Across
1
Unit of power
3
Mass per unit volume
4
Amplified beam of light
7
Blocking of light by a celestial body
8
Infectious microscopic agent
9
Second lightest element
Down
2
Group of similar cells
5
Tectonic landmass section
6
Fourth state of matter
10
The Red Planet
11
Gas essential for breathing
12
Absolute temperature scale unit