Across
1
Gas essential for breathing
3
Ball of burning gas in space
7
Amplified beam of light
9
Unit of force
10
Icy body with a tail near the sun
11
Tectonic landmass section
12
Basic unit of life
Down
2
Push or pull on an object
4
Group of similar cells
5
Solid with repeating atomic pattern
6
The Red Planet
8
Center of an atom or cell