This diagram shows the shape and size of the orbit of Comet Wild 2. The comet's orbit is shown in aqua. The orbits of Jupiter, Mars, and Earth are also shown.
Click on image for full size
Comet Wild 2
Comet Wild 2 is a short-period comet that
orbits the Sun once
every 6.39 years. A Swiss astronomer
named Paul Wild discovered it on January 6, 1978. Wild 2 is
pronounced "Vilt 2". The comet comes about
Sun as the planet Mars, and loops about
as far away as the planet Jupiter.
The comet's nucleus is about 5 km (3 miles) across, so Wild 2 is not an especially large comet.
Astronomers routinely calculate the positions of newly discovered comets
at earlier times to make sure someone hasn't re-discovered a previously
known comet. The scientists made a surprising discovery when they calculated
the orbit of Wild 2 backwards
to the years
that on September 10, 1974, the comet passed very close to Jupiter and
had its orbit substantially altered by that giant planet's gravity. Before
1974, Wild's orbit was in the outer solar system, ranging between Jupiter's
and Uranus' distance from the Sun.
So, until recently, Wild 2 had never come very close to the Sun.
Since Wild 2 has only taken a few swings
near the heat of the Sun, most
of its ices have not been melted away. Apparently Wild 2 has been kept
in cold storage since the early days of our Solar
System, which makes
it a very interesting comet to study. Studies of Wild 2 may help scientists
understand what the materials that originally formed our Solar System
Because Wild 2 (which is also known as Comet 81P/Wild 2) is in such a pristine condition, scientists chose it as the target of a space mission called Stardust. The Stardust spacecraft flew by Wild 2 in January 2004 and captured some tiny particles from the comet. It will return
those particles to Earth in 2006, giving scientists their first sample of cometary materials that may shed light on the history and evolution of our Solar System. Stardust also shot the best images ever taken of the nucleus of a comet during its flyby.
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