Across
1
Blocking of light by a celestial body
6
Ball of burning gas in space
7
Naturally occurring inorganic solid
9
Mass per unit volume
Down
2
Precious yellow metallic element
3
Infectious microscopic agent
4
Particle of light
5
Unit of energy
8
Force that attracts objects together
10
Center of an atom or cell
11
Unit of power
12
Compound containing oxygen