Most distant Solar System object detected
BBC News Online - Science Editor Dr David Whitehouse
9th Nov 1999
Astronomers have observed an object orbiting the Sun that is more distant
than anything yet discovered. It has been designated 1999 DG8. It is
an example of what researchers call a Scattered Kuiper Belt Object (SKBO).
It is probably about 100 kilometres in size and made of ice and rock.
It is believed to a leftover from the formation of the planets some
four and a half billion years ago.
Since the first Kuiper Belt Object (KBO) was discovered in 1992, astronomers
have found over 100 such objects that orbit the Sun beyond the most
There could be over a hundred thousand of them whose mass in total would
equal about 10% of the Earth's mass.
KBO's have been found in three types of orbit. Main belt KBO's, KBO's
in a so-called resonant orbit with the planet Neptune, and SKBO's that
have been flung into deep space after a gravitational encounter with
Neptune. A mission to the Kuiper Belt is being planned.
1999 DG8 was found by a team led by Dr Brett Gladman of the Canadian
Institute of Theoretical Physics. He is currently working at the Observatorie
de la Cote d'Azur in France.
It is the most distant solar system object ever photographed, being
60 times further away from the Sun than the Earth.
Because it was only seen on two consecutive nights earlier this year,
astronomers do not have enough measurements to calculate an orbit for
it. This means that researchers do not know how much further out it
will go. Accurate orbits
More SKO's were detected earlier this year. Chadwick Trujillo and David
Jewitt of the Institute of Astronomy in Hawaii and Jane Luu of the Leiden
Observatory in the Netherlands are about to report the discovery of
three more. Each one was tracked for three months allowing fairly accurate
orbits to be calculated.
One of them, designated 1999 CF119, has the largest known orbit of anything
orbiting the Sun. Its furthest point from the Sun is 200 times the Earth-Sun
distance, which is known as an Astronomical Unit (AU).
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