Uranus

What Uranus Cloud Tops Have in Common With Rotten Eggs

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Uranus
Arriving at Uranus in 1986, Voyager 2 observed a bluish orb with extremely subtle features. A haze layer hid most of the planet’s cloud features from view. Credit: NASA/JPL-Caltech

  

Even after decades of observations and a visit by NASA’s Voyager 2 spacecraft, Uranus held on to one critical secret — the composition of its clouds. Now, one of the key components of the planet’s clouds has finally been verified. 

A global research team that includes Glenn Orton of NASA’s Jet Propulsion Laboratory in Pasadena, California, has spectroscopically dissected the infrared light from Uranus captured by the 26.25-foot (8-meter) Gemini North telescope on Hawaii’s Mauna Kea. They found hydrogen sulfide, the odiferous gas that most people avoid, in Uranus’ cloud tops. The long-sought evidence was published in the April 23rd issue of the journal Nature Astronomy.

The detection of hydrogen sulfide high in Uranus’ cloud deck (and presumably Neptune’s) is a striking difference from the gas giant planets located closer to the Sun — Jupiter and Saturn — where ammonia is observed above the clouds, but no hydrogen sulfide. These differences in atmospheric composition shed light on questions about the planets’ formation and history. 

 
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Uranus May Have Two Undiscovered Moons

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Written by Tara Roberts
University of Idaho Communications
For NASA Jet Propulsion Laboratory, Pasadena, California 
October 21, 2016 at 1:04 p.m. EDT

Uranus is seen in this false-color view from NASA’s Hubble Space Telescope from August 2003. The brightness of the planet’s faint rings and dark moons has been enhanced for visibility. Image credit: NASA/Erich Karkoschka (Univ. Arizona)

 

NASA’s Voyager 2 spacecraft flew by Uranus 30 years ago, but researchers are still making discoveries from the data it gathered then. A new study led by University of Idaho researchers suggests there could be two tiny, previously undiscovered moonlets orbiting near two of the planet’s rings.

Rob Chancia, a University of Idaho doctoral student, spotted key patterns in the rings while examining decades-old images of Uranus’ icy rings taken by Voyager 2 in 1986. He noticed the amount of ring material on the edge of the alpha ring — one of the brightest of Uranus’ multiple rings — varied periodically. A similar, even more promising pattern occurred in the same part of the neighboring beta ring.

“When you look at this pattern in different places around the ring, the wavelength is different — that points to something changing as you go around the ring. There’s something breaking the symmetry,” said Matt Hedman, an assistant professor of physics at the University of Idaho, who worked with Chancia to investigate the finding. 

Their results will be published in The Astronomical Journal and have been posted to the pre-press site arXiv.

 

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Voyager Mission Celebrates 30 Years Since Uranus

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This is an image of the planet Uranus taken by the spacecraft Voyager 2 in 1986. The Voyager project is managed for NASA by the Jet Propulsion Laboratory.

 

Humanity has visited Uranus only once, and that was 30 years ago. NASA’s Voyager 2 spacecraft got its closest look at the mysterious, distant, gaseous planet on Jan. 24, 1986.

Voyager 2 sent back stunning images of the planet and its moons during the flyby, which allowed for about 5.5 hours of close study. The spacecraft got within 50,600 miles (81,500 kilometers) of Uranus during that time.

“We knew Uranus would be different because it’s tipped on its side, and we expected surprises,” said Ed Stone, project scientist for the Voyager mission, based at the California Institute of Technology, Pasadena. Stone has served as project scientist since 1972, continuing in that role today.

Uranus revealed itself to be the coldest planet known in our solar system, even though it’s not the farthest from the sun. This is because it has no internal heat source.

Scientists determined that the atmosphere of Uranus is 85 percent hydrogen and 15 percent helium. There was also evidence of a boiling ocean about 500 miles (800 kilometers) below the cloud tops.

Scientists found that Uranus has a magnetic field different from any they had ever encountered previously. At Mercury, Earth, Jupiter and Saturn, the magnetic field is aligned approximately with the rotational axis.

“Then we got to Uranus and saw that the poles were closer to the equator,” Stone said. “Neptune turned out to be similar. The magnetic field was not quite centered with the center of the planet.”

This surface magnetic field of Uranus was also stronger than that of Saturn. Data from Voyager 2 helped scientists determine that the magnetic tail of Uranus twists into a helix stretching 6 million miles (10 million kilometers) in the direction pointed away from the sun. Understanding how planetary magnetic fields interact with the sun is a key part of NASA’s goal to understand the very nature of space. Not only does studying the sun-planet connection provide information useful for space travel, but it helps shed light on the origins of planets and their potential for harboring life.

Voyager 2 also discovered 10 new moons (there are 27 total) and two new rings at the planet, which also proved fascinating. An icy moon called Miranda revealed a peculiar, varied landscape and evidence of active geologic activity in the past. While only about 300 miles (500 kilometers) in diameter, this small object boasts giant canyons that could be up to 12 times as deep as the Grand Canyon in Arizona. Miranda also has three unique features called “coronae,” which are lightly cratered collections of ridges and valleys. Scientists think this moon could have been shattered and then reassembled.

Mission planners designed Voyager 2’s Uranus encounter so that the spacecraft would receive a gravity assist to help it reach Neptune. In 1989, Voyager 2 added Neptune to its resume of first-ever looks.

“The Uranus encounter was very exciting for me,” said Suzanne Dodd, project manager for Voyager, based at NASA’s Jet Propulsion Laboratory, Pasadena, California, who began her career with the mission while Voyager 2 was en route to Uranus.” It was my first planetary encounter and it was of a planet humanity had never seen up close before. Every new image showed more details of Uranus, and it had lots of surprises for the scientists. I hope another spacecraft will be sent to explore Uranus, to explore the planet in more detail, in my lifetime.”

Voyager 2 was launched on Aug. 20, 1977, 16 days before its twin, Voyager 1. In August 2012, Voyager 1 made history as the first spacecraft to enter interstellar space, crossing the boundary encompassing our solar system’s planets, sun and solar wind. Voyager 2 is also expected to reach interstellar space within the next several years.

The Voyagers were built by JPL, which continues to operate both spacecraft. JPL is a division of Caltech. For more information about the Voyager spacecraft, visit: http://www.nasa.gov/voyager and http://voyager.jpl.nasa.gov