(The Moon is currently about 384,000 km or 60 Earth radii away from Earth, which is about fifteen times further away than it was when it first formed.) The Moon probably couldn't have formed closer than 3 Earth radii because tidal forces from the Earth would just pull it apart again, and it is unlikely that the impact could have ejected material ...
About 78% of Earthâs atmosphere is made up of nitrogen. Credit: NASA We might commonly think of Earth as having an oxygen-dominated atmosphere, but in reality the molecule makes up only a fifth of our air.
Uranus by Voyager 2. The atmosphere of Uranus, like those of the larger gas giants, Jupiter and Saturn, is composed primarily of hydrogen and helium. At depth it is significantly enriched in volatiles (dubbed ices) such as water, ammonia and methane.he opposite is true for the upper atmosphere, which contains very few gases heavier than hydrogen and helium due to its low temperature. Uranus's atmosphere is the coldest of all the planets, with its temperature reaching as low as 49 K.