Across
1
Absolute temperature scale unit
3
Path of a planet around the sun
4
Particle of light
6
Gas essential for breathing
7
Nerve cell in the brain
9
Push or pull on an object
11
Fourth state of matter
Down
2
Blocking of light by a celestial body
3
Compound containing oxygen
5
Basic unit of life
8
Unit of electric potential
10
Gas form of a liquid
12
Glass that splits light into spectrum
13
Unit of heredity