Across
1
Path of a planet around the sun
4
Nerve cell in the brain
5
The Red Planet
9
Form of thermal energy
10
Compound containing oxygen
11
Curved glass that refracts light
Down
2
Glass that splits light into spectrum
3
Group of similar cells
6
Magnetic metallic element
7
Natural satellite of Earth
8
Our home planet
12
Ball of burning gas in space