Across
1
Absolute temperature scale unit
4
The Red Planet
5
Preserved remains of ancient life
7
Element found in all living things
10
Ball of burning gas in space
12
Blocking of light by a celestial body
Down
2
Substance with pH above 7
3
Gas essential for breathing
6
Amplified beam of light
8
Fourth state of matter
9
Naturally occurring inorganic solid
11
Substance with pH below 7