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.
Like Jupiter and Saturn, Neptune is one of the 'gas giant' planets, composed of a deep atmosphere around a liquid surface and sometimes a solid core. Its atmosphere consists of mostly hydrogen and helium, but up to three percent of its atmosphere is made up of methane, which gives the planet its striking blue colour. There are several cloud features, the most prominent being the great dark spot, a huge storm system which is as big as the Earth.