Category Archives: Uranus
Voyager 2 may have been the second of NASA’s famous twin exploration spacecraft but it launched first, on August 20, 1977. Eight and a half years later it became the first (and last) spacecraft to visit Uranus, at 31,500 miles across the third largest planet in the Solar System. Voyager 2 made its closest pass by Uranus 31 years ago, giving us our best views to this day of the enormous ice giant and its moons.
The distant ice giant Uranus may not have been visited by a spacecraft since Voyager 2’s “Grand Tour” flyby in 1986 but the data gathered then is still being used today to make new discoveries. Most recently, researchers think they have found evidence of two previously unknown moons around Uranus, potentially bringing the planet’s count up to 29.
Out in the depths of our solar system, about 1.8 billion miles away from the Sun somewhere between the planets Saturn and far-flung Neptune, orbits the oddball ice giant Uranus – a frigid, thinly-ringed world tipped almost completely on its side and shrouded in both mystery and pale blue-green clouds. Aside from the occasional bright storm clouds spotted along the planet’s mid-latitudes and the even rarer darker blue storms, Uranus’ atmosphere has proven to be remarkably featureless… especially around its high southern latitudes.
Now, astronomer Erich Karkoschka from the University of Arizona has used imagery from Voyager 2’s 1986 visit to Uranus to bring out some visible features in the planet’s skies by using pattern recognition software to map out even the most subtle differences, and then boosting the contrast to make them more apparent. What he’s found are atmospheric anomalies that hint at curious structures in the planet’s dense core far beneath.
Watch a very cool animation below showing the new details Karkoschka has teased out of 29-year-old Voyager 2 data:
Wrapped in an atmosphere tinted pale blue by high-altitude methane, Uranus has occasionally been observed to develop large storms in its frigid windy skies. NASA’s Voyager 2 saw a few small storm clouds spotting Uranus during its flyby in Jan. 1986, and more recently some large but short-lived storms were observed by Hubble and the W.M. Keck Observatory as the planet moved toward its equinox in 2007. Now, seven years after its equinox, swirling storms are once again blooming on Uranus — and Keck astronomers have caught them on camera (while preparing for terrestrial hurricanes to make landfall!)
Voyager 2 may have been the second of NASA’s twin exploration spacecraft but it launched first, 35 years ago today on August 20, 1977. 8 1/2 years later it became the first (and last!) spacecraft to visit the gas giant Uranus, the third largest planet in the Solar System.
This ghostly image was taken by a Chilean ground-based telescope in 2002. It shows the enigmatic gas giant Uranus in near-infrared light, 7 of its 27 known moons visible. (For a labeled version of this image noting the moons, click here.)
Seventh planet from the sun, Uranus’ year is 84 Earth-years long. Like the other gas giants, Uranus has rings – thirteen, at last count. What makes Uranus especially different among the planets is its unique axial tilt…the entire planet, rings and all, is tipped nearly horizontal along its orbital plane. It’s as if it were “lying down”.
More recently on August 17, 2007 the Hubble Space Telescope captured a photo of Uranus with its rings angled edge-on to Earth. This viewpoint is only possible once every 42 years.
Uranus is approximately 4 times larger than Earth in diameter.
Image: European Southern Observatory