Across
1
The Red Planet
4
Center of an atom or cell
6
Our home planet
8
Nerve cell in the brain
10
Curved glass that refracts light
Down
2
Ball of burning gas in space
3
Mass per unit volume
4
Unit of force
5
Tectonic landmass section
7
Positive particle in nucleus
9
Second lightest element
11
Compound containing oxygen