The pair of space rock rings encircle the asteroid Chariklo. They were most likely formed after a collision scattered debris around the asteroid, according to a new study unveiled today (March 27). The asteroid rings also suggests the presence of a still-undiscovered moon around Chariklo that's keeping them stable, researchers said.
"We weren’t looking for a ring and didn’t think small bodies like Chariklo had them at all, so the discovery — and the amazing amount of detail we saw in the system — came as a complete surprise!" study leader Felipe Braga-Ribas, of the National Observatory in Brazil said in a statement today. [Asteroid with Rings: Artist Views of Space Rock Chariklo (Photos)]
An artist's view of the rings surrounding the asteroid Chariklo, which is only 155 miles (250 kilometers) across. The asteroid is the first non-planetary body in the solar system discovered to have its own ring system. Image released March 26, 2014.
Credit: Lucie Maquet
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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 Strangest Asteroids in the Solar System]
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 inSaturn's rings.