Across
1
Icy body with a tail near the sun
3
Preserved remains of ancient life
6
Amplified beam of light
7
Particle of light
10
Unit of power
11
Glass that splits light into spectrum
Down
2
Center of an atom or cell
4
Biological catalyst
5
Form of thermal energy
8
Mass per unit volume
9
Force that attracts objects together
12
Unit of energy