Astronomers thrilled by extreme storms on Uranus

These are infrared images of Uranus (1.6 and 2.2 microns) obtained on Aug. 6, 2014, with adaptive optics on the 10-meter Keck telescope. 

The white spot is an extremely large storm that was brighter than any feature ever recorded on the planet in the 2.2 micron band. 

The cloud rotating into view at the lower-right limb grew into the large storm that was seen by amateur astronomers at visible wavelengths. 

Credit: Imke de Pater (UC Berkeley) & Keck Observatory images.

The normally bland face of Uranus has become increasingly stormy, with enormous cloud systems so bright that for the first time ever, amateur astronomers are able to see details in the planet's hazy blue-green atmosphere.

Imke de Pater

"The weather on Uranus is incredibly active," said Imke de Pater, professor and chair of astronomy at the University of California, Berkeley, and leader of the team that first noticed the activity when observing the planet with adaptive optics on the W. M. Keck II Telescope in Hawaii.

"This type of activity would have been expected in 2007, when Uranus's once every 42-year equinox occurred and the sun shined directly on the equator," noted co-investigator Heidi Hammel of the Association of Universities for Research in Astronomy.

"But we predicted that such activity would have died down by now. Why we see these incredible storms now is beyond anybody's guess."

Heidi Hammel

In all, de Pater, Hammel and their team detected eight large storms on Uranus's northern hemisphere when observing the planet with the Keck Telescope on August 5 and 6.

One was the brightest storm ever seen on Uranus at 2.2 microns, a wavelength that senses clouds just below the tropopause, where the pressure ranges from about 300 to 500 mbar, or half the pressure at Earth's surface.

The storm accounted for 30 percent of all light reflected by the rest of the planet at this wavelength.

When amateur astronomers heard about the activity, they turned their telescopes on the planet and were amazed to see a bright blotch on the surface of a normally boring blue dot.

'I got it!'

French amateur astronomer Marc Delcroix processed the amateur images and confirmed the discovery of a bright spot on an image by French amateur Régis De-Bénedictis, then in others taken by fellow amateurs in September and October.

He had his own chance on Oct. 3 and 4 to photograph it with the Pic du Midi one-meter telescope, where on the second night, "I caught the feature when it was transiting, and I thought, 'Yes, I got it!'" said Delcroix.

"I was thrilled to see such activity on Uranus. Getting details on Mars, Jupiter or Saturn is now routine, but seeing details on Uranus and Neptune are the new frontiers for us amateurs and I did not want to miss that," said Delcroix, who works for an auto parts supplier in Toulouse and has been observing the skies, Jupiter in particular, with his backyard telescope since 2006 and, since 2012, occasionally with the Pic du Midi telescope.

"I was so happy to confirm myself these first amateur images on this bright storm on Uranus, feeling I was living a very special moment for planetary amateur astronomy."

These are optical images of Uranus on Sept. 19 and Oct. 2, showing the dramatic appearance of a bright storm on a planet that normally displays only a diffuse bright polar region. 

Credit: Photo by Anthony Wesley, Murrumbateman, Australia.

Interestingly, the extremely bright storm seen by Keck in the near infrared is not the one seen by the amateurs, which is much deeper in the atmosphere than the one that initially caused all the excitement. De Pater's colleague Larry Sromovsky, a planetary scientist at the University of Wisconsin, Madison, identified the amateur spot as one of the few features on the Keck images from August 5 that was only seen at 1.6 microns, and not at 2.2 microns.

The 1.6 micron light is emitted from deeper in the atmosphere, which means that this feature is below the uppermost cloud layer of methane-ice in Uranus's atmosphere.

"The colours and morphology of this cloud complex suggests that the storm may be tied to a vortex in the deeper atmosphere similar to two large cloud complexes seen during the equinox," Sromovsky said.

Such vortices could be anchored much deeper in the atmosphere and extend over large vertical distances, as inferred from similar vortices on Jupiter, including its Great Red Spot.

An expanded team of astronomers led by Kunio M. Sayanagi, an Assistant Professor at Hampton University in Virginia, leveraged the amateur observations to activate a "Target of Opportunity" proposal on the Hubble Space Telescope, which imaged the entire planet on Oct. 14.

Observing at a variety of wavelengths, HST revealed multiple storm components extending over a distance of more than 9,000 kilometers (5,760 miles) and clouds at a variety of altitudes.

De Pater, Sromovsky, Hammel and Pat Fry of the University of Wisconsin will report the details of their observations on Nov. 12 at a meeting of the American Astronomical Society's Division of Planetary Sciences in Tucson, Ariz.

Ice giant

This is an animation showing the movement of the bright spot as Uranus rotated over a two hour period on Oct. 4, 2014. 

The infrared images were taken at the Pic du Midi telescope in the French Pyrénées. 

Credit: Marc Delcroix and F. Colas (S2P).

Uranus is an ice giant, about four times the diameter of Earth, with an atmosphere of hydrogen and helium, with just a bit of methane to give it a blue tint.

Because it is so distant, 30 times farther from the sun than Earth, astronomers were able to see little detail on its surface until adaptive optics on the Keck telescopes revealed features much like those on Jupiter.

De Pater and her colleagues have been following Uranus for more than a decade, charting the weather on the planet, including bands of circulating clouds, massive swirling storms and convective features at its north pole.

Bright clouds are probably caused by gases such as methane rising in the atmosphere and condensing into highly reflective clouds of methane ice.

Because Uranus has no internal source of heat, its atmospheric activity was thought to be driven solely by sunlight, which is now weak in the northern hemisphere. Hence astronomers were surprised when these observations showed such intense activity.

Observations taken with the Keck telescope by Christoph Baranec, an Assistant Professor at the University of Hawaii on Manoa, revealed that the storm was still active, but had a different morphology and possibly reduced intensity.

"If indeed these features are high-altitude clouds generated by flow perturbations associated with a deeper vortex system, such drastic fluctuations in intensity would indeed be possible," Sromovsky added.

"These unexpected observations remind us keenly of how little we understand about atmospheric dynamics in outer planet atmospheres," the authors wrote in their paper.

Uranus's Moon Miranda: Bizarre Shape Explained

Uranus' icy moon Miranda is seen in this image from NASA's Voyager 2 probe on Jan. 24, 1986.

Credit: NASA/JPL-Caltech

The strange appearance of Uranus' moon Miranda may finally have an explanation.

Miranda resembles Frankenstein's monster, a bizarre jumble of parts that didn't quite merge properly.

Now, researchers suggest they may know why Miranda looks so odd: Constant squeezing and stretching from Uranus caused the moon's insides to heat up and churn.

Miranda is the innermost of Uranus' five major moons.

Though Miranda is only 293 miles (471 kilometers) wide, about one-seventh as large as Earth's moon, this ball of ice and rock possesses one of the oddest and most varied landscapes known among extraterrestrial bodies, including giant canyons up to 12 times deeper than the Grand Canyon.

"Miranda has a really bizarre, deformed surface," said study lead author Noah Hammond, a planetary scientist at Brown University in Rhode Island. "It's a really beautiful and exotic moon."

Miranda has three giant features known as coronae that are unique among known objects in the solar system.

They are shaped crudely, either like ovals or trapezoids, and each is least 120 miles (200 km) wide.

The coronae are separated from their more heavily cratered surroundings by belts of concentric ridges and troughs, making the coronae look like mismatched patches on a moth-eaten coat.

The three coronae, Arden, Elsinore and Inverness, are named after Scottish locations also mentioned in Shakespeare's plays.

This photo of Uranus' moon Miranda, taken by NASA's Voyager 2 probe in January 1986, shows an unusual "chevron" figure and regions of distinctly differing terrain on the mysterious satellite.

Credit: NASA/JPLView full size image

Researchers have long wondered how the coronae formed.

One possibility is that Miranda may have been disrupted by some catastrophic impact, after which its pieces chaotically reassembled.

The coronae formed as rocky material sank downward, triggering concentric wrinkles on Miranda's surface as it contracted, this idea goes.

Another possibility, one suggested by most scientists in the field, is that the coronae formed as buoyant domes of ice rose, causing Miranda's surface to crumple as matter was added to it.

However, it was not known where the heat to drive this ice upward might have come from. Since Miranda is relatively small, it would have cooled quickly after its creation, and it does not have the radioactive material that Earth possesses to help keep its innards hot.

Now, researchers show the gravitational pull of Uranus may have distorted Miranda enough to heat it up, leading its innards to churn much as Earth's does, thus explaining the coronae.

The gravity of Uranus pulls on Miranda, generating tidal forces, much as Earth's moondoes to Earth.

Tidal forces elsewhere in the solar system can be far greater than tidal effects on Earth, for instance, Jupiter's gravitational pull causes the solid rock surface of its third-largest moon Io to bulge up and down by as much as 300 feet (90 meters), generating enough heat to drive volcanic eruptions.

Miranda's orbit around Uranus was once eccentric, or oval-shaped, moving it closer to and farther from Uranus over time.

Three-dimensional computer simulations of Miranda's interior performed for the new study revealed the resulting tidal forces would repeatedly stretch and squeeze Miranda enough to generate substantial amounts of heat, about 5 gigawatts, or 2.5 times the peak power output of the huge Hoover Dam on the southwestern United States' Colorado River.

This heat would cause Miranda's icy mantle to churn with convection much like Earth's mantle of hot rock does. During convection, warm buoyant ice would have risen to Miranda's surface to contort it and create the coronae.

The research team's computer models accurately explained the locations of the coronae and the deformation patterns within the coronae, Hammond said.

"The features on Miranda may look really strange, but they formed in a way that is really similar to what happens on Earth, where convection in the interior drives surface deformation," Hammond told Space.com.

However, the scientists noted that for convection to drive Miranda's surface deformation, the moon's surface must be much weaker than predicted by laboratory experiments.

"The Earth has the same problem: For convection to deform Earth's surface, rocks have to behave weaker than expected," Hammond said.

"It'd be interesting to see what might explain the weakness seen in the surfaces of Miranda, Earth and elsewhere."

So far, scientists only know what Miranda's southern hemisphere looks like. NASA's Voyager 2 spacecraft photographed this part of the moon during its 1986 Uranus flyby but did not image Miranda's northern hemisphere.

"It'd be really interesting to think about what could be on the other side of Miranda," Hammond said. "Our study predicts there'd be one additional corona on Miranda's other side, and I would love to live long enough for a mission to go back to Uranus and test that hypothesis."

Hammond and his colleague Amy Barr detailed their findings online Sept. 15 in the journal Geology.

The origin of Uranus and Neptune elucidated?

Uranus and Neptune as seen from NASA's Voyager mission. Credit: NASA

A team of French-American researchers led by the UTINAM Institute (CNRS/Université de Franche-Comté) has just proposed a solution to the problematic chemical composition of Uranus and Neptune, thus providing clues for understanding their formation.

The researchers focused on the positioning of these two outermost planets of the Solar System, and propose a new model explaining how and where they formed.

Their results have been published in The Astrophysical Journal on September 20.

Uranus and Neptune, the outermost planets in the Solar System, each have a mass approximately fifteen times that of the Earth, consisting of up to 90% ice, and highly enriched in carbon.

Because of these particular characteristics, the origin of the two planets remains unresolved today.

Earlier models for their formation, as well as observations of the outer Solar System, could not explain how they formed in the area where they are found today.

This area, which is located very far from the Sun, did not contain sufficient building blocks to form Uranus and Neptune quickly enough before the dissipation of the protosolar nebula.

Once the nebula dissipated, it became impossible for the two planets to accrete gaseous envelopes.

The ESA Herschel Space Observatory recently focused on the isotopic composition of Uranus and Neptune, and especially on the deuterium-to-hydrogen ratio (D/H), a tracer used in planetology to examine the origin of the elements that formed the Solar System.

This isotopic ratio is very sensitive to the temperature of the protosolar nebula, being low close to the Sun, and increasing with the distance.

Dynamic models suggest that Uranus and Neptune formed in the same distant region as the comets, and should therefore have a high D/H ratio.

Surprisingly though, the Herschel measurements show that the D/H ratio in the two planets is much lower than that measured in comets.

This study solves all of these problems at once, by proposing a new model based on detailed simulations of the distribution and transport of the most abundant volatile elements in the Solar System's protosolar nebula (H2O, CO and N2).

These simulations show the presence of density "peaks" of solids in regions where nebular temperature is low enough for gas condensation (or ice lines).

The results show that Uranus and Neptune apparently formed on the Carbon Monoxide (CO) ice line, which would explain why they consist of carbon-rich solids but nitrogen-depleted gas.

Accretion of large quantities of CO with low quantities of cometary H2O gives the D/H value measured in the atmosphere of these planets.

Moreover, since the nitrogen ice line is located slightly farther away, the planets formed naturally poor in nitrogen..

The proposed model gives carbon and nitrogen abundances that are consistent with observed values, and establishes that the formation of Uranus and Neptune took place in this distant region.

More information: "The Measured Compositions of Uranus and Neptune from their Formation on the CO Ice Line," Mohamad Ali-Dib, Olivier Mousis, Jean-Marc Petit and Jonathan I. Lunine, Astrophysical Journal, Vol. 793, Issue 1, September 2014. Arxiv.org/abs/1407.2568

Keck II telescope: Vast Stormy weather on Uranus

Massive storms on Uranus captured August 5 and 6, 2014 as seen by Keck II telescope. 

Both images were taken by Imke de Pater (UC Berkeley), Larry Sromovosky and Pat Fry (U. Wisconsin), and Heidi Hammel (AURA) using the near-infrared camera NIRC2 with adaptive optics on the 10-m Keck II telescope at a wavelength of 1.6 micron.

Weather on any planet can be quite unpredictable. As hurricanes threaten the Aloha State, astronomers working at W. M. Keck II telescope on the island of Hawaii were surprised by the appearance of gigantic swirling storm systems on the distant planet Uranus.

During the Voyager encounter with Uranus in 1986, only a scant handful of dim clouds were seen in its atmosphere.

When the planet approached equinox in 2007 (i.e., when the Sun stood high above its equator), large storms developed on the planet, yet most of these faded.

In the past few days, however, astronomers were surprised by a multitude of bright storms on the planet, including one monstrous feature.

"We are always anxious to see that first image of the night of any planet or satellite, as we never know what it might have in store for us," said Imke de Pater, professor at UC Berkeley and team leader.

"This extremely bright feature we saw on UT 6 August 2014 reminds me of a similarly bright storm we saw on Uranus's southern hemisphere during the years leading up to and at equinox".

"Even after years of observing, a new picture of Uranus from Keck II telescope can stop me in my tracks and make me say Wow!," said Heidi Hammel, a member of the observing team.

Since the 2007 equinox, Uranus's northern pole has been coming into view, and the south pole is no longer visible.

The bright feature de Pater refers to was known as the "Berg", because this feature was visible just below the polar haze, and resembled an iceberg peeled off an ice-shelf.

The Berg oscillated in latitude between southern latitudes of 32 and 36 degrees since 2000, and perhaps dated back to the Voyager era (1986).

In 2004 it became much brighter; in 2005 it started to migrate towards the equator and became a very powerful storm system.

In 2009, when it came to within a few degrees of the equator, it dissipated.

The present storm is even brighter than the Berg. Its morphology is rather similar, and the team expects it may also be tied to a vortex in the deeper atmosphere.

From near-infrared images taken at 2.2 micron, the team already determined that the storm must reach high altitudes; they will conduct calculations to determine the precise altitude, but based upon its brightness at those wavelengths the team expects it to reach altitudes near the tropopause (the boundary in Uranus's atmosphere between the troposphere and the stratosphere).

Scanning the skies for Exoplanets and Exomoons in other solar systems

The best prospect for habitable exomoons may be around gas giants. 

Credit: NASA

The first exoplanet was discovered in 1994.

Twenty years later, NASA's exoplanet catalog lists more than 1700 planets confirmed around other stars.

Most of these extra-solar-systems have been measured by changes in light spectra, in stellar motion or dust disks around stars.

Some exoplanets-more than 40 as of today-have even been directly photographed.

Jupiter's moons

One way or the other, we know that exoplanets are out there in abundance, in places we thought they would be and in places we didn't dream a planet could possibly exist. So what comes next? Finding moons.

Exomoons are naturally formed satellites circling around planets in other solar systems. Like the exoplanets themselves, we assume that exomoons are out there in relatively high abundance.

This assumption is based partly upon what we see around us in our own Solar System and partly upon our hypotheses about planetary formation.

Saturn's moons

This is what we observe in our own Solar System: moons are extremely common.

From Earth's one Moon to Jupiter's (currently known) fifty, every planet in the Solar System one astronomical unit or more from the Sun has a natural satellite.

Even Pluto, no longer officially classified as a planet, has a smaller companion circling around it.

Of note, the solid bodies such as Earth and Pluto have very few companions, while gaseous bodies Jupiter, Saturn, Uranus and Neptune have many.

Pluto and Charon

Furthermore, the masses of the Moon and Charon have a very specific relationship to Earth and Pluto in terms of mass: each satellite is about 10-2 the mass of their parent planet.

By contrast, the ratio of satellite masses to parent planet masses for the gas giants is very different: 10-4.

The differences in mass-ratio, how massive the moon is compared to the parent planet, and the differences in composition between the moons of solid planets and those of the gas giants led to a search for different formation scenarios for Earth's moon and the moons of the outer planets.

This is the current hypothesis: that there are two different methods of satellite formation at work in our Solar System.

Amy Barr Mlinar

Both methods were recently reviewed by Dr.Amy Barr Mlinar of Brown University at the Space Telescope Science institute Spring Symposium.

"This has been worked out starting about in the 1960's up through now," said Barr, "You have this [moon/planet] mass ratio of about 10-2 for solid planets, and a [moon/planet] mass ratio of about 10-4 for planets with a gaseous envelope."

Essentially, difference in mass ratios reflects the two completely different origins of our Moon and the satellites of Jupiter.

At the high end of the moon/planet mass ratio, 10-2 are the satellites of solid bodies (Earth and Pluto). These moons were formed from collisions.

Sometime in the distant past an object some large percentage of Earth's size struck the Earth, knocking material away that later coalesced into the Moon. The same is likely true of Charon, Pluto's companion.

Read the full article here

NASA Cassini Image: Looking beyond Saturn to view Uranus

This view from NASA's Cassini spacecraft features a blue planet, but unlike the view from July 19, 2013 (PIA17172 The Day the Earth Smiled) that featured our home planet, this blue orb is Uranus, imaged by Cassini for the first time.

Credit: NASA /JPL-Caltech /Space Science Institute

Uranus is a pale blue in this natural colour image because its visible atmosphere contains methane gas and few aerosols or clouds.

Methane on Uranus and its sapphire-coloured sibling, Neptune, absorbs red wavelengths of incoming sunlight, but allows blue wavelengths to escape back into space, resulting in the predominantly bluish color seen here.

Cassini imaging scientists combined red, green and blue spectral filter images to create a final image that represents what human eyes might see from the vantage point of the spacecraft.

Uranus

Uranus has been brightened by a factor of 4.5 to make it more easily visible. The outer portion of Saturn's A ring, seen at bottom right, has been brightened by a factor of two.

The bright ring cutting across the image center is Saturn's narrow F ring.

Uranus was approximately 28.6 astronomical units from Cassini and Saturn when this view was obtained.

An astronomical unit is the average distance from Earth to the sun, equal to 93,000,000 miles (150,000,000 kilometers).

Neptune

The view was acquired by the Cassini narrow-angle camera at a distance of approximately 614,300 miles (988,600 kilometers) from Saturn on April 11, 2014.

Image scale at Uranus is approximately 16,000 miles (25,700 kilometers) per pixel.

Image scale at Saturn's rings is approximately 4 miles (6 kilometers) per pixel.

In the image, the disk of Uranus is just barely resolved.

The solar phase angle at Uranus, seen from Cassini, is 11.9 degrees.

What happens when the poles flip?

Uranus with its moons and rings. Credit: Hubble

Have you heard the startling news that the Earth's poles might flip?

When will this happen? Can this happen?

First, there's no secret planet hurtling through the Solar System causing chaos and orbital disturbances.

So could the Earth spontaneously physically flip over? Some planets have already been tilted and flipped.

Take a look at Uranus. Its orbital tilt is 98-degrees. We assume the planet started with the same tilt as the rest of the Solar System, and some event in the ancient past caused it to fall over.

It could have collided with another planet, billions of years ago, or gravitational interactions with other giant planets pushed it over.

And then there's Venus, its axial tilt is 177-degrees. That's essentially upside down. Venus is turning in the opposite direction from every other planet in the Solar System.

Standing on the surface of Venus, you would see the Sun rise in the West and set in the East. Astronomers don't know why this happened, perhaps it was gravitational interactions or a collision with another planet.

To actually flip a planet off its axis would take an event so catastrophic that it would devastate the planet.

Don't worry, as far as we know, those kinds of events and interactions stopped happening billions of years ago.

Schematic illustration of Earth’s magnetic field. Credit: Peter Reid

NASA WISE: Uranus and the Planet X myth - debunked

The hunt for Planet X began after Uranus (pictured) was first discovered in 1781 with astrologers hoping it could explain the wobbly orbit of Uranus around the sun

It was an elusive planet that for 200 years appeared to explain Uranus's wobbly orbit and there was the sister sun theorised to be near our solar system that caused asteroids to swerve toward Earth.

There is just one problem: neither "Planet X" nor "Nemesis" ever existed, researchers now say. Although, there is still a trace of doubt.

"The outer solar system probably does not contain a large gas giant planet ("Planet X"), or a small, companion star ("Nemesis")," concluded University of Pennsylvania astronomer Kevin Luhman, who directed the study using NASA's Wide-field Infrared Survey Explorer (WISE) telescope.

The results were published in the most recent edition of The Astrophysical Journal.

Most theories had estimated Planet X to be up to four times the size of Jupiter—the biggest planet in our solar system.

They suggested it would be found some 1,486 billion kilometers (923 billion miles) from the sun, or about 10,000 times farther than the Earth's orbit.

But the images gathered by the telescope did not detect any object larger than Jupiter.

Luhman doesn't rule out the possibility that a planet is lurking somewhere in the asteroid belt.

It would be hard to find if it were closely aligned with a bright star that blinds the telescope or were much smaller than had been theorized.

A computer generated NASA montage obtained 29 August 2002 from images collected by the Voyager 2 spacecraft shows Neptune (Lower-L) as it would appear from a spacecraft approaching Triton, Neptune's largest moon

But after this latest survey, Luhman said the odds of finding one are very unlikely: "That is like a one in a hundred chance."

History of Planet X
Scientists first imagined the existence of Planet X in 1781, when they discovered Uranus, a gas giant that astonished astronomers with its orbital variations, apparently incompatible with Newton's laws of gravity.

Observers concluded that these irregularities could be explained by the existence of another, unknown planet that was exerting its own gravitational force.

Attempts to track this mysterious Planet X led to the discovery of Neptune in 1846. But the estimated mass of Neptune couldn't explain the deviations of Uranus's orbit.

That led astronomers to continue their search for Planet X—which, in turn, led to the discovery of Pluto in 1930. But the dwarf planet was also too small to explain Uranus's irregular path around the sun.

Finally, in the 1990s, researchers determined that they had slightly overestimated the mass of Neptune, which meant the planet could in fact be the reason for Uranus's orbital behaviour.

Yet Planet X believers were still not convinced.

Sister sun killed dinosaurs?
The existence of Nemesis, a sun-like star nearby, was first posited in the 1980s. The star, by occasionally coming closer to the sun, interfered with the orbit of comets and asteroids leading them to occasionally hit the Earth.

Collisions like these are blamed for the five mass extinctions over the last 540 million years—the most recent being the dinosaur extinction 65 million years ago.

"So over the years, there have been different pieces of evidence suggesting there might be something there," Luhman explained to reporters but the WISE telescope didn't find anything.

The hunt for Planet X and Nemesis may have turned up empty, but the study did uncover 3,525 stars and brown dwarfs, celestial objects whose mass puts them between a star and a large planet, within 500 light years of the sun.

"Neighbouring star systems that have been hiding in plain sight just jump out in the WISE data," said Ned Wright, a University of California, Los Angeles astronomer who contributed to the study.

Three centaurs follow Uranus through the solar system

Add caption

Credit: SINC

Astrophysicists from the Complutense University of Madrid have confirmed that Crantor, a large asteroid with a diameter of 70 km has an orbit similar to that of Uranus and takes the same amount of time to orbit the Sun.

Researchers have demonstrated for the first time that this and a further two objects of the group of the Centaurs are co-orbital with Uranus.

Uruguayan astronomer Tabaré Gallardo suggested in 2006 that the asteroids Crantor and 2000 SN331 complete their orbits of the Sun in the same time period as Uranus - an orbit of approximately 84 Earth years.

Now two researchers at the Complutense University of Madrid (UCM, Spain) have confirmed that in the case of Crantor this is true.

"The simulations we have carried out in the Data Processing Centre of the UCM indicate that 2000 SN331 does not have 1:1 commensurability with Uranus, but Crantor does, which means it orbits the Sun in exactly the same time period as the planet," Carlos de la Fuente Marcos, one of the authors of the study, explains to SINC.

In addition, Crantor's orbit has a very similar semi-major axis to that of Uranus, although its eccentricity and inclination vary. The trajectories, figures and animations are published in the journal Astronomy & Astrophysics.

"This 70 km-wide asteroid's orbit is controlled by the Sun and Uranus but is unstable due to disturbances from nearby Saturn," states De la Fuente Marcos.

The researcher also reveals that they found another object, which has been named 2010 EU65 and moves in a similar orbit to Crantor's, "although much more stable because its trajectory is less eccentric."

Similarly, the latest data of a third asteroid, 2011 QF99 - the discovery of which was made public only a few weeks ago - also indicate that its orbit is in line with that of Uranus.

According to the Minor Planet Center, the regulating organization for the naming of asteroids and comets, the three objects that "follow" Uranus belong to the group of the Centaurs.

These icy planetoids endowed with a mythological name orbit the Sun between Jupiter and Neptune.

"Crantor, 2010 EU65 and 2011 QF99 are the first bodies to be documented as co-orbiting with Uranus," affirms De la Fuente Marcos, "although with distinct movements and trajectories."

From the point of view of an observer rotating along with Uranus, both Crantor and 2010 EU65 have "horseshoe" orbits, since they acquire this form as they move towards and away from the planet. In fact, these two centaurs periodically have close encounters with Uranus.

However, 2011 QF99 maintains a more stable, Trojan or "tadpole" orbit, which means that it moves 60 degrees in front of Uranus. This asteroid always maintains a relatively large distance from the planet.

The scientists calculate that the orbits of these three objects associated with Uranus could remain stable for a few million years. In astronomical terms this is not very long.

With the Data Processing Centre's simulations, the same team has identified three new Mars Trojan asteroids with stable orbits of up to 10,000 million years.

More information: Fuente Marcos, C. and Fuenta Marcos, R. Crantor, a short-lived horseshoe companion to Uranus, Astronomy & Astrophysics 551: A114, March 2013.

Fuente Marcos, C. and Fuenta Marcos, R. Crantor, Three new stable L5 Mars Trojans, Monthly Notices of the Royal Astronomical Society Letters 432: 31-35, May 2013.

The Mighty Winds of Uranus and Neptune

This image of Uranus was obtained in 2005 by the Hubble Space Telescope. Rings, southern collar and a bright cloud in the northern hemisphere are visible.

CREDIT: NASA, ESA, and M. Showalt

The powerful winds of Uranus and Neptune are apparently confined to tight layers in both planets, researchers have determined.

These findings could shed light on how those immensely strong winds are born, and how giant planets form and evolve over time, scientists added.

Giant planets in the outer solar system, like Uranus and Neptune, are dominated by winds that can reach supersonic speeds and jet streams 10 to 15 times stronger than those found on Earth, judging by images of how clouds race by on those worlds.

Yohai Kaspi

However, just how deep those winds reached was unknown until now, hidden as those lower depths are beneath those dense layers of clouds.

"This has been an open question for the last 25 years," study lead author Yohai Kaspi, a planetary scientist at the Weizmann Institute of Science in Rehovot, Israel, told reporters.

This image shows schematic of the jet streams on the planet Neptune. Scientist have found that the atmosphere's circulation is characterized by westward flow near the equator with velocities reaching 750 mph (1200 km/hr), and an eastward flow at higher latitudes in both the northern and southern hemispheres with velocities reaching 560 mph (900 km/hr). 

The wind velocities decay towards the planet's dense fluid interior. Image released May 15, 2013. 

CREDIT: Yohai Kaspi, Weizmann Institute of Science/NASA

Kaspi and his colleagues focused on Uranus and Neptune, which are both "ice giants" — massive planets with icy atmospheres.

The winds of Uranus can blow clouds up to 560 miles per hour (900 kilometers per hour), while Neptune's winds can reach up to 1,500 miles per hour (2,400 kilometers per hour), the fastest planetary winds detected yet in the solar system.

The researchers investigated the gravity fields of those worlds using data gathered by NASA's Voyager 2 spacecraft and ground-based telescopes.

The strength of a planet's gravity field depends on its amount of mass, and this strength can vary over the surface of a planet depending on the amount of mass lying under it.

By analyzing the gravity fields of these worlds, the investigators could deduce how their atmospheres circulated.

The scientists discovered the winds blow in relatively thin weather layers no more than 600 miles (1,000 kilometers) deep on both planets. For comparison, Neptune is about 30,600 miles (49,250 km) in diameter, while Uranus is approximately 31,500 miles (50,700 km) wide.

These findings help reveal how these winds originate, researchers said.

Past studies have suggested the winds on Uranus and Neptune might arise one of two ways — either shallow processes in their outer atmospheres, or deeper atmospheric mechanisms extending into their interiors.

The researchers found the windy layers of Uranus and Neptune occupy the outermost 0.15 and 0.2 percent of their masses, respectively, suggesting that shallow processes drive those winds, such as swirling caused by moisture condensing and evaporating in the atmosphere.

This image of Neptune was captured by NASA's Voyager 2 spacecraft during an August 1989. Neptune's Great Dark Spot dominates the center along with bright, white. To the south is the bright feature nicknamed "Scooter." 

Still farther south is the "Dark Spot 2," which has a bright core. Each feature moves eastward at a different velocity, so it is only occasionally that they appear close to each other as shown here 

CREDIT: NASA

The new study has implications for how scientists understand how planets form.

"When it comes to thinking about the effects of dynamics on planetary formation, we're saying the bottom 90 percent of giant planets is static," Kaspi said.

In the future, the Cassini spacecraft currently orbiting Saturn and NASA's Juno probe that is scheduled to reach Jupiter can analyze the gravity fields of those giant planets and help better explain their winds as well.

NASA Scientist Plan Return to Uranus

A pair of enhanced images of Uranus from the Keck telescope on Hawaii are among the best from the Earth. Credit: Lawrence Sromovsky, University of Wisconsin-Madison/ W. M. Keck Observatory

An image of Uranus, its rings and moons from the Hubble space telescope in 1997. Credit NASA/ESA

While spacecraft continue to study the Moon, Mercury, Venus, Mars, Jupiter and Saturn, some space scientists are clamouring for missions to the neglected planets of the Solar System.

A NASA probe, New Horizons, is currently racing towards an ex-planet, Pluto, to speed past and tell us more about that world and its Kuiper Belt relatives. But ice giants Uranus and Neptune have not been properly studied from space since the Voyager missions of the 1980s.

There are no plans currently to return to the most distant planet Neptune. However, NASA has made a Uranus mission the third highest priority for planetary exploration in the 2020s, after another martian rover and further study of Jupiter.

The US financial crisis has put many future missions on hold due to budgetary restraints. But planetary scientists are pressing for such a mission to fly as soon as possible, especially after a similar proposal for a European mision, Uranus Pathfinder, was passed over in 2011.

Uranus: Keck observations brings weather into sharp focus

A paired picture of Uranus, the sharpest, most detailed picture of the distant planet to date, reveals a raft of new details about the planet's enigmatic atmosphere. 

The north pole of Uranus (to the right in the picture) is characterised by a swarm of storm-like convective features, and an unusual scalloped pattern of clouds encircles the planet's equator. 

The infrared image was taken using the Keck II telescope in Hawaii. 

Credit: Lawrence Sromovsky, Pat Fry, Heidi Hammel, Imke de Pater

In 1986, when Voyager swept past Uranus, the probe's portraits of the planet were "notoriously bland," disappointing scientists, yielding few new details of the planet and its atmosphere, and giving it a reputation as the most boring planet of the solar system.

Now, however, thanks to a new technique applied at the Keck Observatory, Uranus is coming into sharp focus through high-resolution infrared images, revealing in incredible detail the bizarre weather of the seventh planet from the sun.

The images were released in Reno, Nev. today (Oct. 17, 2012) at a meeting of the American Astronomical Society's Division of Planetary Sciences and provide the best look to date of Uranus's complex and enigmatic weather.

The planet's deep blue-green atmosphere is thick with hydrogen, helium and methane, Uranus's primary condensable gas.

Larry Sromovsky

Winds blow mainly east to west at speeds up to 560 miles per hour, in spite of the small amounts of energy available to drive them.

Its atmosphere is almost equal to Neptune's as the coldest in our solar system with cloud-top temperatures in the minus 360-degree Fahrenheit range, cold enough to freeze methane.

Large weather systems, which are probably much less violent than the storms we know on Earth, behave in bizarre ways on Uranus, explains Larry Sromovsky, a University of Wisconsin-Madison planetary scientist who led the new study using the Keck II telescope.

"Some of these weather systems," Sromovsky notes, "stay at fixed latitudes and undergo large variations in activity. Others are seen to drift toward the planet's equator while undergoing great changes in size and shape. Better measures of the wind fields that surround these massive weather systems are the key to unraveling their mysteries."

Imke de Pater

To get a better picture of atmospheric flow on Uranus, Sromovsky and colleagues Pat Fry, also of UW-Madison, Heidi Hammel of the Association of Universities for Research in Astronomy (AURA), and Imke de Pater of the University of California at Berkeley, used new infrared techniques to detect smaller, more widely distributed weather features whose movements can help scientists trace the planet's pattern of blustery winds.

"We're seeing some new things that before were buried in the noise," says Sromovsky, a senior staff scientist at UW-Madison's Space Science and Engineering Center.

Heidi Hammel

"My first reaction to these images was 'wow' and then my second reaction was WOW," says AURA's Heidi Hammel, a co-investigator on the new observations and an expert on the atmospheres of the solar system's outer planets.

"These images reveal an astonishing amount of complexity in Uranus's atmosphere. We knew the planet was active, but until now much of the activity was masked by noise in our data."

The complexity of Uranus's weather is puzzling, Sromovsky explains. The primary driving mechanism must be solar energy because there is no detectable internal energy source.

"But the sun is 900 times weaker there than on Earth because it is 30 times further from the sun, so you don't have the same intensity of solar energy driving the system," explains Sromovsky.

"Thus the atmosphere of Uranus must operate as a very efficient machine with very little dissipation. Yet the weather variations we see seem to defy that requirement."

The new Keck II pictures of the planet, according to Sromovsky, are the "most richly detailed views of Uranus yet obtained by any instrument on any observatory.

No other telescope could come close to producing this result." Sromovsky and his colleagues used Keck II, located on the summit of Hawaii's 14,000-foot extinct volcano Mauna Kea, to capture a series of images that, when combined, help increase the signal to noise ratio and thus tease out weather features that are otherwise obscured.

In two nights of observing under superb conditions, Sromovsky's group was able to obtain exposures of the planet that provide a clear view of the planet's cloudy features, including several new to science.

The group used two different filters in an effort to characterize cloud features at different altitudes. "The main objective was to find a larger number of cloud features by detecting those that were previously too subtle to be seen, so we could better define atmospheric motions," Sromovsky notes.

New features found by the Wisconsin group include a scalloped band of clouds just south of Uranus's equator and a swarm of small convective features in the north polar regions of the planet, features that have never been seen in the southern polar regions.

"This is a very asymmetric situation," says the Wisconsin scientist. "There is certainly something different going on in those two polar regions." One possible explanation, is that methane is pushed north by an atmospheric conveyor belt toward the pole where it wells up to form the convective features observed by Sromovsky's group.

"The 'popcorn' appearance of Uranus's pole reminds me very much of a Cassini image of Saturn," adds de Pater.

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Voyager 1 & 2: The Interstellar Mission

The twin Voyager 1 and 2 spacecraft continue exploring where nothing from Earth has flown before.

In the 34th year after their 1977 launches, they each are much farther away from Earth and the Sun than Pluto.

Voyager 1 and 2 are now in the "Heliosheath" - the outermost layer of the heliosphere where the solar wind is slowed by the pressure of interstellar gas.

Both spacecraft are still sending scientific information about their surroundings through the Deep Space Network (DSN).


The primary mission was the exploration of Jupiter and Saturn.

After making a string of discoveries there, such as recording active volcanoes on Jupiter's moon Io and intricacies of Saturn's rings, the mission was extended.

Voyager 2 went on to explore Uranus and Neptune, and is still the only spacecraft to have visited those outer planets.

The adventurers' current mission, the Voyager Interstellar Mission (VIM), will explore the outermost edge of the Sun's domain and beyond.

Mission Objective

The mission objective of the Voyager Interstellar Mission (VIM) is to extend the NASA exploration of the solar system beyond the neighbourhood of the outer planets to the outer limits of the Sun's sphere of influence, and possibly beyond.

This extended mission is continuing to characterize the outer solar system environment and search for the heliopause boundary, the outer limits of the Sun's magnetic field and outward flow of the solar wind.

Penetration of the heliopause boundary between the solar wind and the interstellar medium will allow measurements to be made of the interstellar fields, particles and waves unaffected by the solar wind.

Cupid and Belinda, doomed moons of Uranus

Uranus with its vertical ring system.

A pair of star-cross'd lovers orbits Uranus, and when they rush to meet their fate, the duo could leave the cosmic stage littered with more bodies than the final scene of Hamlet.

But the deaths of the moons Cupid and Belinda might not bring down the curtain on Uranus's satellites. 

Instead they could mark the beginning of a cycle between moons and rings that has been the central drama of the Uranian system for hundreds of thousands of years.

Named mostly after characters in Shakespeare plays, Uranus's inner moons are a tight and mysterious group. 

They orbit closer to the planet and each other than any other set of satellites in the solar system, packing 13 moons into the space of 10,000 kilometres.

Earlier work from 1997 suggested the inner moons would bump into each other, and often. Since then, three new inner moons – Perdita, Cupid and Mab – have been discovered in archival data from Voyager 2 and new images from the Hubble Space Telescope.

Robert French and Mark Showalter of the SETI Institute decided to run orbital simulations to see if the new moons were also in danger.

The result: "Something bad always happened," French says. "Almost no matter what assumptions we make, Cupid is going to die."

The authors think Cupid and Belinda are more likely to break apart than stick together. However, even that scenario leads to multiple collisions, which could solve another of the planet's mysteries.

Material close to a planet tends to get pulled apart into rings, while debris that's sufficiently far away can clump together to form moons. 

In addition to a traditional set of rings and moons, Uranus has a small, faint ring in an anomalous place, just inside the orbit of Cupid. That moon, meanwhile, has such a short life expectancy that French is surprised it exists.

"So we have this ring that shouldn't be there because it should be a moon, and a moon that shouldn't be there because it should smack into something and create a ring," he says. "Perhaps there is a cycle going on."

French suggests that the inner moons and rings are constantly recycling in a process similar to what's happening in Saturn's F ring. "Maybe this isn't the end of Cupid's life," he says. "Maybe it's the middle or the beginning, and it's just not going to last very long."

NASA/ESA Hubble Captures First Images of Unique Auroras on Uranus

(Photo: American Geophysical Union)

Astronomers have captured unique images of auroras above the giant ice planet Uranus for the first time, using the Hubble Space Telescope (HST).

 
Astronomers have captured unique images of auroras above the giant ice planet Uranus for the first time with the help of Hubble Space Telescope, according to the Observatoire de Paris in Meudon in France.

Astronomers found that aurora on Uranus are fainter than they are on Earth because the magnetosphere of Uranus is very poor compared to earth.

Uranian light show consisted of short-lived, faint, glowing dots. Unlike auroras on Earth, which can turn the sky greens and purples for hours, they found the newly detected auroras on Uranus appeared to last only a couple of minutes.

Aurora lights or northern lights are natural display in the sky particularly in the high latitude region on the Earth and other planets.

Northern lights usually occur in the atmosphere when the electrically charged particles from the sun (Solar Wind) enter or strike the earth's magnetosphere. The collision of solar particles on earth magnetosphere creates aurora lights.

Twenty five years ago, astronomers had first witnessed Uranian auroras when the Voyager 2 spacecraft whizzed past the planet and recorded spectra from of the radiant display.

Since then astronomers have continued to observe Uranus's magnetosphere.

"Since that time, we've had no opportunities to get new observations of this very unusual magnetosphere," said Laurent Lamy, reasercher at the Observatoire de Paris in Meudon, France, in a statement.

Lamy and his colleagues provide the details in a paper published by Geophysical Research Letters.

French Astronomers captured these unique images in 2011, when Earth, Jupiter and Uranus were lined up so that the solar wind could flow from the Sun, past Earth and Jupiter, and then toward Uranus.

In mid-September 2011, the Sun had produced a huge X type solar flare. The solar flare was quite intense and it was travelling at a great speed and it took just two days for the solar flare to reach the earth.

After two weeks, the solar wind speed passed Jupiter at 500 kilometers per second. By calculating the speed of the charged particles researchers estimated that it would reach Uranus in mid-November.

Astronomers believe that better understanding of Uranus' magnetosphere could help scientists test their theories of how Earth's magnetosphere functions.

"We have ideas of how things work on Earth and places like Jupiter and Saturn, but I don't believe you really know how things work until you test them on a very different system," said Lamy in an article published by American Geophysical Union journal.

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