The Kuiper (pronounced Ki-Per) Belt is often called our solar system's 'final
frontier.' This disk-shaped region of icy debris is about 12 to 15 billion
kilometers (7.5 billion to 9.3 billion miles) from our Sun
. Its existence confirmed only a decade ago, the Kuiper
Belt and its collection of icy objects - KBOs - are an emerging area of research
in planetary science.
The most recent exciting discovery to come out of the Kuiper Belt is "Quaoar
(Kwa-whar), officially known as 2002 LM60, a frozen world orbiting our sun about
a billion miles beyond the orbit of Pluto
The tiny world's diameter is 1,300 km (800 miles) - about half the size of
Pluto. It is the largest of the more than 500 Kuiper Belt Objects discovered
in the last decade. Quaoar/2002 LM60 orbits our Sun in a near circle, more
so than any of the other planets or bodies in our solar system.
Quaoar is still an unofficial name. The two scientists who discovered 2002 LM60 have asked the
International Astronomical Union to name the tiny world "Quaoar" in honor of a
Native American creation god.
KBOs like Quaoar are tough to spot. The tiny objects are billions of kilometers from
Earth and very difficult to pinpoint with ground-based telescopes. Even the powerful
cameras of NASA's Hubble Space Telescope
can only produce rough images. No
spacecraft have visited this distant region, though NASA's proposed New
spacecraft could fly through in 2026.
The Search for the Kuiper Belt
In 1950, Dutch astronomer Jan Oort hypothesized that comets came from a
vast shell of icy bodies about 50,000 times farther from the Sun than the
. A year later astronomer Gerard Kuiper suggested that some
comet-like debris from the formation of the solar system should also be
just beyond Neptune
. In fact, he argued, it would be unusual not to
find such a continuum of particles since this would imply the
primordial solar system has a discrete "edge."
This notion was reinforced by the realization that there is a separate
population of comets
, called the Jupiter family, that behave strikingly
different than those coming from the far reaches of the Oort cloud.
Besides orbiting the Sun in less than 20 years (as opposed to 200
million years for an Oort member), the comets are unique because their
orbits lie near the plane of the Earth's orbit around the Sun. In
addition, all these comets go around the Sun in the same direction as
Kuiper's hypothesis was reinforced in the early 1980s when computer
simulations of the solar system's formation predicted that a disk of
debris should naturally form around the edge of the solar system.
According to this scenario, planets would have agglomerated quickly in
the inner region of the Sun's primordial circumstellar disk, and
gravitationally swept up residual debris. However, beyond Neptune, the
last of the gas giants, there should be a debris-field of icy objects
that never coalesced to form planets.
The Kuiper belt remained theory until the 1992 detection of a 150-mile
wide body, called 1992QB1 at the distance of the suspected belt.
Several similar-sized objects were discovered quickly confirming the
Kuiper belt was real. The planet Pluto, discovered in 1930, is
considered the largest member of this Kuiper belt region. Also,
Neptune's satellites, Triton and Nereid, and Saturn's satellite, Phoebe
are in unusual orbits and may be captured Kuiper belt objects.