Article image

Three new moons discovered around Neptune and Uranus

In the vast expanse of the cosmos, our solar system might seem like a mere speck, yet it continues to reveal new wonders. Recently, astronomers announced the discovery of three additional moons: two in orbit around Neptune and one circling Uranus. 

Uranus and Neptune, the solar system’s ice giants, are composed primarily of a dense fluid of icy materials such as water, methane, and ammonia, above a small rocky core. 

A new perspective 

Recent imagery has corrected misconceptions about their appearance, showing that both planets are more similar in color than previously thought. Contrary to the deep blue images captured by Voyager 2, Neptune’s true color is a pale bluish-green, closely resembling Uranus, and offering a new perspective on these distant worlds.

Three new moons 

The newly identified moon of Uranus, which is the first discovery of its kind in over two decades, is believed to be the planet’s smallest, with a diameter of merely five miles. The discoveries at Neptune include the dimmest moon ever detected with ground-based telescopes.

With these findings, Neptune’s tally of moons increases to 16, and Uranus’ count to 28, though these numbers pale in comparison to the moon collections of Jupiter and Saturn, the solar system’s largest planets, which boast 95 and 146 moons, respectively, with numbers that continue to grow.

Special image processing 

The team, led by Dr. Scott S. Sheppard from the Carnegie Institution for Science, identified these celestial bodies orbiting the solar system’s two furthest planets, more than 30 million miles away. 

“The three newly discovered moons are the faintest ever found around these two ice giant planets using ground-based telescopes,” Sheppard said. “It took special image processing to reveal such faint objects.” 

Smallest moon of Uranus 

The Uranian moon, temporarily named S/2023 U1, awaits a permanent name that will align with the tradition of naming Uranus‘ moons after characters from Shakespeare’s works.

Dr. Sheppard, utilizing the Magellan telescopes at the Las Campanas Observatory in Chile, first observed this moon in November of the previous year. The moon, approximately five miles in diameter, orbits Uranus every 680 days, making it potentially the smallest moon of Uranus.

Neptune’s moons

The brighter of the two new Neptunian moons, provisionally named S/2002 N5, discovered using the same telescope, measures about 14 miles across and completes an orbit in nearly nine years. 

The other, a dimmer moon named S/2021 N1, discovered with the Subaru telescope in Hawaii, has a diameter of approximately 8.5 miles and an orbital period of nearly 27 years. These moons will eventually be named after one of the 50 Nereid sea goddesses from Greek mythology, following naming conventions for Neptunian moons.

Many more moons remain undetected

The moons are characterized by distant and eccentric orbits, suggesting they were captured by the gravitational pull of Uranus and Neptune during or shortly after the planets’ formation from the protoplanetary disk surrounding the early Sun. Earth’s moon, by contrast, likely formed from the debris ejected after a Mars-sized body collided with Earth. 

NASA believes thousands more moons await discovery within our solar system, though many remain elusive due to their small size and the limitations of even the most powerful telescopes. Moreover, spacecraft sent to explore the outer planets often miss these moons, depending on their position in their orbits.

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates.


Check us out on EarthSnap, a free app brought to you by Eric Ralls and

News coming your way
The biggest news about our planet delivered to you each day