Across
1
Nerve cell in the brain
4
Tectonic landmass section
6
Form of thermal energy
8
Gas essential for breathing
9
Our home planet
12
Biological catalyst
Down
2
Natural satellite of Earth
3
Blocking of light by a celestial body
5
Gas form of a liquid
7
Unit of force
10
Center of an atom or cell
11
Icy body with a tail near the sun