Across
1
Form of thermal energy
3
Nerve cell in the brain
4
Blocking of light by a celestial body
5
Positive particle in nucleus
6
Solid with repeating atomic pattern
8
Unit of heredity
Down
1
Second lightest element
2
Compound containing oxygen
3
Center of an atom or cell
4
Our home planet
7
Measure of matter in an object
9
Amplified beam of light