Across
1
Blocking of light by a celestial body
4
Molten rock beneath Earth surface
5
Curved glass that refracts light
7
Particle of light
8
Gas essential for breathing
9
Our home planet
Down
2
Group of similar cells
3
Substance with pH below 7
4
Naturally occurring inorganic solid
6
Reddish electrical conductor
10
Unit of electric potential
11
Precious yellow metallic element
12
Biological catalyst