New "Minor Planet" Found in Solar System

Brian Handwerk
for National Geographic News
August 19, 2008

The solar system as we know it is a bit more crowded due to the recent discovery of an intriguing new "minor planet."

The object, dubbed 2006 SQ372, is a kind of tailless comet that's currently some two billion miles (three billion kilometers) from Earth, a bit closer to the sun than Neptune.

But the lump of ice and rock is moving on a long, elliptical orbit that will take it on a round-trip journey lasting about 22,500 years.

At its peak distance, the body will be about 150 billion miles (241 billion kilometers) from Earth—1,600 times farther than the distance between Earth and the sun.

Visitor From the Oort Cloud?

Scientists first sighted the unusual object in 2006 while scanning the skies for distant supernovae that help measure the ongoing expansion of the universe.

Based on data collected between 2005 and 2007, Andrew Becker of the University of Washington and colleagues charted the object's unusual orbit—an ellipse four times as long as it is wide.

The object appears to be a comet that does not get close enough to the sun for its ice to evaporate and form a tail.

"Currently it's in a transient orbit right now, an unstable orbit," Becker said.

"It's close to the orbits of Uranus and Neptune, and we think that in a couple of hundred million years, one of those planets will scatter it."

Becker's team believes 2006 SQ372 probably came from the inner edges of the Oort cloud, a theoretical region of asteroid-like bodies several trillion miles away that is believed to be the source of many known comets.

The scientists think the body was bounced into the Oort cloud from the inner solar system during planet formation some 4.5 billion years ago.

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