Across
1
Particle of light
4
Naturally occurring inorganic solid
5
Hottest planet in solar system
6
Icy body with a tail near the sun
7
Substance with pH above 7
8
Blocking of light by a celestial body
9
Chemical element in table salt
Down
1
Fourth state of matter
2
Mass per unit volume
3
Center of an atom or cell
10
Smallest unit of an element