|
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.
|
