Across
1
Icy body with a tail near the sun
4
Gas essential for breathing
6
Hottest planet in solar system
7
Absolute temperature scale unit
8
Particle of light
10
Glass that splits light into spectrum
Down
2
Blocking of light by a celestial body
3
Fourth state of matter
5
Nerve cell in the brain
9
The Red Planet
11
Smallest unit of an element