Across
1
Glass that splits light into spectrum
4
Fourth state of matter
5
Precious yellow metallic element
6
Mass per unit volume
7
Ball of burning gas in space
8
Gas essential for breathing
12
Tectonic landmass section
Down
2
Blocking of light by a celestial body
3
Molten rock beneath Earth surface
9
Path of a planet around the sun
10
Curved glass that refracts light
11
Unit of heredity