Across
1
Molten rock beneath Earth surface
4
Blocking of light by a celestial body
5
Curved glass that refracts light
8
Disturbance that transfers energy
9
Gas form of a liquid
10
Our home planet
11
Natural satellite of Earth
12
Substance with pH below 7
Down
2
Second lightest element
3
The Red Planet
5
Amplified beam of light
6
Unit of energy
7
Unit of heredity
13
Nerve cell in the brain