National Aeronautics and Space Administration Logo
Follow this link to skip to the main content NASA Banner
Solar System Exploration
News & Events
Huge Spring Storms Rouse Uranus from Winter Hibernation
Huge Spring Storms Rouse Uranus from Winter Hibernation
29 Mar 1999
(Source: NASA Headquarters)

Donald Savage
Headquarters, Washington, DC
(Phone: 202/358-1727)

Nancy Neal
Goddard Space Flight Center, Greenbelt, MD
(Phone: 301/286-0039)

Ray Villard
Space Telescope Science Institute, Baltimore, MD
(Phone: 410/338-4514)

RELEASE: 99-47

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 deep in the atmosphere of Uranus.

The movie, created by Hubble researcher Erich Karkoschka of the University of 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, 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. This appears to be causing the atmosphere to come out of a frigid hibernation and stir back to life. Uranus does not have a solid surface, but 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 2007, the sun will be shining directly over Uranus' equator.

Karkoschka, Hammel and other investigators used Hubble from 1994 through 1998 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 Telescope is a project of international cooperation between NASA and the European Space Agency.

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, frequency 3880.0 MHz, audio 6.8 MHz. The movie is also available on the Internet at:

http://oposite.stsci.edu/pubinfo/latest.html
http://oposite.stsci.edu/pubinfo/pictures.html

News Archive Search  Go!
Show  results per page
 
 
Awards and Recognition   Solar System Exploration Roadmap   Contact Us   Site Map   Print This Page
NASA Official: Kristen Erickson
Advisory: Dr. James Green, Director of Planetary Science
Outreach Manager: Alice Wessen
Curator/Editor: Phil Davis
Science Writer: Autumn Burdick
Producer: Greg Baerg
Webmaster: David Martin
> NASA Science Mission Directorate
> Budgets, Strategic Plans and Accountability Reports
> Equal Employment Opportunity Data
   Posted Pursuant to the No Fear Act
> Information-Dissemination Policies and Inventories
> Freedom of Information Act
> Privacy Policy & Important Notices
> Inspector General Hotline
> Office of the Inspector General
> NASA Communications Policy
> USA.gov
> ExpectMore.gov
> NASA Advisory Council
> Open Government at NASA
Last Updated: 5 Jun 2001