Across
1
Center of an atom or cell
2
Force that attracts objects together
4
Our home planet
5
Biological catalyst
6
Positive particle in nucleus
10
Preserved remains of ancient life
Down
1
Nerve cell in the brain
3
Fourth state of matter
4
Blocking of light by a celestial body
7
Reddish electrical conductor
8
Naturally occurring inorganic solid
9
Icy body with a tail near the sun