Across
1
Magnetic metallic element
3
Second lightest element
4
Ball of burning gas in space
9
Center of an atom or cell
10
Particle of light
11
Hottest planet in solar system
Down
2
Naturally occurring inorganic solid
5
Reddish electrical conductor
6
Blocking of light by a celestial body
7
Group of similar cells
8
Absolute temperature scale unit