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Asteroids and Comets: Glossary

A

Ammonia
Colorless gaseous compound composed of nitrogen and hydrogen
Asteroid Belt
Collection of asteroids orbiting between Mars and Jupiter
asteroids
Rocky remains from the formation of the solar system
Atmosphere
Gaseous layer surrounding a planet

C

Carbon Dioxide
Colorless, odorless gas – when frozen, known as dry ice
Century
100-year interval
Ceres
Largest asteroid in the asteroid belt
Circumference
Distance around a circular shape – similar to a perimeter
Climate
General weather over a region
Coma
Cloudy envelope around the nucleus of a comet
Comets
Body of gas, ice, and dust that orbits the sun

D

Dawn
NASA space mission to investigate the asteroids Ceres and Vesta
Debris
Junk, garbage
Decade
10-year interval
Dwarf Planet
Small planet

E

Environment
All things surrounding and affecting life

F

Friction
Rubbing of one surface against another

G

Gravitational Pull
Pull of gravity between masses

I

Impact Crater
depression in the ground created by the impact of an asteroid, meteoroid or comet

K

Kuiper Belt
region of space on the edge of our solar system

M

Meteor
A meteoroid that has entered the earth’s atmosphere
Meteorite
The remains of a meteoroid that has fallen to the earth
Meteoroid
Small rocky body traveling through space
Methane
Simple hydrocarbon gas released during decomposition

N

Nucleus
Center of a collection of materials – center of a comet

O

Oort Cloud
region of space beyond Pluto where comets lie

P

Perseid Meteor Shower
In August the earth moves through a field of debris and the resulting meteors that burn up in the atmosphere can be seen

R

Rosetta Mission
International mission between ESA and NASA to study a comet

S

solar system
The sun, planets, moons, asteroids, meteoroids, comets and additional matter between

T

Tail
The venting of gases that show following the heating of a comet by the sun’s energy

V

Vesta
Second most massive asteroid in the asteroid belt
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