https://github.com/davepinch/pinchy.cc/blob/master/content/camera-roll/2016/10/2016-10-30-reflections-from-the-light-rail.md
Like the gas giants (Jupiter and Saturn), Neptune’s atmosphere is composed primarily of hydrogen and helium, along with traces of hydrocarbons and possibly nitrogen, but contains a higher proportion of ices such as water, ammonia and methane.
