Across
1
Disturbance that transfers energy
4
Path of a planet around the sun
6
Second lightest element
7
Blocking of light by a celestial body
8
Preserved remains of ancient life
9
Unit of electric potential
12
Reddish electrical conductor
13
Unit of heredity
Down
2
Group of similar cells
3
The Red Planet
5
Smallest unit of an element
10
Gas essential for breathing
11
Magnetic metallic element