Neptune is the windiest world we know — supersonic storms tear through its methane skies at over 2,000 km/h. It was the first planet found by mathematics rather than chance: astronomers predicted its position from the way its gravity tugged on Uranus, then pointed a telescope and found it almost exactly there in 1846.

At magnitude 7.8 Neptune is never visible to the naked eye — you need binoculars or a telescope and a good chart. Even then it shows only a small, steady blue dot, its colour the giveaway that distinguishes it from background stars. It completed its first full orbit since discovery only in 2011.