Across
1
Force that attracts objects together
4
Unit of energy
6
Center of an atom or cell
9
Ball of burning gas in space
10
Unit of electric potential
Down
2
Blocking of light by a celestial body
3
Tectonic landmass section
5
Mass per unit volume
7
Amplified beam of light
8
Path of a planet around the sun
11
Disturbance that transfers energy