Across
1
Blocking of light by a celestial body
4
Smallest unit of an element
5
Compound containing oxygen
6
Nerve cell in the brain
7
Substance with pH above 7
11
Unit of power
14
Path of a planet around the sun
Down
2
Tissue that contracts for movement
3
Force that attracts objects together
5
Gas essential for breathing
8
Second lightest element
9
Ball of burning gas in space
10
Reddish electrical conductor
12
Infectious microscopic agent
13
Unit of force