Across
1
Force that attracts objects together
4
Basic unit of life
5
Curved glass that refracts light
8
Measure of matter in an object
9
Ball of burning gas in space
10
Amplified beam of light
Down
2
Unit of electric potential
3
Path of a planet around the sun
4
Solid with repeating atomic pattern
6
Glass that splits light into spectrum
7
Preserved remains of ancient life
11
Tissue that contracts for movement
12
Center of an atom or cell