Across
1
Precious yellow metallic element
4
Icy body with a tail near the sun
5
Nerve cell in the brain
6
Magnetic metallic element
10
Particle of light
11
Absolute temperature scale unit
Down
2
Gas essential for breathing
3
Amplified beam of light
7
Naturally occurring inorganic solid
8
The Red Planet
9
Blocking of light by a celestial body
12
Curved glass that refracts light