Artistic concept of Haumea and its ring system with
correct proportions for the main body and the ring. The ring is
located at a distance of 2287 km with respect to the center of
the ellipsoidal main body and it is darker than the surface of
Haumea. It was discovered by means of multiple telescopic
observations of a stellar occultation in Europe on January
21st, 2017. This and other findings on Haumea are reported in a
Nature paper by Ortiz et al. (2017) entitled “The size, shape,
density and ring of the dwarf planet Haumea from a stellar
occultation”. Credit: IAA-CSIC/UHU
Move over Saturn! 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.
The planet, dubbed Haumea, orbits the Sun far beyond
Neptune—the eighth and furthest recognised “full” planet in our
star system since Pluto was downgraded to dwarf status in 2006.
About eight billion kilometres (five billion miles) from the
Sun, Haumea spins rapidly on its own axis, and has a flattened,
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,” study
co-author Bruno Sicardy of the Paris Observatory told AFP.
The findings were published Wednesday in the journal
A ring system had previously been discovered around a centaur
dubbed Chariklo. Centaurs, which have unstable orbits, are
considered large comets, not planets, which means this is the first
observation of a ring around a dwarf planet.
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.
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.
In Haumea’s case, they found it sported a dense, Saturn-like
ring some 70 kilometres wide, made of frozen particles.
The planet has two moons.
of Uranus suggests some of its moons are on a collision
More information: The size, shape, density and ring of
the dwarf planet Haumea from a stellar occultation,
Nature (2017). nature.com/articles/doi:10.1038/nature24051
Journal reference: Nature
© 2017 AFP