Across
1
Substance with pH below 7
3
Preserved remains of ancient life
6
Icy body with a tail near the sun
8
Gas essential for breathing
10
Positive particle in nucleus
11
Our home planet
Down
2
Precious yellow metallic element
4
Blocking of light by a celestial body
5
Amplified beam of light
7
Natural satellite of Earth
9
Absolute temperature scale unit