Across
1
Center of an atom or cell
4
Our home planet
6
Blocking of light by a celestial body
9
Molten rock beneath Earth surface
13
Second lightest element
Down
2
Curved glass that refracts light
3
Nerve cell in the brain
5
Form of thermal energy
7
Solid with repeating atomic pattern
8
Infectious microscopic agent
10
Unit of energy
11
Unit of power
12
Preserved remains of ancient life