Transcript Comets

Chapter 16 Section 5
Comets, Asteroids, and
Meteors
Ch16 S5 Essential Questions
1. What are the characteristics of
comets?
2. Where are most asteroids found?
3. What are meteoroids and how do
they form?
Comets
• Farther our in space, near the
edge of the solar system a huge
cloud formed.
• This cloud is believed by some
astronomers to be the home of
comets.
Minor Members of the Solar System
Comets
 A comet orbits the sun. A comet is made up of
ice, dust, and small rocky particles. You can
think of a comet as a “dirty snowball.”
 Comets are small bodies made of rocky and
metallic pieces held together by frozen gases.
Comets generally revolve about the sun in
elongated orbits.
 Comets are loose collections of ice, dust,
and small rocky particles whose orbits are
usually very long, narrow ellipses.
Minor Members of the Solar System
Comets
 Coma
• The brightest part of a comet is the head. A comet’s head is
made up of a nucleus and a coma. The nucleus is the solid
core of a comet. The coma is a fuzzy outer layer made up
of clouds of gas and dust.
• A small glowing nucleus with a diameter of only a few
kilometers can sometimes be detected within a coma. As
comets approach the sun, some, but not all, develop a
tail that extends for millions of kilometers.
Minor Members of the Solar System
Comets
 Kuiper Belt
• Like the asteroids in the inner solar system, most Kuiper
belt comets move in nearly circular orbits that lie roughly in
the same plane as the planets.
 Oort Cloud
• Comets with long orbital periods appear to be distributed in
all directions from the sun, forming a spherical shell around
the solar system called the Oort cloud.
Minor Members of the Solar System
Comets
 Halley’s Comet
• The most famous short-period comet is Halley’s
comet. Its orbital period is 76 years.
Comet’s Tail Points Away from the Sun
Asteroid Belt
• Most asteroids revolve around the sun
between the orbits of Mars and Jupiter.
• An asteroid is a rocky object that orbits the
sun. Asteroids are too small to be planets.
• Most asteroids are in orbit between Mars
and Jupiter. This region of the solar
system is called the asteroid belt.
• They have orbital periods of three to six
years.
• Most asteroids are less than 1 kilometer in
diameter. Some are much larger.
• Scientists think that asteroids are leftover
pieces of rock from the early solar system.
Irregular Orbits of Asteroids
Meteors
• Meteoroids come from comets or
asteroids.
• A meteoroid is a chunk of rock or dust in
space.
• Some meteoroids form when asteroids
crash into each other. Other meteoroids
form when comets break apart.
• Meteoroids can enter Earth’s atmosphere. When
one does, friction between the meteoroid and
the air produces a streak of light in the sky. A
meteor is a streak of light in the night sky
produced by a meteoroid. (popularly called a
shooting star)
• Most meteoroids burn up completely in Earth’s
atmosphere. However, some hit Earth’s surface.
Meteoroids that hit Earth’s surface are called
meteorites.
Minor Members of the Solar System
Meteoroids
 Most meteoroids originate from any one of
the following three sources:
(1)interplanetary debris that was not
gravitationally swept up by the planets
during the formation of the solar system,
(2) material from the asteroid belt, or
(3) the solid remains of comets that once
traveled near Earth’s orbit.
Major Meteor Showers
video
Ch16 S5 Essential Questions
1. What are the characteristics of comets?
Like a dirty snowball.
Nucleus – center solid part of the comet
Coma – fuzzy cloud of vaporized gases around the nucleus
Tail – stream of dust and gases; always points away from
sun
2. Where are most asteroids found?
Between the orbits of Mars and Jupiter in the asteroid belt
3. What are meteoroids and how do they form?
A chunk of rock or dust in space
Form when asteroids collide in space or when comets
break apart