This week in 1977, astronomers discovered faint rings around Uranus. Or did they? It’s just possible that William Herschel beat them to it by almost 200 years. Herschel’s notes for February 22, 1789 say ‘A ring was suspected’. It was assumed he was mistaken, but Dr Stuart Eves, inspired by one of our objects, has a theory that could explain Herschel’s observations.
A few years ago, Stuart visited our Blythe House store to see this orrery, or planetary model – the only surviving one of this design.
It shows Uranus with six moons. Herschel discovered the innermost two, Titania and Oberon, in 1787. By 1794 he had reported four additional satellites. However, no other astronomer managed to see them and observations in the 1850s showed Herschel was mistaken and may have been looking at background stars near the planet.
Wanting to know more about this, Stuart studied Herschel’s papers, which is where he found the 1789 reference to the ring, and also one from 1792 referring to ’a very faint ray, like a ring crossing the planet, over the centre’.
So if Herschel did see a ring, how come nobody else managed to until 1977? Well, Stuart’s theory is that if this ring behaves like Saturn’s rings then it might be getting darker and more diffuse, making it harder to see. Plus, the ring is only visible at certain alignments.
But could Herschel really have seen a ring using his 20ft telescope, a giant of the time but diminutive by today’s standards? Well, he built the best telescopes of his era, and was a meticulous observer. So maybe, just maybe… We’ll never know for sure, but it shows what a visit to our stores can trigger!