Received this from a friend? Sign up here

For now, the new moon is designated S/2025 U 1, but eventually it’ll be named after a character from Shakespeare, like most of the rest of Uranus’s moons. As a side note, please send me your character name suggestions – my colleague Chelsea suggested Mercutio, because “I think of Mercutio as a li’l guy”. I think we should name it Gobbo because he is a side character and therefore also a li’l guy, and Gobbo is extremely fun to say.

… I’ve gotten sidetracked by Shakespeare again. Anyway, S/2025 U 1, also known as Gobbo from now on, was spotted by a team at Southwest Research Institute in Colorado using the James Webb Space Telescope (JWST). It’s circled in the image below.

Credit: NASA, ESA, CSA, STScI, M. El Mou

It’s only about 10 kilometres in diameter, making it the smallest of Uranus’ known moons. That isn’t a surprise: in most of the solar system, and certainly beyond our solar system, the thing stopping us from discovering new moons isn’t a lack of moons but rather a lack of telescope resolution to make out the smallest and dimmest ones. As the researchers behind this discovery told my colleague Matthew Sparkes, there are probably many more moons around Uranus, and the same is true for all the giant planets.

That raises what I think is an interesting question: what counts as a moon? In light of Pluto’s demotion to dwarf planet and the drama surrounding that decision over the past decades, it strikes me as surprising that we have no official definition of a moon. Yes, obviously a moon is something that orbits a planet, but right now there’s nothing stopping me from calling a grain of orbiting dust a moon – and being correct. I wrote about this back in 2019, and nothing has changed since then. At the time, my proposed solution was to define a moon by its mass, and by that rule, Gobbo would be far from making the cut. But Gobbo’s far from making the cut for well-known Shakespeare characters, too, so I guess that’s just another argument for my proposed name.

Credit: SpaceX

After three consecutive and dramatic failed missions, SpaceX has successfully launched Starship to space in a key step for NASA's lunar programme. Read more

The aurora borealis has been remarkably bright recently. Space weather physicist Tamitha Skov reveals what's going on and how worried we should be about a major solar storm. Read more

Astronomers have picked up evidence of an Earth-sized world, distinct from the previously hypothesised Planet Nine and Planet X, that might be warping the orbits of objects beyond Neptune. Read more

A bright flash of radio waves from 3 billion years after the big bang is illuminating parts of the universe that astronomers can’t normally see. Read more

Credit: Andrew McCarthy

This picture of Saturn was taken in the early hours of 19 August as its biggest moon, Titan, passed between the planet and the sun. If you look closely above and to the right of Saturn, you can see Titan, and just below is the moon’s shadow on the planet’s cloud tops. A view like this only comes around for a few weeks once every 15 years, when Saturn’s rings are aligned roughly edge-on to Earth and Titan’s orbit sits just right for us to see its shadow. If you have clear skies and a telescope (you’ll need a medium-sized one for this – binoculars or a spotting scope won’t do), you might be able to catch transits early in the morning on 20 September and 6 October before Titan’s orbit tilts away from us for another 15 years.

John wrote in about a recent article in New Scientist about methane-consuming bacteria that could help mitigate emissions from landfills. He asked: “Could bacteria methanotrophs, mentioned in the article, survive and thrive on Titan with its methane lakes? Maybe it's possible a strain already exists there producing carbon dioxide which could be split into oxygen and may make it more habitable for other organisms.”

The thing about the bacteria in that article is while they consume methane, their cells (like those of all Earth-based organisms) are largely made of water. So a methanotroph would have plenty to eat on Titan, but any Earth-like life would be unlikely to evolve there. And if we dropped a bunch off from here, they’d probably freeze – again, because they’re made of water and the surface temperatures there are far into the negatives. Titan’s just not built for Earth-like life.

But there’s no rule that all life must be Earth-like, so it’s possible there could be organisms elsewhere in the universe made of hydrocarbons like the ones that make up Titan’s rivers and seas. Taking that into account, Titan is possibly the most habitable place in the solar system aside from Earth. I could imagine engineering those microbes to make Titan more habitable to other organisms, or travelling into the distant future to see what they might evolve into, but none of that would really be related to the methanotrophs on Earth.

Credit: Jiawen Chen

Speaking of travelling into the distant future, this month I’ve written a time traveller’s guide to our solar system. If you somehow managed to acquire a time machine, where and when in the history of our solar system would you visit? I’ve put together a list of what I think are the six most important, interesting and generally mind-blowing destinations, including the beginning and end of the solar system and all sorts of wild events in between that have shaped (and will shape) our corner of the cosmos. Dream with me for a second, and have a look. Read more

Thank you for reading! If you have any comments, questions or wild hypotheticals about space, let me know by emailing me at launchpad@newscientist.com and I’ll try to answer them in an upcoming newsletter.

And remember… as far as I can tell, the smallest named moon in the solar system is Aegaeon, a satellite of Saturn that’s less than half a kilometre wide at its narrowest point. It has the mass of about 13 Great Pyramids of Giza, and at a standard walking pace of around 5 kilometres per hour, it’d take about 2.5 hours to walk all the way around it.

Leah Crane
Features editor, New Scientist

Email Leah at launchpad@newscientist.com

Received this from a friend? Sign up here

For the latest science and technology news, in-depth articles and video, visit newscientist.com