Across
1
Blocking of light by a celestial body
3
Path of a planet around the sun
6
Reddish electrical conductor
9
Glass that splits light into spectrum
10
Substance with pH above 7
11
Natural satellite of Earth
12
Unit of electric potential
Down
2
Preserved remains of ancient life
4
Mass per unit volume
5
Force that attracts objects together
6
Basic unit of life
7
Form of thermal energy
8
Particle of light