Fw: NUFOIA: Spring Storms Rouse Uranus From Winter Hibernation
Subject: NUFOIA: Spring Storms Rouse Uranus From Winter Hibernation
Date: vrijdag, 2. april 1999 8:22
Source: National Aeronautics And Space Administration
Huge Spring Storms Rouse Uranus From Winter Hibernation
If springtime on Earth were anything like it will be on Uranus, we would be
experiencing waves of massive storms, each one covering the country from
Kansas to New York, with temperatures of 300 degrees below zero.
A dramatic new time-lapse movie by NASA's Hubble Space Telescope 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 a fragile ring system that
wobbles like an unbalanced wagon wheel. The clouds are probably made of
crystals of methane, which condense as warm bubbles of gas well up from
in the atmosphere of Uranus.
The movie, created by Hubble researcher Erich Karkoschka of the University
Arizona, clearly shows for the first time the wobble in the ring system,
which is made of billions of tiny pebbles. This wobble may be caused by
Uranus' shape, which is like a slightly flattened globe, along with the
gravitational tug from its many moons.
Although Uranus has been observed for more than 200 years, "no one has ever
seen this view in the modern era of astronomy because of the long year of
Uranus -- more than 84 Earth years," said Dr. Heidi Hammel, Massachusetts
Institute of Technology.
The seasonal changes on Earth are caused by our planet's rotational pole
being slightly tilted. Consequently, the Earth's Southern and Northern
hemispheres are alternately tipped toward or away from the Sun as the Earth
moves around its orbit. Uranus is tilted completely over on its side,
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,
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. This appears to be causing the atmosphere to come out of a
hibernation and stir back to life. Uranus does not have a solid surface,
is instead a ball of mostly hydrogen and helium. Absorption of red light by
methane in the atmosphere gives the planet its cyan color.
Uranus was discovered March 13, 1781, by William Herschel. Early visual
observers reported Jupiter-like cloud belts on the planet, but when NASA's
Voyager 2 flew by in 1986, Uranus appeared as featureless as a cue ball. In
the past 13 years, the planet has moved far enough along its orbit for the
sun to shine at mid- latitudes in the Northern Hemisphere. By the year
the sun will be shining directly over Uranus' equator.
Karkoschka, Hammel and other investigators used Hubble from 1994 through
to take images of Uranus in both visible and near-infrared light.
The Space Telescope Science Institute is operated by the Association of
Universities for Research in Astronomy, Inc. for NASA, under contract with
NASA's Goddard Space Flight Center, Greenbelt, MD. The Hubble Space
is a project of international cooperation between NASA and the European
- end -
NOTE TO EDITORS: The Uranus movie will air on NASA Television, Monday March
29 during the noon video file. NASA Television is broadcast on the GE2
satellite located on transponder 9C, at 85 degrees West longitude,
3880.0 MHz, audio 6.8 MHz. The movie is also available on the Internet at:
Editor's Note: The original news release can be found at
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