Our solar system may be small compared to the universe, but amazingly it is still producing new discoveries.
Scientists have discovered three new moons: two orbiting Neptune and one orbiting Uranus.
Uranus’ new moon – the first discovered around the planet in more than two decades – is likely the smallest, measuring just eight kilometers in diameter.
Meanwhile, Neptune’s two new moons include the faintest moon ever discovered by ground-based telescopes.
They bring the total number of known moons of Neptune to 16, while Uranus now has 28, although this is still modest compared to the solar system’s two largest planets.
The Uranian moon S/2023 U1. Uranus is just outside the field of view at the upper left, as evidenced by the increased scattered light
Pictured: Uranus (left) and Neptune (right). Uranus and Neptune, the seventh and eighth planets, are the only two ice giants in the outer solar system
Jupiter has 95 moons and Saturn a whopping 146 – and this number is rising regularly.
Dr. Scott S. Sheppard, an astronomer at the Carnegie Institution for Science, led the discovery of the three new moons.
More than 50 million kilometers away, they orbit the two most distant planets in our solar system.
“The three newly discovered moons are the faintest ever found around these two ice giant planets using ground-based telescopes,” he said.
‘Special image processing was required to make such faint objects visible.’
Uranus’ new moon is tentatively named S/2023 U1, but will eventually be named after a character from a Shakespeare play, in keeping with naming conventions for Uranian moons.
It was first spotted last November by Dr Sheppard using the Magellan telescopes at Carnegie Science’s Las Campanas Observatory in Chile.
With a diameter of only about 8 km, it is probably the smallest of Uranus’s moons in existence, and it takes 680 days to orbit the planet.
Sheppard also used the Magellan telescope to find the brighter of Neptune’s two newly discovered moons, tentatively named S/2002 N5.
It is about 23 km in diameter and takes almost nine years to orbit the ice giant.
Depicted are the known outer moons of the giant planets. The new Uranian (pink) and Neptunian (blue) discoveries are shown as solid symbols
S/2023 U1 was first spotted on November 4, 2023 by Sheppard using the Magellan telescopes at Carnegie Science’s Las Campanas Observatory in Chile (photo)
Meanwhile, the fainter Neptunian moon, S/2021 N1, is about 9 miles across and has an orbit of nearly 27 years, and was found using the Subaru Telescope in Hawaii.
Both will have permanent names based on the 50 Nereid sea goddesses from Greek mythology.
All three moons have distant and “eccentric” orbits, meaning their orbit around their planet is not perfectly circular.
They were captured by the gravity of these planets during or shortly after Uranus and Neptune formed from the ring of dust and debris that surrounded our Sun in its infancy.
Earth’s only moon was probably formed when a large body the size of Mars collided with Earth, throwing much of our planet’s material into orbit.
According to NASA, there are likely thousands more moons in our solar system waiting to be discovered.
Even the most powerful ground-based telescopes are often small enough to see too dimly.
Even satellites sent more than a billion kilometers to the outer planets can miss the moons, depending on where they are in their orbit.
It was in 1989 that NASA’s Voyager 2 spacecraft provided the first close-up images of Neptune, although Neptune is actually a lighter shade of greenish-blue than this image suggests
Uranus and Neptune, the seventh and eighth planets in our solar system, are the only two ice giants in the outer solar system.
They consist mainly of a hot, dense liquid of ice-cold materials – water, methane and ammonia – above a small rocky core.
Scientists recently revealed new images of what both planets actually look like, claiming that previous photos misrepresent their true colors.
Neptune is known as deep blue and Uranus green, but the color of the two ice giants is actually much closer than commonly thought.
Neptune is actually pale blue-green or “cyan,” similar to Uranus and much lighter than the famous deep blue in images from the Voyager 2 spacecraft.