Across
1
Blocking of light by a celestial body
4
Unit of power
6
Particle of light
10
Force that attracts objects together
12
Disturbance that transfers energy
Down
2
Curved glass that refracts light
3
Ball of burning gas in space
5
Substance with pH above 7
7
Basic unit of life
8
Natural satellite of Earth
9
Smallest unit of an element
11
Unit of electric potential