Across
1
Blocking of light by a celestial body
4
Center of an atom or cell
5
Measure of matter in an object
6
Ball of burning gas in space
7
Precious yellow metallic element
8
Path of a planet around the sun
9
Basic unit of life
10
Magnetic metallic element
Down
2
Curved glass that refracts light
3
Unit of energy
4
Nerve cell in the brain
11
Group of similar cells