Across
1
Force that attracts objects together
3
Natural satellite of Earth
4
The Red Planet
7
Blocking of light by a celestial body
12
Compound containing oxygen
Down
2
Glass that splits light into spectrum
5
Precious yellow metallic element
6
Icy body with a tail near the sun
8
Preserved remains of ancient life
9
Fourth state of matter
10
Unit of force
11
Unit of energy