Astronomers have found three previously unknown moons in our solar system; two additional moons circling Neptune and one around Uranus, the International Astronomical Union’s Minor Planet Centre have announced.
The three new moons are the faintest moons ever, found around Neptune and Uranus using ground-based telescopes with special image processing to reveal them.
S/2023 U1 is believed to be the smallest of Uranus’ moons at only 8km wide and takes 680 days to complete an orbit of the planet.
The new Uranian moon, provisionally named S/2023 U1, is awaiting its official name which will be that of a character from a Shakespeare play, keeping in the nomenclature tradition for Uranian moons.
S/2023 U1 is believed to be the smallest of Uranus’ moons at only 8km wide and takes 680 days to complete an orbit of the planet. S/2023 U1 was first spotted on the 4th November 2023 by Scott S. Sheppard using the Magellan telescopes at the Carnegie Science’s Las Campanas Observatory in Chile, with Sheppard making additional observations in the following December.
The Magellan Telescope was also used by Sheppard to find the brighter of the two Neptunian moons, provisionally named S/2002 N5 is approximately 23km in size and requires 9 years to complete an orbit around Neptune.
This moon’s orbit of Neptune had been determined using 2021, 2022 and 2023 observations, and was traced back to an object observed near Neptune in 2003 but had been lost before it could be confirmed as orbiting the planet according to Sheppard
Sheppard's collaboration with David Tholen of the University of Hawaii, Chad Trujillo of Northern Arizona University, and Patryk Sofia Lykawa of Kindai University resulted in the finding of the second Neptunian moon.
The moon is now provisionally named S/2021 N1, approximately 14km wide with an orbit completion time of nearly 27 years.
In line with Neptunian moon nomenclature tradition, the two new moons will receive permanent names based on the 50 Nereid Sea goddesses in Greek mythology.