Across
1
Compound containing oxygen
5
Blocking of light by a celestial body
6
Magnetic metallic element
7
Ball of burning gas in space
9
Our home planet
Down
2
Center of an atom or cell
3
Naturally occurring inorganic solid
4
Gas form of a liquid
8
Gas essential for breathing
10
The Red Planet
11
Infectious microscopic agent
12
Substance with pH below 7