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A
comet slamming into Jupiter, blooming clouds on Uranus, monster
storms on Neptune, auroras on Jupiter and Saturn, wacky weather
on Mars - NASA's Hubble Space Telescope has kept its "eye"
on our solar system planets.
For
nearly a decade Hubble has monitored the weather on the red
planet, Mars. Hubble observations in the spring and summer
of 1997 provided detailed reports to help plan the landing
of NASA's Mars Pathfinder and the arrival of Mars Global Surveyor.
Pictures taken about a week before the landing of the Pathfinder
spacecraft show a dust storm churning through the deep canyons
of Valles Marineris, just 600 miles (1,000 kilometers) south
of the landing site.
Hubble
snapped an image on April 27, 1999 of an enormous cyclonic
storm system raking the northern polar regions of the Mars.
Nearly four times the size of the state of Texas, the storm
is composed of water ice clouds like storm systems on Earth,
rather than the dust typically found in Martian storms.
Hubble
observations of the turbulent clouds of Jupiter were used
to help target close-up picture-taking by the Jupiter-orbiting
Galileo probe.
In
1994 Hubble caught an invasion of Jupiter when 21 fragments
of comet Shoemaker-Levy 9 slammed into the planet. As each
comet fragment crashed into the giant planet, Hubble imaged
mushroom-shaped plumes along the edge of the planet. The largest
fragment impact created an Earth-sized "bull's-eye" pattern
on Jupiter.
Hubble's
sharp images show that the fragments, the largest of which
were probably a few miles across, did not break up catastrophically
before plunging into Jupiter's atmosphere. This reinforces
the notion that solid, massive bodies produced the comet's
atmospheric explosions.
Hubble
telescope observations were used to make global maps of Jupiter
for tracking changes in the dark debris caught up in the high-speed
winds at Jupiter's cloud tops. This debris is a natural tracer
of wind patterns and allows astronomers a better understanding
of the physics of the Jovian atmosphere.
Auroras,
curtains of light that seem to dance above the north and south
poles of Saturn and Jupiter, have also been studied by the
telescope. Astronomers used the Hubble's ultraviolet-light
camera, the imaging spectrograph, to probe these auroras.
Saturn's auroras rise more than 1,000 miles above the clouds.
These auroral displays are caused by an energetic "wind" of
charged particles from the Sun that sweeps over the planet,
much like Earth's aurora.
The
Hubble telescope has monitored weather and cloud patterns
on Uranus. An infrared view of the planet shows 20 clouds,
some circling the planet at more than 300 mph.
Astronomers
used Hubble telescope images, taken from 1994 to 1998, to
create a time-lapse movie that shows for the first time seasonal
changes on the planet. Once considered one of the blander-looking
planets, Uranus is now revealed as a dynamic world with the
brightest clouds in the outer solar system and possessing
a fragile ring system that wobbles like an unbalanced wagon
wheel. The clouds are probably composed of methane crystals,
which condense as warm bubbles of gas well up from deep in
the atmosphere of Uranus. The movie clearly shows for the
first time the wobble in the ring system, which is made up
of billions of tiny pebbles. This wobble may be caused by
Uranus's shape, which is like a slightly flattened globe,
along with the gravitational tug from its many moons.
Uranus
is tilted completely over on its side, giving rise to extreme
20-year-long seasons and unusual weather. For nearly a quarter
of the Uranian year, the Sun shines directly over each pole,
leaving the other half of the planet plunged into a long,
dark, frigid winter. The Northern Hemisphere of Uranus is
just now coming out of the grip of its decades-long winter.
As the sunlight reaches some latitudes, it warms the atmosphere.
Neptune's
unusual weather patterns also were the subject of a time-lapse
rotation movie. Using Hubble telescope pictures, the movie
shows that the planet has some of the wildest, weirdest weather
in the solar system. The telescope captured the most insightful
images to date of a planet whose blustery weather monster
storms and equatorial winds of 900 mph bewilder scientists.
Even
the outermost planet in our solar system hasn't escaped the
telescope's scrutiny. The Hubble telescope unveiled the never-before-seen
surface of Pluto, which orbits at the dim outer reaches of
the solar system nearly 3 billion miles (5 billion kilometers)
from the Sun. Pluto is two-thirds the size of the Earth's
moon but is 12,000 times farther away. Viewing surface detail
is as difficult as trying to read the printing on a golf ball
located 30 miles away! The Hubble's Faint Object Camera (FOC)
imaged nearly the entire surface of Pluto as it rotated through
its 6.4-day period in late June and early July 1994. The images,
made in blue light, show that Pluto is an unusually complex
object, with more large-scale contrast than any planet except
Earth.
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