Across
1
Form of thermal energy
3
Unit of electric potential
4
Blocking of light by a celestial body
7
Nerve cell in the brain
9
Measure of matter in an object
Down
1
Second lightest element
2
Path of a planet around the sun
4
Biological catalyst
5
Substance with pH above 7
6
Ball of burning gas in space
8
Glass that splits light into spectrum