Across
1
Positive particle in nucleus
3
Blocking of light by a celestial body
4
Naturally occurring inorganic solid
5
Substance with pH below 7
7
Curved glass that refracts light
8
Path of a planet around the sun
10
Preserved remains of ancient life
Down
2
Element found in all living things
3
Biological catalyst
6
Force that attracts objects together
8
Compound containing oxygen
9
Unit of heredity