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Artist's impression of the unique object C/2014 S3 (PANSTARRS). Observations with ESO’s Very Large Telescope, and the Canada France Hawai`i Telescope, show that this is the first object to be discovered that is on a long-period cometary orbit, but that has the characteristics of a pristine inner Solar System asteroid. It may provide important clues about how the Solar System formed. Source: ESO/M. KornmesserBeyond the asteroid belt, beyond the reaches of Neptune, the Oort Cloud orbits, its myriad icy bodies floating in interstellar space. First proposed by Dutch astronomer Jan Oort in 1950, the Oort Cloud is purely theoretical. If it does exist, NASA estimates the Voyager 1 won’t reach it for another 300 years. But every now and then, scientists spot an icy body they believe hailed from the region.

C/2014 S3 is one of those bodies.

Last week, Karen Meech, of the University of Hawaii’s Institute for Astronomy, and colleagues published a paper in Science Advances proposing that C/2014 S3 formed in the inner solar system around the same time as Earth, but was then expelled to the Oort Cloud, where it was preserved in freezing temperatures for billions of years.

Discovered on Sept. 22, 2014 by the Pan-STARRS1 telescope, C/2014 S3 was described as a “weakly active comet at a heliocentric distance of 2.1 AU (astronomical units).” Meech and colleagues followed the initial examination with observations from the European Southern Observatory (ESO)’s Very Large Telescope and the Canada France Hawaii Telescope.

“Its current long orbital period (around 860 years) suggests that its source is in the Oort Cloud, and it was nudged comparatively recently into an orbit that brings it closer to the sun,” according to the ESO.

The researchers have taken to calling C/2014 S3 a “Manx” comet, after the tailless cat, due to its lack of a tail when it passes close to the sun.

The researchers noted C/2014 S3’s physical similarity to an inner main belt S-type asteroid.

“It does not look like a typical comet, which are believed to form in the outer solar system and are icy, rather than rocky,” according to the ESO. Also, “the very weak comet-like activity associated with C/2014 S3, which is consistent with the sublimation of water ice, is about a million times lower than active long-period comets at a similar distance from the sun.”

According to the researchers, various theoretical models predict different ratios of rocky and icy material in the Oort Cloud. However, objects like C/2014 S3 can help scientists distinguish which models are more accurate. To choose the proper models, the researchers estimate that between 50 and 100 Manx objects need characterization.

“Depending on how many we find, we will know whether the giant planets danced across the solar system when they were young, or if they grew up quietly without moving much,” said coauthor Olivier Hainaut in a statement. 

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