ZEITGEIST MOONS
For as long as humans have gazed up into the night sky, our closest celestial neighbour – the Moon – has peered back. So, while Neil Armstrong may have been the first man to step foot on it, cultures have been telling stories about the “man in the Moon” for millennia.
In 1610 we learned that moons aren't unique to Earth when Galileo Galilei pointed a telescope near Jupiter and discovered the first moons away from Earth: the Galilean quartet of Ganymede, Callisto, Io and Europa.
Humankind has made some giant leaps in moon-related knowledge. Recently it was announced that scientists from the Carnegie Institution for Science had discovered a new moon orbiting Uranus – provisionally named S/2023 U1 – and two new moons orbiting Neptune, S/2002 N5 and S/2021 N1. As of May 2024, the current moon count in our Solar System is a whopping 293!
You might be thinking: That's all very well, but what exactly are moons? Let's take a look.
How does a moon differ from a planet?
For a celestialspherical shape. And third, it must have “cleared the neighbourhood” around its orbit. (It's that last criterion that caught out Pluto in 2006, when the International Astronomical Union (IAU) updated its definition of a planet and down-graded Pluto to dwarf-planet status.)
