Across
1
Path of a planet around the sun
2
Natural satellite of Earth
6
Preserved remains of ancient life
7
Substance with pH below 7
8
Substance with pH above 7
9
Basic unit of life
11
Disturbance that transfers energy
Down
1
Gas essential for breathing
3
Form of thermal energy
4
Push or pull on an object
5
Magnetic metallic element
10
Ball of burning gas in space