Published: Thu, October 12, 2017
Research | By Raquel Erickson

This weirdo dwarf planet has a ring around it

This weirdo dwarf planet has a ring around it

Named after the Hawaiian goddess of childbirth, it is among a handful of known dwarf planets beyond the orbit of Neptune, which with the other so-called giant planets - Saturn, Uranus and Jupiter - all have rings.

The peculiar dwarf planet Haumea has just gotten more peculiar with the discovery of some faint rings around it. The term "dwarf planet" probably brings to mind bodies like Pluto - flawless spheres that only just miss out on true planethood.

It wasn't just rings that the team were looking out for however, as it also gave astronomers an opportunity to analyse its shape, and it could be about to jeopardise its status as a dwarf planet.

This suggested something was obscuring it, most likely a series of rings, that was only confirmed after many months of follow-up research by a team led by José Luis Ortiz of the Instituto de Astrofísica de Andalucía. The team hoped to learn more about the size and shape of the dwarf planet because the distance of that star from Haumea was so vast that its shadow appeared at regular size. In fact, it might be taken out of the "dwarf planets list" that the astronomers composed. The total number of officially recognised dwarf planets is now five, but some astronomers argue there could be hundreds of objects in the solar system that fit the definition. At that moment, using 12 telescopes from 10 different laboratories, the researchers could see that the dwarf planet was joined with other materials.

Two minor planets closer than Neptune have rings: the 250-km-wide Chariklo and Chiron, both orbiting "between the asteroid belt and Kuiper belt", the Planetary Society says.

Hydrostatic equilibrium is the scientific way of saying that a lump of rock is so big its own gravity has pulled it all in and made it spherical, or at least an ellipsoid. But it's too soon to say for sure whether Haumea really doesn't match up to this criteria.

Astronomers have discovered that Haumea, an egg-shaped dwarf planet at the edge of the Solar System, is surrounded by a ring of particles. Now, after finding a ring around Haumea, rings should not come as a surprise anymore. But as for how it formed, we don't yet know. Ortiz estimates that about a quarter of bodies in the outer solar system might have rings around them, although he stresses that this is still "pure speculation" for now.

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