Across
1
Center of an atom or cell
3
Element found in all living things
5
Particle of light
6
Form of thermal energy
9
Ball of burning gas in space
11
Compound containing oxygen
Down
1
Unit of force
2
Blocking of light by a celestial body
3
Reddish electrical conductor
4
Disturbance that transfers energy
7
Mass per unit volume
8
Precious yellow metallic element
10
Path of a planet around the sun