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.
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.
1
Objective – Describe the characteristics of comets, asteroids, and meteors.
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, when Halley’s Comet returned,
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.
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 successfully
predict the comet’s next appearance in 1758, but he died 16
years before the comet returned.
2
Objective – Describe the characteristics of comets, asteroids, and meteors.
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.
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 SwiftTuttle 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.
3
Objective – Describe the characteristics of comets, asteroids, and meteors.
NASA knows of no asteroid or comet currently on a
collision course with Earth. The probability of such
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.
Comet Hale-Bopp
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 HaleBopp 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 1992
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
4
Objective – Describe the characteristics of comets, asteroids, and meteors.
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
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
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.
5
Objective – Describe the characteristics of comets, asteroids, and meteors.
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 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.
Myths vs. Fact - Comets
Myth
Comets come from regions outside the Solar System.
Fact
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.
Fact
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.
6
Objective – Describe the characteristics of comets, asteroids, and meteors.
Myth
Comets always have tails.
Fact
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.
Myth
All comets look the same and don't change their appearance.
Fact
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.
Fact
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.
Fact
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.
7
Objective – Describe the characteristics of comets, asteroids, and meteors.
Name _______________________________________________ Score _______/21
Comet Facts, Myths, and Legends
1. The word for comet comes from the Greek word for…
a. beard.
b. fleece.
c. hair.
d. moustache.
2. Who was the first astronomer to show comets travel beyond the Moon?
a. Sir Isaac Newton
b. Tycho Brahe
c. Edmund Halley
d. Johannes Kepler
3. At one time, astronomers believed comets came once and were never seen again.
a. True
b. False
4. When Halley’s Comet returned in 1910, people sold…
a. comet protecting umbrellas.
b. anti-comet pills.
c. gas masks.
d. all of the above.
5. The Chinese recorded a visit from Halley’s Comet as far back as _________ B.C.
(Enter a number)
6. The Bayeux (bye-you) Tapestry shows Halley’s Comet. Some people thought their
king would lose his throne. Who was that King?
a. King William
b. King Phillip
c. King Henry
d. King Harold
7. Halley’s Comet returns every ______ years. (Enter a number)
8. When the Earth travels through a trail of debris left by a comet, this occurs.
a. Asteroid shower
b. Meteor shower
c. Meteorite shower
d. Rain shower
8
Objective – Describe the characteristics of comets, asteroids, and meteors.
9. When the Earth passes through the debris left by Comet Swift-Tuttle, we see this
meteor shower.
a. Aquarids
b. Leonids
c. Orionids
d. Perseids
10. There is no possibility that a comet struck Earth and was responsible for killing the
dinosaurs.
a. True
b. False
11. The comet that may have struck the Earth was the size of which mountain?
a. Mount Everest
b. Mount McKinley
c. Mount Olympus
d. Mount Rainer
Match the famous comet with the year it appeared, last appeared, or will return.
_____ 12. Comet Hale-Bopp
A. 1992
_____ 13. Comet Halley
B. 1995
_____ 14. Comet Hyakutake
C. 1996
_____ 15. Comet Shoemaker Levy 9
D. Will return again in 2061
_____ 16. Comet Swift-Tuttle
E. This come struck Jupiter in 1994.
Identify whether the statement is fact or myth.
_____ 17. Comets come from outside of the Solar System.
A. Fact
_____ 18. Comets are composed of the same material as asteroids.
B. Myth
_____ 19. Comets do not always have tails.
_____ 20. Comets do not change their appearance.
_____ 21. Pluto is the most distant object in our Solar System.
9
Objective – Describe the characteristics of comets, asteroids, and meteors.
Comet Facts, Myths, and Legends – Key
1. The word for comet comes from the Greek word for…
c. hair
2. Who was the first astronomer to show comets travel beyond the Moon?
b. Tycho Brahe
3. At one time, astronomers believed comets came once and were never seen again.
a. True
4. When Halley’s Comet returned in 1910, people sold…
d. all of the above
5. The Chinese recorded a visit from Halley’s Comet as far back as…
240
6. The Bayeux (bye-you) Tapestry shows Halley’s Comet. Some people thought their king would
lose his throne. Who was that King?
d. King Harold
7. Halley’s Comet returns every ______ years.
76
8. When the Earth travels through a trail of debris left by a comet, this occurs.
b. Meteor shower
9. When the Earth passes through the debris left by Comet Swift-Tuttle, we see this meteor
shower.
d. Perseids
10
Objective – Describe the characteristics of comets, asteroids, and meteors.
10. There is no possibility that a comet struck Earth and was responsible for killing the dinosaurs.
b. False
11. The comet that may have struck the Earth was the size of which mountain?
a. Mount Everest
B 12. Comet Hale-Bopp (5 choices)
D 13. Comet Halley (5 choices)
C 14. Comet Hyakutake (5 choices)
E 15. Comet Shoemaker Levy 9 (5 choices)
A 16. Comet Swift-Tuttle (5 choices)
B 17. Comets come from outside of the Solar System. (5 choices)
B 18. Comets are composed of the same material as asteroids. (5 choices)
A 19. Comets do not always have tails. (5 choices)
B 20. Comets do not change their appearance. (5 choices)
A 21. Pluto is not the most distant object in our Solar System. (5 choices)
11
Objective – Describe the characteristics of comets, asteroids, and meteors.
Comet Facts, Myths, and Legends
1. c
2. b
3. a (2 choices)
4. d
5. 240
6. d
7. 76
8. b
9. d
10. b (2 choices)
11. a
12. B (5 choices)
13. D (5 choices)
14. C (5 choices)
15. E (5 choices)
16. A (5 choices)
17. B (2 choices)
18. B (2 choices)
19. A (2 choices)
20. B (2 choices)
21. A (2 choices)
Scoring Guide
19-21 – 3
17-18 – 2.5
15-16 – 2
13-14 – 1.5
11-12 – 1
1-10 – .5
0–0
12