Across
1
Fourth state of matter
5
Blocking of light by a celestial body
6
Natural satellite of Earth
7
Center of an atom or cell
13
Tectonic landmass section
Down
2
Infectious microscopic agent
3
Molten rock beneath Earth surface
4
Amplified beam of light
8
Unit of electric potential
9
Chemical element in table salt
10
Tissue that contracts for movement
11
Mass per unit volume
12
Curved glass that refracts light