Scientists have found a ring around an unassuming mini-planet in our Solar System to debunk the theory that only giant planets can be so adorned. This is the first observation of a ring around a dwarf planet.
The planet, dubbed Haumea, orbits the Sun far beyond Neptune – the eighth and furthest recognized "full" planet in our star system since Pluto was downgraded to dwarf status in 2006.
About eight billion kilometers from the Sun, Haumea spins rapidly on its own axis, and has a flattened, cigar-like shape. It takes 285 years to circle the Sun.
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.
"Our discovery proves that there is a lot more diversity and imagination in our solar system than we had thought," said study co-author Bruno Sicardy of the Paris Observatory.
A ring system had previously been discovered around a centaur dubbed Chariklo. Centaurs, which have unstable orbits, are considered large comets, not planets.
The new discovery came when Sicardy and a team predicted that Haumea would cross in front of a specific star, from Earth's perspective, on January 21 this year.
They trained 12 telescopes at 10 different laboratories on the spot and were able to measure many of the physical characteristics of the little-known planet discovered in 2004.
Concept picture of Haumea and its rings.
By using the data collected from telescopes, the astronomers determined that the ring was about 70 kilometers wide, which is with a radius of nearly 2,414 kilometers.
Besides, scientists can infer much about a planet's density and size by how much light it blocks out, as it moves in front of a star.
As for how the ring has formed, however, the astronomers are still not sure yet. In fact, many of the mechanisms thought to have formed rings around giant planets couldn’t explain the rings around Haumea and Chariklo.
The findings were published Wednesday in the journal Nature.
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