Across
1
Element found in all living things
3
The Red Planet
5
Path of a planet around the sun
7
Gas essential for breathing
9
Blocking of light by a celestial body
10
Nerve cell in the brain
11
Measure of matter in an object
Down
2
Molten rock beneath Earth surface
4
Particle of light
6
Ball of burning gas in space
8
Biological catalyst