How Many Moons Does Uranus Have? The Mystery Of The Shakespeare’s Celestial Cast

1st Jan 2025

“Well shone, Moon, truly, the Moon shines with a good grace.” W. Shakespeare “A Midsummer Night’s Dream”

Uranus, the seventh planet from the Sun, and one of the most mysterious planets in the Solar System. This ice giant is known not only for its extreme cold and unusual axis tilt but also for its many satellites, no less mysterious and unique than the planet itself. In this article, we will tell you some interesting facts about the Uranus moons that we are sure you will find surprising.

How Many Moons Of Uranus Are There?

Uranus and its moons — Uranus is surrounded by its moons. Credit: Depositphotos

Uranus has the third-largest number of satellites in the solar system after Jupiter (95) and Saturn (145). For twenty years, the ice giant was the answer to the question – what planet has 27 moons, until in 2023, scientists discovered a new object in its vicinity. So how many moons does Uranus have? As of today, there are 28 confirmed moons of Uranus, but this is not the final verdict. Scientists assume that there may be more. The search continues.

How Did Uranus Get Its Many Moons?

Like the other outer planets, Uranus has a large mass and a strong gravitational field that allows it to capture and hold smaller objects in its orbit. The radius of the gravitational field is determined by the Hill sphere, the region where the planet’s gravity dominates the Sun’s gravity. Simply put, anything that falls within the Hill sphere of an astronomical object becomes its satellite.

Another possibility is that, a long time ago, the planet may have collided with a large asteroid or Earth-sized planet, which knocked the ice giant onto its side. In 2017, astronomers ran a simulation and suggested that this impact may have actually created all of Uranus moons. This hypothesis is supported by their axial tilt, identical to the tilt of the planet’s axis.

Who Discovered The Uranus’ Moons?

William Herschel is considered the discoverer of Uranus and its moons. He discovered the first two in his home telescope in 1787, six years after he discovered the planet itself. Herschel thought he had discovered six satellites, but four turned out to be false. The next two moons were discovered only in 1851 by William Russell. This was possible with the help of improved telescopes and because Uranus was in a favourable position for observation.

The fifth satellite was discovered by Gerard Kuiper in 1948 using a ground-based telescope when scientists were actively searching for new Uranus moons.

Further discoveries became possible only after the start of the Voyager 2 mission. In 1985-1986, the probe flew around Uranus and took detailed pictures of its system, which increased the number of discovered moons to 15!

Uranus and its moons through the James Webb Telescope — Uranus and its moons as seen by the NIRCam (Near-Infrared Camera) on the James Webb Space Telescope. Credit: NASA, ESA, CSA, STScI.

Subsequent observations with ground-based telescopes and the Hubble telescope (1997-2003) allowed scientists to find twelve more satellites of the ice giant. The last satellite to date, the 28th, was discovered in 2023 using the Subaru telescope in Mauna Kea, Hawaii, by a team of astronomers led by Scott Sheppard.

What Are The Three Types Of Uranus Moons?

Uranus moons are divided into three main groups: inner, major, and irregular. This division is due to their distance from the planet and orbital properties.

The inner satellites are 13 small, dark objects with an albedo of no more than 10% that are located inside the Uranian ring system and have an irregular shape. These satellites probably formed from the remnants of material that could not form larger objects.

Major satellites are the five largest moons of the planet, although together, they are smaller than Triton, the largest satellite of Neptune. Uranus’ largest satellite, Titania, is 1,578 km in diameter and is 20 times less massive than Earth’s moon. However, the mass of the major satellites is enough to ensure that they have stable orbits and a spherical shape due to their gravity.

The location of the 5 major satellites of Uranus. Credit: 3dwarehouse

The irregular moons of Uranus are located at a considerable distance from the planet and have an irregular shape. Their orbits are highly elongated and inclined, which makes them unstable and subject to change under the influence of gravitational interactions with other satellites and planets.

What Are Uranus’ Moons Made Of?

All of Uranus moons are composed primarily of ice, like the planet itself. The inner satellites contain water ice and a small admixture of dark material, possibly radiation-modified organic matter. The four large satellites have a rocky core surrounded by a shell of ammonia and carbon dioxide ice. The composition of the irregular satellites is unknown due to the difficulty of studying them. It is assumed that they may be stony-iron asteroids from the Kuiper Belt, attracted by the gravity of the ice giant.

Is There Anything Special About The Moons Of Uranus?

Alexander Pope and William Shakespeare. Collage.

Most astronomical objects in the solar system get their names from the mythologies of ancient Greece and Rome. The Uranus moons are unique since they are named after characters from poems by William Shakespeare and Alexander Pope. This tradition was started in 1857 by William Herschel’s son and a great admirer of Shakespeare’s works, John Herschel. Before that, all of Uranus moons were simply numbered with Latin numerals.

Herschel named the first satellites he found after spirits: the king and queen of the fairies and elves Oberon and Titania from Shakespeare’s A Midsummer Night’s Dream and the sylphs Ariel and Umbriel from Pope’s The Rape of the Lock (Ariel is also an elf from Shakespeare’s The Tempest). In his choice, the scientist was probably guided by the fact that, as the god of the sky and air, Uranus is accompanied by air spirits.

Herschel’s tradition was continued by Gerard Kuiper in 1948. He named the 5th satellite Miranda, after a character in Shakespeare’s The Tempest. And a year later, the International Astronomical Union (IAU) made an official decision to name all new Uranus moons after characters in the works of William Shakespeare and Alexander Pope’s poem The Rape of the Lock.

Which Planet Moons Are Named After Shakespearean Characters?

To date, 24 moons of Uranus are named after characters by William Shakespeare and three more after characters by Alexander Pope. In the table below, you can see their names and which plays they are taken from.

№	Name of Moon	Shakespearean Play or Alexander Pope’s Poem	Year of Discovery	Discoverer	Type
1	Titania	“A Midsummer Night’s Dream”	1787	William Herschel	Major
2	Oberon	“A Midsummer Night’s Dream”	1787	William Herschel	Major
3	Ariel	“The Tempest”	1851	William Lassell	Major
4	Umbriel	“The Rape of the Lock” (Alexander Pope)	1851	William Lassell	Major
5	Miranda	“The Tempest”	1948	Gerard Kuiper	Major
6	Cordelia	“King Lear”	1986	Voyager 2	Inner
7	Ophelia	“Hamlet”	1986	Voyager 2	Inner
8	Bianca	“The Taming of the Shrew”	1986	Voyager 2	Inner
9	Cressida	“Troilus and Cressida”	1986	Voyager 2	Inner
10	Desdemona	“Othello”	1986	Voyager 2	Inner
11	Juliet	“Romeo and Juliet”	1986	Voyager 2	Inner
12	Portia	“The Merchant of Venice”	1986	Voyager 2	Inner
13	Rosalind	“As You Like It”	1986	Voyager 2	Inner
14	Cupid	“The Rape of the Lock” (Alexander Pope)	2003	Voyager 2	Inner
15	Belinda	“The Rape of the Lock” (Alexander Pope)	1986	Voyager 2	Inner
16	Perdita	“The Winter’s Tale”	1986	Voyager 2	Inner
17	Puck	“A Midsummer Night’s Dream”	1985	Ground-based	Irregular
18	Mab	“Romeo and Juliet”	2003	Ground-based	Irregular
19	Francisco	“Hamlet”	2001	Ground-based	Irregular
20	Caliban	“The Tempest”	1997	Ground-based	Irregular
21	Stephano	“The Tempest”	1999	Ground-based	Irregular
22	Trinculo	“The Tempest”	2001	Ground-based	Irregular
23	Sycorax	“The Tempest”	1997	Ground-based	Irregular
24	Margaret	“Much Ado About Nothing”	2003	Ground-based	Irregular
25	Prospero	“The Tempest”	1999	Ground-based	Inner
26	Setebos	“The Tempest”	1999	Ground-based	Inner
27	Ferdinand	“The Tempest”	2001	Ground-based	Irregular
28	S/2023 U1		2023	Scott S. Sheppard	Irregular

Table 1. The moons of Uranus: names, from which poems they are taken, who and when discovered, types.

The 28th moon, discovered in November 2023, has not yet received its official name. It is temporarily designated S/2023 U1 but will also be named after a character from one of the great English playwrights.

Could Uranus Have Any Undiscovered Moons?

Uranus’ brightest ring, epsilon, is kept in place by two moons, Cordelia and Ophelia. New evidence suggests the alpha and beta rings may also have moonlets keeping them in place. Credit: NASA.

The more our capabilities for space exploration increase, the more confident scientists grow in their assumptions that there may be undiscovered objects orbiting Uranus, especially among the irregular satellites in the planetary ring system. Such satellites are extremely difficult to detect due to their small size, low albedo, and highly elongated orbits, which are often retrograde.

University of Idaho researchers Rob Chancia and Matt Hedman analysed images taken by Voyager 2 in 1986 and noticed that the amount of material at the edge of the alpha ring, the brightest of the Epsilon rings, varied periodically. A similar pattern was also found in the beta ring. The scientists speculate that these may be small satellites, 4 to 14 km in diameter, called “moonlets.” The moonlets may act as shepherds, helping to keep the rings from spreading out. If these satellites do exist, they could help explain some characteristics of Uranus’s rings, which are oddly narrow compared to Saturn’s rings.

Revealing The Mystery Of The Shakespeare’s Celestial Cast

The tradition of naming the moons of Uranus after characters from the immortal works of William Shakespeare and Alexander Pope is certainly unique, creating a rich fabric that connects the worlds of literature and astronomy. This magnificent celestial cast not only carries the cultural legacy of British literature but also adds to the fascination of space exploration. As we delve deeper into the mysteries of these distant satellites, we are reminded of the timeless power of storytelling and its ability to inspire scientific discovery. May Shakespeare’s moon favour us in this endeavour.