Across
1
Glass that splits light into spectrum
3
Unit of force
5
Icy body with a tail near the sun
8
Gas form of a liquid
9
Preserved remains of ancient life
10
Form of thermal energy
11
Blocking of light by a celestial body
12
Center of an atom or cell
Down
1
Positive particle in nucleus
2
Molten rock beneath Earth surface
4
Reddish electrical conductor
6
Second lightest element
7
Our home planet
8
Hottest planet in solar system