COMETS, METEORS, AND ASTEROIDS

1
COMETS, METEORS, AND ASTEROIDS
2
Comets
Chunks of ice and dust (dirty
snowball).
Comets _________________________________________
__
When the come close to the Sun, however, the
nucleus is warmed enough by Sunlight to release
gas and dust. These flow away from the nucleus
to produce the ______________ of the comet, which
ALWAYS points away from the ____________.
tail
sun
3
Where do comets come from?

• ________________ beyond the orbit of Pluto
• _________________ beyond the orbit of Neptune

Oort Cloud
Kuiper Belt
4
How do we see new comets?
Passing stars alter the orbits of Oort cloud
comets, causing some of them to enter the
planetary system and become visible as new comets.
A comet loses icy material each time it passes
the ______________. Eventually, the ice is
entirely eroded and the dust particles left
behind from meteoroid swarms that produce
________________________.
sun
Meteor showers
5
METEORS
Meteoroid
________________ a small, metal or rocky debris
left behind in space by a passing
comets. ________________ a meteoroid that has
entered Earths atmosphere and vaporizes, heating
itself and atmospheric gases so that they glow.
Most are no more than 1 cm in diameter. _________
_______ a meteor that has landed on Earths
surface
Meteor
Meteorite
6
Meteorites are classed as stones, irons, and
stony-irons. Stones resemble Earth rocks and are
the most common meteorites.
Carbonaceous chondrites are a type of stony
meteorite and may represent unaltered material
from early in the history of the
__________________. The radioactive elements in
meteorites show that most of them solidified at
almost the same time as the oldest Moon rocks,
about 4.6 billion years ago (age of the Solar
System).
Solar system
The large number of ____________ on the moon and
other Solar System objects indicates that they
experienced an early period of intense
bombardment.
crater
7
ASTEROIDS
Asteroids _______________________________________
________________________________________________
Small, rock bodies in
orbits

• Most orbit between ______________________
• Many are not found in the asteroid belt
• Trojan asteroids, either follow or go before
  Jupiter in its orbit around the Sun.
• Asteroids Hidalgo and Chiron have orbits
  larger than Jupiters.

Mars and Jupiter
www.esa.int/esaCP/ SEMZO8M26WD_index_1.html
8
What would happen if a comet or asteroid were to
strike Earth?

• Serious local and global consequences
• darkness for weeks or months
• very acidic rain
• temporary heating of the atmosphere

Has an asteroid ever hit Earth?
Yes, at the end of the Cretaceous period 65
million years ago. Dinosaur extinctions