Haumea: The Only Dwarf Planet With a Ring Around It

By: Jesslyn Shields  | 
Scientists have identified a ring circling Haumea, an egg-shaped dwarf planet (relatively) near Pluto, shown in this artist's illustration. JM Madiedo, JL Ortiz/IAA-CSIC

There's a lot going on just outside of our solar system, planet-wise. Sure, there's the dwarf planet Pluto lurking out there beyond Neptune. But there's more than that one, demoted, little former planet hanging out in the Kuiper belt, the disc of space rubble that orbits our sun.


Haumea Is One of Five Dwarf Planets

In fact, in addition to an unfathomable number of asteroids and chunks of frozen gases, Pluto is one of five dwarf planets that have been identified. It has four dwarf planet friends out there: Haumea, Makemake, Eris and Ceres. Haumea and Makemake are part of the Kuiper belt. Eris orbits out beyond Neptune but is not part of the Kuiper belt. The fifth dwarf planet, Ceres, lies in the main asteroid belt between Mars and Jupiter. There may, of course, be more mini worlds out there, but for now these are the ones we know about.

Planets, as we know, sometimes have rings made out of chunks of rock and ice — Saturn's got the most famous one, and Jupiter, Uranus and Neptune have them, too. But the dwarf planet Haumea, a little oblong chunk of rock that lies 50 times farther away from the sun than Earth, is the only official dwarf planet ringed by its own collection of orbiting space particles. It's also the only trans-Neptunian object — a planet-like object that orbits the sun from a distance equal or greater to that of the planet Neptune — known to have a ring.


The dwarf planet's existence was initially catalogued in 2003 and it was designated 2003 EL61. Haumea was classified as a Kuiper belt object (KBO) and officially recognized by the International Astronomical Union (IAU) in 2008. It was then reclassified as the fifth dwarf planet in the solar system, taking its place beside Ceres, Pluto, Eris and Makemake. It was renamed after the Hawaiian goddess of childbirth and fertility, Haumea, and its two moons named for her daughters, Hi'iaka and Namaka.

An Unconventional Part of the Kuiper Belt

Situated in the Kuiper belt, a region beyond Neptune filled with icy bodies and remnants from the solar system's formation, Haumea's intriguing characteristics start with its unusual shape. Haumea is a rapidly rotating solar system objet that takes just under four hours to complete a rotation. This high rotational speed has given it an oblong or ellipsoidal shape rather than the usual spherical form seen in many other celestial bodies.

Despite its icy surface, Haumea is mainly composed of rock, distinguishing it from many other Kuiper belt objects. The icy shell is primarily made of crystalline water ice, a feature that is quite unusual for icy bodies in the outer reaches of the solar system, where temperatures typically lead to the formation of amorphous ice.


This is a 3D illustration of ringed dwarf planet Haumea, with its two moons, Hi'iaka and Namaka.
SN VFX/Shutterstock

The Discovery of Haumea's Ring

A study published in the October 2017 journal Nature reported the discovery of Haumea's ring. In January 2017, a team of researchers from Spain's Institute of Astrophysics of Andalusia (IAA-CSIC) trained 12 telescopes from 10 different European observatories at a star they knew Haumea would pass in front of. When the dwarf planet moved in front of the star, they expected to be able to get a good look at Haumea's size, shape and rotational speed. They did, but they also spotted a ring.

There are different possible explanations for the formation of the ring," said lead author José Luis Ortiz, a researcher at the IAA-CSIC, in a press release. "It may have originated in a collision with another object, or in the dispersal of surface material due to the planet's high rotational speed."


The scientists also found dwarf planet Haumea to be much bigger, less dense and less reflective than they suspected. The egg-shaped Haumea, when measured along its largest axis, is about as long as Pluto is round. But unlike Pluto, Haumea lacks the global atmosphere of that erstwhile ninth (non-)planet. And the researchers think that presence of the ring, which circles Haumea about 1,421 miles (2,287 kilometers) from its equator at a speed three times slower than the planet's own rotation, might mean similar rings could be much more common in our solar system than previously thought. Because of its fast rotation, a day on Haumea lasts 3.9 hours, one of the shortest days in the solar system.

What's more, scientists have identified a mysterious dark red spot on Haumea's surface. The origins of this spot remain a subject of research, with possibilities ranging from organic compounds or minerals to a higher concentration of crystalline ice. The tint could result from a local concentration of red-reflecting organic compounds or blue-absorbing minerals on the icy surface of Haumea. Scientists at NASA's Goddard Space Flight Center in Greenbelt, Maryland, are continuing to study the dwarf planet to understand the chemical and physical processes that shaped it.


Composition and Physical Processes: Unraveling the Mysteries of Haumea

Unlocking the secrets of the young dwarf planet's composition and physical processes will provide valuable insights into our solar system's early days. As a Kuiper belt dwarf planet, Haumea is a testament to the diverse and intriguing world of KBOs. The speed at which this young dwarf planet rotated during its formative years likely played a crucial role in determining its current shape, composition and perhaps even the formation of its moons and rings.

Our exploration of Haumea, along with other icy bodies in the Kuiper belt, will continue to challenge our understanding of planetary formation and the chemical and physical processes that define the celestial bodies. Haumea, with its peculiar shape, intriguing composition, moons and ring system, adds a captivating chapter to the ongoing narrative of space exploration. As we continue to learn more about Haumea and other KBOs, we come to appreciate the diversity and complexity of our solar system. This journey of discovery not only illuminates our past but also helps chart the course of our future voyages into the vast cosmos.


This article was updated in conjunction with AI technology, then fact checked and edited by a HowStuffWorks editor.