Across
1
Blocking of light by a celestial body
6
Positive particle in nucleus
7
Chemical element in table salt
8
Center of an atom or cell
9
Unit of power
12
Nerve cell in the brain
Down
2
Icy body with a tail near the sun
3
Gas form of a liquid
4
Absolute temperature scale unit
5
Gas essential for breathing
10
Measure of matter in an object
11
Ball of burning gas in space
13
Basic unit of life