Astronomers used seven telescopes, but just one revealed the pair of
rings orbiting the rocky Chariklo. The asteroid's 155-mile diameter (250
kilometers) is dwarfed by the giant gas planets, the only other bodies
known to have rings.
"This discovery shows that size is not important in order to have — or
not have — rings," Felipe Braga-Ribas, of the National Observatory in
Brazil, told Space.com by email.
An asteroid among giants
On June 3, 2013, Braga-Ribas led a team of astronomers in observing
Chariklo as it passed in front of a distant star — a process known as an
occultation. As the asteroid traveled, it blocked light from the star,
enabling scientists to learn more about it.
The astronomers were surprised to discover that a few seconds before
and after the main occultation, the light dimmed slightly, indicating
that something circled the rocky asteroid. By comparing the data
gathered from seven different telescopes, the team was able to identify
the shape, size and orientation of the rings.
The system consists of a dense, 4-mile-wide (7 km) ring near the planet, and a smaller 2-mile-wide (3 km) ring farther out.
From the surface of the asteroid,
"they would be two spectacular sharp and really bright rings, crossing
all the sky," Braga-Ribas said. "They would be noticeably close, as they
are at about 1/1,000 of the moon's distance from us," he added.
He went on to say that the larger, inner ring would block the view of
the outer ring from the ground. The rings are similar to those around
Saturn, in that both are very dense, bright and possibly formed by rock
and water ice. But their scales are quite different.
"The whole Chariklo system would fit about 12 times in the Cassini
Division," Braga-Ribas said, referring to the largest gap in Saturn's rings.
Particles orbiting Chariklo also travel more slowly — only tens of
meters per second, compared with tens of kilometers per second in the rings of Saturn.
While Saturn is the most well-known ringed body in the solar system,
Jupiter, Neptune and Uranus also have their own, fainter rings.
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