[FoRK] Update to yesterday's Kuiper Belt news

Joseph S. Barrera III joe at barrera.org
Wed Feb 25 18:05:33 PST 2004

Something found this week in the Kuiper belt
bigger than Pennsylvania, let alone Philidelpha...

- Joe


Date Released: Friday, February 20, 2004
Source: California Institute of Technology

Planetary scientists find planetoid in Kuiper Belt; could be biggest yet

Planetary scientists at the California Institute of Technology and Yale
University on Tuesday night discovered a new planetoid in the outer
fringes of the solar system.

The planetoid, currently known only as 2004 DW, could be even larger
than Quaoar--the current record holder in the area known as the Kuiper
Belt--and is some 4.4 billion miles from Earth.

According to the discoverers, Caltech associate professor of planetary
astronomy Mike Brown and his colleagues Chad Trujillo (now at the Gemini
North observatory in Hawaii), and David Rabinowitz of Yale University,
the planetoid was found as part of the same search program that
discovered Quaoar in late 2002. The astronomers use the 48-inch Samuel
Oschin Telescope at Palomar Observatory and the recently installed QUEST
CCD camera built by a consortium including Yale and the University of
Indiana, to systematically study different regions of the sky each night.

Unlike Quaoar, the new planetoid hasn't yet been pinpointed on old
photographic plates or other images. Because its orbit is therefore not
well understood yet, it cannot be given an official name.

"So far we only have a one-day orbit," said Brown, explaining that the
data covers only a tiny fraction of the orbit the object follows in its
more than 300-year trip around the sun. "From that we know only how far
away it is and how its orbit is tilted relative to the planets."

The tilt that Brown has measured is an astonishingly large 20 degrees,
larger even than that of Pluto, which has an orbital inclination of 17
degrees and is an anomaly among the otherwise planar planets.

The size of 2004 DW is not yet certain; Brown estimates a size of about
1,400 kilometers, based on a comparison of the planetoid's luminosity
with that of Quaoar. Because the distance of the object can already be
calculated, its luminosity should be a good indicator of its size
relative to Quaoar, provided the two objects have the same albedo, or

Quaoar is known to have an albedo of about 10 percent, which is slightly
higher than the reflectivity of our own moon. Thus, if the new object is
similar, the 1,400-kilometer estimate should hold. If its albedo is
lower, then it could actually be somewhat larger; or if higher, smaller.

According to Brown, scientists know little about the albedos of objects
this large this far away, so the true size is quite uncertain.
Researchers could best make size measurements with the Hubble Space
Telescope or the newer Spitzer Space Telescope.

The continued discovery of massive planetoids on the outer fringe of the
solar system is further evidence that objects even farther and even
larger are lurking out there. "It's now only a matter of time before
something is going to be discovered out there that will change our
entire view of the outer solar system," Brown says.

The team is working hard to uncover new information about the planetoid,
which they will release as it becomes available, Brown adds. Other
telescopes will also be used to better characterize the planetoid's

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