Astronomers have made an exciting discovery, finding two new moons orbiting Neptune and one circling Uranus. This brings the total count of known moons around Neptune to 16 and around Uranus to 28. The newfound moon around Uranus is the first detected in over two decades and is believed to be the smallest of its kind, measuring just 5 miles (8 kilometers) wide. It takes 680 days to complete one orbit around Uranus, making it a fascinating addition to the planet’s moon system.
In comparison, one of Mars’ moons named Deimos, which is considered to be among the tiniest known moons in our solar system, is 8 miles (13 km) wide. The new moon around Uranus is currently referred to as “S/2023 U1” and is awaiting a name based on a Shakespearean character, according to the Carnegie Institution for Science.
Moving on to Neptune, astronomers have discovered two new moons. The brighter of the two is provisionally named “S/2002 N5” and measures 14 miles (23 km) wide. It appears to be in a 9-year orbit around Neptune. The fainter moon, currently known as “S/2021 N1,” is 8.6 miles wide (14 km) and takes approximately 27 years to complete one orbit around Neptune. Both of these Neptunian moons will eventually be given permanent names based on sea gods and nymphs in Greek mythology.
The announcement of these three new moons was made by the International Astronomical Union’s Minor Planet Center, a scientific body responsible for designating planets, comets, and moons in our solar system. The discovery was made using observatories in Hawaii and Chile by a team of scientists including Scott Sheppard from Carnegie Science, Marina Brozovic and Bob Jacobson from NASA’s Jet Propulsion Laboratory (JPL), David Tholen from the University of Hawaii, Chad Trujillo from Northern Arizona University, and Patryk Sofia Lykawa from Kindai University.
According to Sheppard, these new moons are the faintest ever found around Uranus and Neptune using ground-based telescopes. It required special image processing techniques to reveal such faint objects. Sheppard first detected the new moon around Uranus in November of last year while using Chile’s Magellan telescopes. Follow-up observations and predictions by JPL scientists confirmed the find.
The two new moons around Neptune were first observed in September 2021. The orbit of the brighter moon, S/2002 N5, was traced back to an object that was spotted near Neptune in 2003 but was lost before it could be confirmed as orbiting the planet. Determining the orbit of the fainter Neptunian moon required special observing time under ultra-pristine conditions with Europe’s Very Large Telescope in Chile and Gemini Observatory in Hawaii.
To capture images of these faint moons, Sheppard and his colleagues took a series of five-minute exposures over three-to-four-hour periods using the telescopes. These short-burst images were then layered to bring the newfound moons into clearer view. All three moons have egg-shaped orbits that are highly inclined to the plane of their respective ice giants, suggesting that they were not formed around their host planets but were instead captured later on through gravitational forces.
This discovery adds to our understanding of the moon systems around Uranus and Neptune and provides valuable insights into the formation and evolution of these distant planets. As astronomers continue to explore our solar system, we can expect more exciting discoveries that will expand our knowledge of the universe we live in.