Across
1
Blocking of light by a celestial body
4
Substance with pH below 7
6
Element found in all living things
7
The Red Planet
8
Mass per unit volume
9
Path of a planet around the sun
Down
2
Center of an atom or cell
3
Amplified beam of light
5
Unit of heredity
10
Tectonic landmass section
11
Unit of power