Download Comets, Asteroids, and Meteors

Comets, Asteroids, and
Meteors
Chapter 14.5
Page 572
Comets
• Often, we refer to comets as dirty
snowballs…this is because
– Comets are chunks of ice and dust whose
orbits are usually very long, narrow ellipses.
The inner core of the
comet is called the
nucleus.
The comet’s head is
called the coma.
The tail of the comet
is composed of gas
and dust being
pushed away from
the coma.
nucleus
tail
coma
Comets
Because their orbits are so elliptical, few pass near
Earth and when they do they are only seen briefly.
• Since comets have an orbit, we usually will see the
same comet every several years. Ex: Haley’s comets
passes by Earth every 76 years. Last seen: 1986, next
seen 2062.
– When a comet gets to close to the sun, the energy
from the sunlight turns the ice into gas, releasing
the dust.
– The dust and gas form the outer layer called the
coma.
Origin of Comets
• Most comets originate from one of two
distant regions: the Kuiper belt or the
Oort cloud
Kuiper Belt
Oort Cloud
Asteroids
• Asteroids are objects that are too small
and numerous to be called planets.
• Most asteroids revolve around the sun
between the orbits of Mars and Jupiter.
– This region is known as the asteroid belt.
• Some asteroids come near the orbit of
Earth. (Five actually revolve Earth)
• Asteroids that impact on Earth can cause
great devastation depending on its size.
Origin of Asteroids
• Theory 1: Asteroids are the remains of a
shattered planet.
• Theory 2: Asteroids are left over pieces of
the early solar system that never came
together.
Meteors
• A meteoroid is a chunk of rock or dust in space.
– Meteoroids usually come from remains of comets or
asteroids.
– When a comet breaks up, the cloud of dust continues
to move through the solar system.
– When Earth passes through this cloud of dust, bits of
dust enter Earth’s atmosphere.
• When a meteoroid passes through Earth’s
atmosphere, friction makes it burn up and
produce a streak of light…this is a meteor.
• Meteoroids that pass through Earth’s
atmosphere and hit Earth’s surface are called
meteorites.
Other “shooting stars” …
Homework
• Read Section 5 of Chapter 14
• Answer the Assessment Questions on
page 575.