Cell division is the process by which a parent cell divides into two or more daughter cells. Cell division usually occurs as part of a larger cell cycle.
Neptune's atmosphere, like Jupiter's and Saturn's, is composed primarily of hydrogen and helium, along with traces of hydrocarbons and possibly nitrogen; it contains a higher proportion of ices such as water, ammonia, and methane.
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. The opposite is true for the upper atmosphere, which contains very few gases heavier than hydrogen and helium due to its low temperature.