Astronomers have discovered that Haumea, an egg-shaped dwarf planet at the edge of the Solar System, is surrounded by a ring of particles. Haumea is one of the five recognized dwarf planets in the Solar System, and now also the only one to have a ring.
Haumea Is The Only Dwarf Planet With A Ring
This recent discovery implies that there might be more small bodies in the outer Solar System surrounded by rings, and humans simply haven't been able to determine every single one of them yet. Such a task is probably impossible since space is so vast.
The researchers revealed that Haumea is surrounded by a ring of material that's roughly 43 miles in width. This marks the third instance in the last few years were a ring was discovered around an object that's technically not a planet.
As the researchers suggest in their new work, published Wednesday, Oct. 11, in the journal Nature, ring systems in the outer Solar System are not uncommon. The team, made up of international astronomers, watched the dwarf planet briefly pass in front of a star, which blocked out that star's light. This kind of passing is observed by astronomers to look at the foreground object, determine its size and shape, and figure whether or not it has rings.
Haumea Occultation: The Discovery
On Jan. 21, the astronomy team observed Haumea via 12 telescopes scattered across Europe. It passed a distant star, which caused a momentary eclipse called an occultation. As a result, the team was able to pick up certain things about the dwarf planet, including the possibility of having a ring.
Haumea's ring has a radius of nearly 1,500 miles, the team discovered, and it moves very slowly in contrast with its host planet. By the time its ring is able to complete one revolution, Haumea will have already spun around its axis thrice.
Why Does Haumea Have A Ring?
Why is there a ring there in the first place, though? Unfortunately, the astronomers have no clue, because the way rings form around giant planets don't seem to mirror how a ring formed around Haumea. Saturn's rings, for example partly came from Enceladus, one of its 53 moons. Haumea, by contrast, has a couple of moons, but they're far too small and distant to have contributed to the ring, according to Amanda Sickafoose, an MIT planetary astronomer who wrote a Nature entry on Haumea's ring.
"I think that where the rings are coming from, how they're forming essentially, is going to be a big topic of research."