Across
1
Mass per unit volume
4
Blocking of light by a celestial body
5
Form of thermal energy
7
Force that attracts objects together
9
Basic unit of life
Down
2
Preserved remains of ancient life
3
Icy body with a tail near the sun
5
Second lightest element
6
Our home planet
8
Positive particle in nucleus
10
Solid with repeating atomic pattern