Egg-Shaped Dwarf Planet Has a Ring Like Neptune

Fagjun | Published 2017-10-24 18:33

Astronomers discover that Haumea, a dwarf planet, can also host a ring. This is a surprising discovery, but it can also cause some trouble for spacecraft in the future.




Haumea is now the first of its kind known to have a ring. The little planet is located over two billion kilometers beyond Pluto in the Kuiper Belt. Haumea is also only the third body smaller than Neptune and the first resident of the Kuiper Belt known to host a ring system. Back in 2013, astronomers discovered that Chariklo, an asteroid-like object called a centaur located between Saturn and Uranus’s orbits, hosts two rings. Another minor planet named Chiron is suspected to have two rings as well.


Further studies on Haumea may give scientists a better idea of how--and why--rings form. However, planetary rings are also now on the list of things that the spacecraft New Horizons has to watch out for.

The Ringed Dwarf Planet

GIF by Stephanie Hoover



“I’m sort of torn,” says SETI planetary scientist Mark Showalter, head of the hazard planning team for New Horizons’s next mission. The spacecraft is set to do a flyby near MU69, an object in the Kuiper Belt. “Scientifically, this is fascinating. But as someone with MU69 on his mind, I did meet the news with some trepidation.”


According to Showalter, the discovery of Haumea’s rings shows that there are things out there that we don’t necessarily expect.


A new study describes how a total of 12 different telescopes in 10 different countries took observations and measurements as Haumea passed between Earth and the star URAT1 533-1825 on January 21, 2017. According to the findings, the starlight of URAT1 533-1825 faded slightly before and after Haumea passed in front of it, indicating the presence of a ring. The measurements indicate that the ring is about 70 kilometers wide and is situated about 2290 kilometers from the center of Haumea.


Haumea is far from being an ordinary, run-of-the-mill rock floating in space. It has several odd characteristics, from its shape to its possession of two moons. These characteristics can tell researchers how and why Haumea managed to form a ring around it in the first place.

Bodies in Space

Haumea and its moons Hi'iaka and Namaka [Image by NASA]



Astronomers say that Haumea rotates like a whirlwind. This may explain why the dwarf planet has an elongated, egg-like shape. It rotates once every three hours and 55 minutes. Compare that to perfectly spherical Pluto, which rotates once every 6.4 Earth days. If you lived on Haumea, you’d see two sunrises and two sunsets each day.


Some time ago, a large object in space may have collided with Haumea. This collision may have caused the dwarf planet to spin rapidly, and may have also sent debris flying away. The debris may formed the two small moons, as well as the ring. A collision with a large object may also explain why Haumea as well as other objects that orbit the sun along the same path have water ice on their surface. It’s possible that they all came from the same single object.


The spacecraft New Horizons won’t be able to study Haumea, but astronomers think they can send another probe Haumea’s way. They hope to find out if planetary rings are more common than previously thought.

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