NAME: ___________________________________ GRADE & SECTION: __________________ DATE: _________ SCORE: _____

SCIENCE 8 – UNIT 2 Module 3 (COMETS, METEORS AND ASTEROIDS) Handout

COMETS
 The word “comet” comes from the Greek word aster kometes, which NOTE: Meteorites are of importance to scientists in studying the
means “long-haired star” occurrence of different elements and compounds on Earth. There are
 Also known as “Dirty Snow Ball”; are loose collections of ice, dust, three types of meteorites: stony, stony-iron, and iron meteorites.
and small rocky particles; orbits are usually very long, narrow ellipses METEOR SHOWER
 Move in a highly elliptical shaped Meteoroid can come from comets. Comets orbit the Sun and leave
Structure of a Comet: fragments on their orbit as they continue their journey around the Sun. These
1. A Comet’s Head fragments continue to orbit the Sun just like their parent comets. When Earth
- Nucleus – the central solid mass of a comet. It is made up of about orbits the Sun and passes through the orbit where comet fragments are found,
85% water ice, with frozen carbon dioxide, carbon monoxide, we observe many streaks of light from Earth which is called meteor shower.
methane, ammonia, dirt and dust mixed in with an average size from Some Important Meteor Shower Calendar:
1km to 20 km in diameter  Quarantids: Peak date – January 3
- Coma – outer layer (water vapor, CO2, and other gases) can reach  Perseids: Peak date – August 12- the most popular meteor shower
a diameter of 200,000 km, larger than the size of Jupiter. as seen from the Northern Hemisphere
- Hydrogen Cloud – even larger and more tenuous cloud that  Orionids: Peak date – October 21
surrounds the coma, made of light hydrogen gas
 Leonids: Peak date – November 17 – are best known for producing
2. A Comet’s Tail
great meteor storms in the years of 1833, 1866, 1966, and 2001
- As a comet approaches the sun and heats up, some of its gas and
dust stream outward, forming a tail  Geminids: Peak date – December 13
- Most comets have 2 tails: gas tail (ion tail) and dust tail SUMMARY: Comets, Asteroids and Meteors
- Tails point away from the sun because of the force of the solar wind These three celestial bodies are remnants of the formation of the
solar system, which have irregular shapes and sizes with rocky composition.
Both comets and asteroids reflect light from the sun at varying amounts
depending on the size and composition. Their major difference is their origin;
comets usually come from the Oort Cloud and few from the Kuiper Belt.
Asteroids originate from the main Asteroid Belt. Meteors come from fragments of
comets. Meteor showers are caused by Earth passing through the debris path of
a comet. Comet and asteroid both orbit the sun and move relatively slow unlike
the meteors which move faster when viewed from Earth.
When a comet or asteroid enters and passes through Earth’s
atmosphere, it will be changed physically and chemically. Usually, the fragments
from space are completely burnt and only cosmic dust reach Earth. But when
these fragments do survive passing through Earth’s atmosphere, the fragments
can be as small as a sand grain or as big as a boulder. The impact releases
great amounts of energy that can damage hundreds of miles from the point of
impact. In fact, the discovery of an impact crater at the Yucatan peninsula in
Mexico is being touted by scientists as the strongest evidence to support the
Impact Theory which explains the extinction of dinosaurs and other species of
Most comets are found in 2 regions of the solar system: animals in plants 65 million years ago.
1. Kuiper Belt- doughnut-shaped region that extends beyond Neptune’s POSTEST: Answer the following.
I. ASTRONOMY WORDS: Asteroid, Comet, Meteors, Meteorite, Oort Cloud,
orbit to about 100 times Earth’s distance from the sun where short-
Meteoroid, Nucleus, Kuiper Belt, Fireballs
period comets are found A. Fill in the following items with words from the list above.
2. Oort Cloud – spherical region of comets that surround the solar 1. ______________are the flashes of light caused by friction when particles from
system out to more than 1,000 times the distance between Pluto and space enter the atmosphere as “shooting stars”
the sun where long-period comets are found 2-3. ______________ the ______________ seem to be the reservoirs of comets
Two Groups of comets: 4. The ________________ of a comet is essentially the entire comet when it is
 Short-period Comets – have orbits that take less than 200 years far from the sun
5. Meteors that become unusually bright are called ______________________
 Long-period Comets – have orbits that take more than 200 years
B. Pick three words from the list above that were not used in item 1 to 5. Write
one complete sentence for each of these words.
ASTEROIDS
 Asteroids are solid pieces of rock that have been left around the Solar II. Identification: Identify what is being asked in the following statements.
System from the time when the planets formed. They are also called ___________1. Unusually bright and big meteors
“Minor Planets” or “Planetoids” ___________2. Remains of meteoroids that reach Earth’s surface
 Most asteroids are found in the asteroid belt located between the ___________3. Icy planetisimals formed in the outer regions of the solar system
___________4. An area around the sun beyond the orbit of Neptune that is that
orbits of Mars and Jupiter
is believed to be one of the reservoirs of comets
 Smaller than a planet but larger than a meteoroid ___________5. Small bodies orbiting the sun believed to be remnants from the
 Asteroids are quite irregular in shape and therefore the light they early days of the solar system and mostly found between the
reflect from the Sun fluctuates as they move and rotate orbit of Mars and Jupiter
 Orbit the Sun in slightly elliptical orbits III. Multiple Choice. Encircle the letter of your answer.
1. Which of the following is NOT an asteroid impact?
 Are made of metals, silicate, iron, nickel, and carbon
a. Living things may die or go extinct
Groups of Asteroids Classified by Orbits: b. Tectonic plate motion may be disturbed
1. Apollo Asteroids – Asteroids that cross Earth’s orbit c. Debris sent into the atmosphere may leave the planet in darkness
2. Amor Asteroids – Asteroids that cross Mars’ orbit, but not Earth’s d. Temperature of atmosphere may drop to near freezing point for years
3. Trojan Asteroids – Asteroids found within the orbit of Jupiter 2. The solar system is composed of the sun, planets, and other members. The
4. Asteroid Belt - Asteroids found in the area between Mars and Jupiter three minor members of the solar system are ____________.
where most asteroids are found a. Asteroid, meteors, Biyo c. Biyo, Pluto, comets, meteors
3 Types of Asteroid Compositions: b. Pluto, asteroids, meteoroids d. asteroids, meteoroids, comets
1. C-Type Asteroids – Asteroids made of carbonaceous materials, 3. Which of the following happens during a meteor shower?
a. There is a couple getting married
typical of the outer asteroid belt and the Trojan asteroids
b. Earth passes through an asteroid belt
2. S-Type Asteroids – Asteroids made of stony or silicate materials, c. The head of a comet hits Earth’s atmosphere
typical of the inner asteroid belt d. Earth passes through a swarm of dust particles in space
3. M-Type Asteroids – Asteroids made mostly of metals 4. Which of the following is a good description of a meteorite?
Some Famous Asteroids: a. Rock particles from space that strike the ground
 CERES (1000 km in diameter) – the largest asteroid. First asteroid b. Rock particles from space that pass through Earth’s atmosphere
discovered in 1801. It is a C-Type found in the main belt c. A streak of light caused by the impact of rock particles from space
with our atmosphere d. All of the above
 DACTYL (1.4 km in diameter) – It is the first asteroid moon found. It
5. Which of the following is the cause of a comet tail?
orbits the asteroid named Ida a. Interplanetary material streaming into the comet
 EROS (a cigar-shaped asteroid) – First asteroid found to travel b. Dust collected by the comet as it moves in its orbit
mainly inside the orbit of Mars and the first to be orbited and landed c. Melting and evaporation of ice from the comet’s core
on by a spacecraft. It is named for the god of love in Greek mythology d. Solar wind blowing more gases from the central core
6. Most of the asteroids orbit the sun in a belt between orbits of ____________
 IDA – the second asteroid to be observed close up by a spacecraft
a. Mars and Earth c. Venus and Earth
found to have a moon that orbits it. The moon was named Dactyl b. Mars and Jupiter d. Jupiter and Saturn
 PSYCHE (256 km in diameter) – Discovered in 1852. An M-Type 7. Meteorite & comets are important in studying the origin of solar system. Why?
found in the main belt. If its metal could be mined, it would supply all a. Both have recently been found
our metal needs for hundreds, perhaps thousands of years b. They represent the material which formed planets
 VESTA (555 km in diameter) – Discovered in 1807. It is an S-Type c. They have dust tails that are ten million kilometers long
d. They are fragment of planets that have been recently produced
found in the main belt. It is the brightest asteroid and can
8. Which of the following is the correct description of an asteroid?
occasionally be seen with the unaided eye. Its stony composition is a. A planetoid c. an icy material in space
largely basalt – a volcanic type of rock b. A satellite of a planet d. a planet in other star systems
9. Your friend asks you about the streak of light that was observed in the sky and
METEORS, METEOROIDS, and METEORITES seemed to have fallen on Earth’s surface. What will you tell your friend?
 METEOROID: A small rocky object in space that come from comets a. It is a comet c. It is a meteorite
or asteroids. Sizes may range from dust-sized to 1 km b. It is a meteor d. It is a star that fell from heaven
 METEOR: A meteoroid that enters Earth’s atmosphere and burns up. 10. Why is a comet compared to dirty snowball?
a. It is surrounded by a smog d. It is made up of soil and rocks
They are usually 80-160 km high in the atmosphere
b. It appears to be brown when observed in space
 METEORITE: The rock that makes it to the Earth’s surface after c. It is made up of frozen gases and small particles of rocky and metallic
surviving the journey through the Earth’s atmosphere materials