Astronomers announced yesterday the discovery of the furthest known object in our solar system -- a finding that may change our thinking about the history of the solar system and start a naming war with Canadian connections.
A group of NASA scientists, led by California Institute of Technology astronomer Michael Brown, found the object in November. It is now about 16 billion kilometres from the sun and at the furthest extent of its orbit will travel out 130 billion kilometres -- about 900 times the Earth's distance from the sun.
It is between 1,300 and 1,600 kilometres in diameter, which would make it smaller than Pluto. The object's colour and gleam are also quite striking and quite mysterious. "We didn't expect anything else out here to be both red and shiny and that is one of the mysteries we are currently trying to understand about the object," Prof. Brown told a press conference in Los Angeles.
The U.S. scientists believe the object, whose composition is unclear, may be the first of what have been hypothesized as Oort Cloud bodies. These are objects that were almost ejected entirely from the solar system by the gravitational "kick" of the large outer planets like Neptune. But then, it is believed, the combined effect of the gravitational field of nearby stars altered the paths of these objects. They eventually settled into an orbit of the sun at an average distance of 44,000 times the Earth's distance from the sun.
However, because the new body is closer to the sun than Oort objects are supposed to be, an alternative theory suggests they were kicked into their orbits by planets which have since been expelled from the solar system. "When we get an orbital distribution of a number of these objects we will have an imprint of this process," said University of British Columbia astronomer Brett Gladman.
While its odd coloration and strange orbit excites scientists, its naming may be of special interest to Canadians. The object U.S. astronomers are calling a planetoid -- a planet-like object but not considered big enough to be a true planet -- has provisionally been dubbed Sedna.
Sedna is the Inuit goddess of the sea who, according to one version of the story, was originally a woman thrown into icy Arctic waters by her father. He was attempting to appease another god who had tricked Sedna into marrying him and from whom she was fleeing. When she tried to get back into the boat, her father beat her frozen hands, which when they broke off, turned into whales and other large mammals. While she sank, she did not die but became the goddess of the sea.
The planetoid's cold temperature, -200 degrees, and great distance from the sun led the U.S. scientists to think about names from the mythology of the Inuit who inhabit Canada's far north and other Arctic regions.
"We knew it could end up being the coldest, most distant object in the entire solar system. And early one day we decided it was appropriate to name any objects out of this region after Arctic mythology," Prof. Brown said. After some research into myths, the astronomers decided Sedna was the most appropriate name to give what the scientists believe may be the first a host of other objects in the same region.
However, the International Astronomical Union, which governs the naming of astronomical objects, isn't so sure Sedna will fly.
Brian Marsden, the Harvard University astronomer who is secretary of the 15-member naming board, said it is a definite violation of protocol to announce a name and assume it is going to be accepted.
"I don't know how well this name will fly with IAU. Other members of committee might vote against it because the name was brought forward in this manner. It should go through the IAU rather than be announced in the newspaper. That is not the proper way to do this, and it is a possibility that they say no."
He pointed out that while the names of creation gods are reserved for certain classes of astronomical bodies, this new object's orbit and location is so unique that his organization might have to start a whole new naming protocol for it and its fellows. For now, its only proper name is a number, 2003 VB12.
U.S. astronomers say they have found the most distant object in the solar system at 16 billion kilometres away. This new planet-like object has been provisionally called Sedna.
Earth (12,900 km in diameter)
Moon (3,380 km in diameter)
Pluto (2,250 km in diameter)
Sedna (1,290-1,600 km in diameter)
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