Across
1
Natural satellite of Earth
3
Path of a planet around the sun
5
Second lightest element
7
Unit of heredity
9
Nerve cell in the brain
12
The Red Planet
Down
2
Particle of light
4
Absolute temperature scale unit
6
Molten rock beneath Earth surface
8
Preserved remains of ancient life
10
Solid with repeating atomic pattern
11
Hottest planet in solar system