroids, and meteors.
Falling Stars
The sight of a falling star is exciting. Before you can say, “Look!” the streak is gone. You
point to where it was and ask others if they saw it, too. Often, no one else sees the
speedy flight of light flash by. You’re left trying to describe what you saw and felt. You
stare at the dark space, hoping another will streak across the sky.
What is a falling star? A falling star is not a star at all. It is not even a piece of a star.
Stars are huge balls of burning gas sending off great amounts of energy in the form of
light and heat. Stars are much bigger than our planet. Stars do not fall; they stay in
their own places in their own galaxies. Our Sun is a star.
A falling star is a meteor. Meteors are streaks of light in the sky that we can see when
a small speck of dust burns up high in the air above us. Where do these specks of dust
come from? Comets! (And, don’t forget space dirt!)
Astronomers call this dirt and comet dust “meteoroids.” Meteoroids are different sizes.
Some are larger. Most are tiny. Meteoroids hit the Earth’s atmosphere at super, high
speed. Sometimes it’s faster than 90,000 miles per hour. When they are in the
atmosphere, they become “meteors.” The meteor usually burns up. This creates the
streak of light we see. It looks like a star falling from the sky. This is why they are
called a “falling star.” Meteors usually last just a second or two.
pg. 1 Sometimes, there are meteor showers. It’s exciting to watch a meteor shower. You
usually see four or five meteors in an hour. During a meteor shower, you might see more
than 80 meteors in an hour. Scientists also watch these meteors. They record the
numbers, the brightness, and the paths of the meteors.
Why do we have meteor showers? They happen when the Earth passes through the tail
of a comet. Like the dust cloud surrounding Pigpen in the “Peanuts” comics, a meteoroid
stream travels along with the comet on its orbit through the Solar System.
Some people are confused by comets and meteors. A comet is different from a meteor.
A comet is usually larger and travels slowly across the night sky. A very bright comet
only appears once or twice in a century but it remains in the sky for many days or
months. Comets appear to be bright balls with fat tails. They do not fall rapidly in the
sky; you would have to watch one for hours or days to see its movement. The center of a
comet is a ball of frozen gas, dust, and water. Like planets or moons, comets orbit
around the Sun.
The comet that causes the Leonids is called Tempel-Tuttle. It is named after two
scientists who discovered it at the end of 1865.The scientists were not working
together; one was in France and one was in America. They were each looking through
telescopes. Both astronomers spotted the comet and reported their finding. The comet
they found was not a big, bright comet. It is so small that it can only be seen with a
telescope. The comet Tempel-Tuttle is about 2 1/2 miles in diameter.
When comets get close to the Sun, they begin to warm up and their icy material begins
to melt. Tiny grains of dirt that have been riding on the comet for perhaps four and a
half billion years fly off into space to join a long stream of orbiting meteoroids.
When the Earth hits this stream of comet junk from Tempel-Tuttle, meteors seem to
shoot out of the constellation Leo. That’s why this meteor shower is called the Leonids.
The Leonids are famous. The reason that the Leonids are so famous is that sometimes
they cause a meteor storm! In a meteor storm, over 1,000 meteors blaze across the sky
every hour. In 1833, people all over America woke up to see hundreds of stars falling
every minute! All night, the sky was brightened by meteors that rocketed through the
night by the thousands! Since no telescopes or fancy equipment were needed to see the
storm, ordinary people were able to see that wonderful and rare sight. Many artists
tried to paint pictures of the “rain of stars “that fell so heavily that night. Newspapers
ran many stories about the storm. What they saw was a Leonids meteor storm. This
display was so beautiful and amazing that meteors suddenly captured the attention and
pg. 2 imagination of people everywhere. Scientists were inspired to begin a serious study of
meteors and their causes.
The best way to watch a meteor storm is with your eyes. Telescopes are not required.
Dress warmly. Set up a comfortable lounge chair with blankets and snacks or spread out
a blanket. Lie down and look up at the sky. Watch the beautiful flashes of light from
tiny “sky candles “created in the long, ago dawn of our Solar System.
Directions
Some of the following words and phrases describe comets. Some words and phrases
describe meteors. Some words and phrases describe meteoroids. Some describe more
than one. Based on what you learned in the article “Falling Stars,” write “comets,”
“meteors,” and/or “meteoroids” by the appropriate words and phrases.
 Shooting stars _________________________________________________
 Composed of minerals and ice ______________________________________
 Orbits Sun ____________________________________________________
 Has a tail _____________________________________________________
 Speedy streak of light ___________________________________________
 Usually the size of a grain of sand ___________________________________
 Hits the atmosphere faster than 90,000 miles per hour ___________________
 Surface melts into gas and dust when gets close to Sun ___________________
 Visible for a second or two ________________________________________
 Travels slowly across the night sky __________________________________
 May come in showers or storms _____________________________________
 Remains in the sky for many days or weeks _____________________________
pg. 3 Asteroids, Comets, Meteor0ids
(an activity from spaceday.org)
What is considered a small body?
Any object in the sky that is smaller than a planet or a moon, such as an asteroid,
a comet, or a meteoroid
Materials
 Ruler
 Tape
 Scissors
Safety Concerns: Scissors. Use scissors in the
appropriate manner.
Procedure
1. Get a plain sheet of white paper and turn it sideways.
2. Measure four equal strips of paper, each 2,inches
wide.
3. Cut strips (see diagram).
4. Select one of the paper strips; draw “tick mark” on the strip at ¼,inch. Draw a line
across the strip. Cut off the ¼,inch section; this represents the scaled size of a
meteoroid; tape the strip to the Data Sheet in the space provided.
Cut here!
¼-inch strip
pg. 4 5. Starting at the end of strip where the cut was made, repeat the process, but this
time measure ¾,inch; again, draw a line at ¾,inch and cut off the ¾,inch section; this
section represents the scaled size of a comet; tape it to the Data Sheet, too.
Cut here!
¾-inch strip
6. Tape all the strips together. Measure a strip that is 40,inches in length. These strips
represent the scaled size of an asteroid.
7. Tape the strip to the bottom of the Data Sheet in the space provided; neatly fold
remaining strips back and forth over the bottom strip.
Data Sheet
pg. 5 Making Comparisons
1. Based on your scale model, which two small bodies are most similar in size?
__________________________________________________________________
__________________________________________________________________
pg. 6 It was on a dark and starry night of New Year’s Day, 1801. Giuseppe Piazzi, an Italian
monk, was at work in his observatory on Sicily. He
was a member of the Celestial Police. This was a group
of astronomers looking for a missing planet between
Jupiter and Mars. That night
he was confirming and
cataloging stars in Taurus.
While checking other
astronomers’ work, he saw a
tiny point of light. He thought
it was just a dim star no one had cataloged. He checked for it
the next night, but it had moved! He watched it move on
January 3 and 4. What he was observing was not a star! He
wrote to Johan Bode and told him what he had found; Bode was
certain he had found “the missing planet.”
And the Plot Thickens . . .
Cloudy weather set in. Piazzi was so sick that he could not observe the skies on some
January nights. By January 24, he realized what he had discovered. He wrote a friend:
“I have announced the star as a comet. But the fact that the star is not
accompanied by any nebulosity [clouds of dust and gas] and that its movement is
very slow and rather uniform has caused me many times to seriously consider that
perhaps it might be something better than a comet. I would be very careful,
however, about making this conjecture [this idea] public.”
He wrote to Bode the next day. He did not receive the letter until March 20. When the
letter reached Bode, he studied his star maps. He convinced Piazzi that he had found
pg. 7 the “missing planet.” Piazzi named the object Ceres. Piazzi’s friend, Baron von Zach
announced the discovery in his Monthly Correspondence summer of 1801.
To establish that he really had found a new planet, Piazzi needed to be able to predict
his new planet’s orbit (or path) in the sky. This was necessary so that other astronomers
could find the object when they wished to investigate it more thoroughly. Piazzi had
observed Ceres for six weeks, but he did not have enough information to calculate
the object’s orbit by any mathematical methods available at that time. After that,
William Herschel and others searched unsuccessfully for the object, and several
astronomers attempted to work out Ceres’ orbit from Piazzi’s limited data, but they
each came up with different results. Ceres appeared to be lost. It had passed into the
evening’s twilight before anyone else could verify Piazzi’s observations.
Piazzi tried to predict Ceres’ orbit. Astronomers need this information so they
could try to find it. He observed Ceres for six weeks. He did not have enough
information to determine Ceres’ orbit. After that, others searched for Ceres in vain.
Several astronomers tried to work out Ceres’ orbit from his data. They each came up
with different results. Ceres appeared to be lost. No one could verify Piazzi’s
observations.
But Carl Friedrich Gauss, a young German mathematician, came to the rescue! In
October 1801, he applied his new method of “determining the path of a celestial
body” to Ceres’ orbit. With surprising speed and accuracy, Gauss used Piazzi’s
observations to predict where the new “planet” should be found. Imagine Gauss’s
excitement when Baron von Zach found Ceres on the night of December 7, just where
Gauss said it would be!
Actually, von Zach found four stars at that location, but when the
weather cleared again on December 18, one of the stars was gone.
Von Zach finally confirmed that he had recovered the missing
object (Ceres) on January 1, 1802, exactly one year after
Piazzi’s first sighting. Using Gauss’ results, Wilhelm Olbers, an
amateur astronomer in Bremen, also found Ceres with his telescope.
Piazzi received a letter sent by the secretary of state on behalf of the king of Sicily
commending him on the discovery of Ceres. Instead of giving Piazzi a medal, the king
agreed to buy the Palermo Observatory a new telescope.
pg. 8 Von Zach had two roles in this exciting event. First, he found the missing Ceres.
Second, his publication, Monthly Correspondence, provided
information about Ceres.
By 1809, Gauss had refined the mathematical procedure he
used to determine Ceres’ orbit, and it became the standard
procedure for orbital calculations.
The “missing planet” was found, lost, and found again. All’s well that ends well…except
this was not the end! This was only the beginning! Many more asteroids had yet to be
discovered. The NASA Dawn mission will travel to Ceres but first will study another
asteroid named Vesta.
Questions and Analysis (Hint: Look at bold/italics in the reading for
answers.)
Early Asteroids Discoveries
1. When and where did Giuseppe Piazzi live and work?
__________________________________________________________________
2. What was Piazzi doing when he saw a new point of light?
__________________________________________________________________
3. What was different about the point of light that he discovered on New Year’s Night,
1801?
__________________________________________________________________
4. Johan Bode was certain that Piazzi had discovered…
__________________________________________________________________
The most exciting phrase to hear in science, the one that heralds
new discoveries, is not 'Eureka!' (I have discovered it!) but
'That's funny...'
,Isaac Asimov
pg. 9 And the Plot Thickens…
5. Piazzi announced the star was a comet, but he changed his mind. Why?
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
6. Baron von Zach announced the discovery of Ceres in his publication. What was the
publication’s name?
__________________________________________________________________
7. Piazzi couldn’t find Ceres again over a six, week period. Why did he couldn’t he find
Ceres?
__________________________________________________________________
__________________________________________________________________
8. How much time passed between Ceres’ first discovery and its rediscovery?
__________________________________________________________________
9. Baron von Zach played two important roles in the rediscovery of Ceres. What were
they?
a. ___________________________________________________________
__________________________________________________________________
b. ___________________________________________________________
__________________________________________________________________
pg. 10 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.
pg. 11 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
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!
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 "anticomet 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.
pg. 12 Share two legends about comets.
a. ___________________________________________________________
__________________________________________________________________
__________________________________________________________________
b. ___________________________________________________________
__________________________________________________________________
__________________________________________________________________
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.
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! Here’s a good picture of the
comet.
pg. 13 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.
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.
Did comets kill the dinosaurs? Sixty-five million years
ago, 70 percent of all species then living on Earth
disappeared within a very short time. This included
the last of the great dinosaurs. One possibility is that
a comet about 10 kilometers in size struck the Earth.
Scientists think that the impact disrupted the
environment by displacing great amounts of dirt and
rocks into the air.
The explosion that this object must have caused was similar
to the explosion a rock the size of Mount Everest, traveling
10 times faster than the fastest bullet, would cause if it hit
the Earth. There is a 65,million,year,old crater from an
impact of similar magnitude just off the coast of Mexico in
the Yucatan Peninsula.
NASA knows of no asteroid or comet currently on a collision course with Earth. The
chance of a collision is quite small. In fact, as far as we can tell, no large object is likely
to strike Earth any time in the next several hundred years.
pg. 14 Explain how comets may have been responsible for the dinosaurs becoming extinct.
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
Based on your reading of “Comet Facts, Myths, and Legends,” would you say the
following statements are true or false?
Statement
1.
It's possible that a big comet striking the Earth killed off
the dinosaurs.
2.
Only a professional astronomer with a powerful telescope can
discover a new comet.
3.
About 100 years ago, some people bought comet-protecting
umbrellas and anti-comet pills to protect themselves.
4,
The closer a comet is to the Sun, the brighter it will appear.
5.
The ancients thought comets were the power rays of
supernatural beings.
6.
A meteor shower occurs when many comets at once pass over
the Earth.
True
False
Comet Hale-Bopp
On July 23, 1995, 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 brightness was due to its large size. While the
nuclei of most comets are about 1 to 2 miles across, Hale-Bopp's
was estimated to be 25 miles across. It was visible even through
pg. 15 bright city skies. It may have been the most viewed comet in 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
This comet was first seen in July 1862 by American
astronomers Lewis Swift and Horace Tuttle. Comet SwiftTuttle appears every 120 years. It leaves behind a trail
of dust that Earth passes through in August. As Earth
passes through the dust, we can see the Perseid meteor
shower. Comet Swift-Tuttle could one day collide with
Earth because the two orbits closely intercept each
Earth. The latest calculations show that it will pass 15 million miles from Earth on its
next trip to the inner Solar System.
Comet Hyakutake
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 bright comet
with a nucleus of 1 to 2 miles flew-by Earth. It had one
of the longest tails ever observed. The Hubble Space
Telescope studied this comet in great detail. This is not
Comet Hyakutake's first visit to the inner Solar System. It is believed that it was here
about 8,000 years ago. Its orbit will not return for about 14,000 years.
Comet Halley
Comet Halley is 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
pg. 16 approaches the Sun, its 9,mile nucleus sheds ice and rock into space. This debris forms
an orbiting trail. When falling to Earth, it is called the Orionids meteor shower. Comet
Halley will return to the in 2061.
Comet Shoemaker-Levy 9
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 as the comet's pieces crashed into Jupiter. 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.
Short-period comets (orbital periods of less than 200 years) tend to come from
the Kuiper Belt—a region beyond the orbit of Neptune similar in shape to the asteroid
belt. Long-period comets (orbital periods of more than 200 years) tend to come
from the Oort Cloud. Based on the reading, complete the table below. s
Comet
How Long It Takes to
Orbit Sun (Years)
Where It Came From
Comet Hale-Bopp
Comet Swift-Tuttle
Comet Hyakutake
Comet Halley
pg. 17 Myths vs. Reality , Comets
Myth
Comets come from regions outside the Solar System.
Reality
Comets are part of the Solar System. Scientists believe they come from either the
Kuiper belt or the Oort cloud. The comets that we see every 100 years (or less) come
from the Kuiper belt. Comets that we see 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 structure is different. Asteroids are mostly rock with some ice. Comets are
mostly ice with some rock.
Myth
Comets always have tails.
Reality
Comets do not always have tails. They develop a fuzzy
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.
Myth
All comets look the same and don't change their appearance.
pg. 18 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. Short-period
comets come from there. Farther still is a sphere of icy bodies, called the Oort Cloud,
Long-period comets come from there. Short-period comets visit the inner Solar System
regularly. Long-period comets visit once in a while.
Myth
There is empty space between the planets.
Reality
There is gas and dust between the planets. Comets are responsible for depositing some
of the gas and dust found in the inner Solar System.
Identifying Comets
1. List two facts about comets.
a. ___________________________________________________________
__________________________________________________________________
pg. 19 b. ___________________________________________________________
__________________________________________________________________
2. List a myth about comets.
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
pg. 20 Asteroid, Comet, or Meteor?
Place an “X” in the appropriate boxes to indicate characteristics of asteroids, comets,
and meteors.
Asteroid
Comet
Meteor
Made of ice,
dust, and gas.
Appears as a
streak in the sky.
Made of rock
and/or metal.
Orbits the
Sun.
Often called
“shooting stars.”
Sometimes called
a “dirty
snowball.”
Orbits between
Mars and
Jupiter.
Most are found in
the Oort Cloud or
Kuiper Belt.
pg. 21