Across
1
Force that attracts objects together
4
Blocking of light by a celestial body
5
Naturally occurring inorganic solid
9
Molten rock beneath Earth surface
10
Substance with pH below 7
11
The Red Planet
12
Nerve cell in the brain
Down
1
Precious yellow metallic element
2
Chemical element in table salt
3
Unit of power
6
Unit of force
7
Smallest unit of an element
8
Group of similar cells