The images depict a hurricane in Saturn’s north pole region. The eye of the storm is around 2,000 kilometers (1,250 miles) in diameter. The clouds on the hurricane’s outer edge are travelling at 150 meters per second (330 miles per hour).

“We did a double take when we saw this vortex because it looks so much like a hurricane on Earth,” said Andrew Ingersoll, a Cassini imaging team member at the California Institute of Technology. “But there it is at Saturn, on a much larger scale, and it is somehow getting by on the small amounts of water vapor in Saturn’s hydrogen atmosphere.”

NASA has stated that the storm on Saturn is “locked onto” the planet’s north pole. Cassini was unable to image Saturn’s northern hemisphere using visible light until 2009, when the planet’s equinox passed. Researchers hope that studying the hurricane on Saturn can provide data on how hurricanes on Earth develop and sustain themselves.

“Such a stunning and mesmerizing view of the hurricane-like storm at the north pole is only possible because Cassini is on a sportier course, with orbits tilted to loop the spacecraft above and below Saturn’s equatorial plane,” said Scott Edgington, Cassini deputy project scientist at NASA’s Jet Propulsion Laboratory. “You cannot see the polar regions very well from an equatorial orbit. Observing the planet from different vantage points reveals more about the cloud layers that cover the entirety of the planet.”

(Image courtesy NASA/JPL-Caltech/SSI)

This week, NASA revealed that Saturn has now been added to the short list of places in the Solar System where astronomers have been able to observe collisions occurring as they happen (Earth, the moon, and Jupiter are the others).

NASA’s Cassini probe has captured images of meteoroids hitting the debris that makes up Saturn’s rings. Researchers believe that studying the impact rate on Saturn can help them determine more precisely how the planets in the Solar System formed.

“These new results imply the current-day impact rates for small particles at Saturn are about the same as those at Earth – two very different neighborhoods in our solar system – and this is exciting to see,” said Linda Spilker, a Cassini project scientist at NASA’s Jet Propulsion Laboratory (JPL). “It took Saturn’s rings acting like a giant meteoroid detector – 100 times the surface area of the Earth – and Cassini’s long-term tour of the Saturn system to address this question.”

Cassini scientists studied data for years to find evidence of the tracks the small meteorites left behind. The research has been published in the latest issue of the journal Science.

“We knew these little impacts were constantly occurring, but we didn’t know how big or how frequent they might be, and we didn’t necessarily expect them to take the form of spectacular shearing clouds,” said Matt Tiscareno, lead author of the paper and a Cassini participating scientist at Cornell University. “The sunlight shining edge-on to the rings at the Saturnian equinox acted like an anti-cloaking device, so these usually invisible features became plain to see.”

(Image courtesy NASA/JPL-Caltech/Space Science Institute/Cornell)

The findings, published this week in the journal Nature Physics, show how certain kinds of solar winds can accelerate electrons. NASA in a statement today said that solar wind around Saturn’s magnetic field forms a shockwave that Cassini can use to study the particle acceleration effect.

“Cassini has essentially given us the capability of studying the nature of a supernova shock in situ in our own solar system, bridging the gap to distant high-energy astrophysical phenomena that are usually only studied remotely,” said Adam Masters, lead researcher on the paper and a researcher at the Institute of Space and Astronautical Science.

The detection of electron acceleration around Saturn came just as a strong shockwave was detected by Cassini. The researchers are looking for “quasi-parallel” shockwaves, which occur when a magnetic field and the direction of the shock are closely aligned.

Shockwaves, such as those from a supernova or solar wind, are common in the universe. When they hit magnetic fields with certain orientations, particles from the shockwave can be accelerated to close the speed of light. These interactions, scientists believe, could be the source of much of the cosmic rays seen in the universe.

(Image courtesy ESA)

The study, published this week in the journal Proceedings of the National Academy of Sciences, states that the smog on Titan begins to form when solar radiation excites nitrogen and methane molecules in the ionosphere, creating a “soup” of negative and positive ions. Collisions among these molecules allows them to grow into more complex aerosols, which coagulate when they reach a lower part of the atmosphere. Eventually the molecules produce the hydrocarbon rain that famously creates the lakes seen on Titan’s surface.

The researchers, based at the University of Reims, looked at data from three different Cassini instruments during the study. Data from Cassini’s plasma spectrometer, its ion and neutral mass spectrometer, and its radio and plasma wave science experiment were examined and compared to data from the Huygens probe, which descended to the surface of Titan in 2005.

Titan is the only other object in the soar system known to have stable liquid on its surface. In December of 2012 the ESA released a high-definition photo of a river valley that runs for over 400 km (248 miles) on the surface of Titan. The picture above shows a flash of sunlight that is reflected off a lake on Titan. The phenomenon is known as a specular reflection.

“This Saturn storm behaved like a terrestrial hurricane – but with a twist unique to Saturn,” said Andrew Ingersoll, co-author of the paper and a Cassini imaging team member. “Even the giant storms at Jupiter don’t consume themselves like this, which goes to show that nature can play many awe-inspiring variations on a theme and surprise us again and again.”

The storm was first detected in December of 2010, forming from warm gas in the planet’s atmosphere. It began moving west along 33 degrees north latitude, spinning clockwise. The storm eventually stretched 190,000 miles (300,000 kilometers) around the planet. With no mountains or other land to impede it, the storm eventually ran into itself in June 2011 and faded away.

“This thunder-and-lightning storm on Saturn was a beast,” said Kunio Sayanagi, lead author on the paper and a Cassini imaging team associate at Hampton University. “The storm maintained its intensity for an unusually long time. The storm head itself thrashed for 201 days, and its updraft erupted with an intensity that would have sucked out the entire volume of Earth’s atmosphere in 150 days. And it also created the largest vortex ever observed in the troposphere of Saturn, expanding up to 7,500 miles (12,000 kilometers) across.”

Though the storm was the longest-running of the massive storms that occur in Saturn’s northern hemisphere every 30 (Earth) years, it isn’t the longest storm ever detected on the gas giant. That honor goes to a storm 100 times smaller, which formed in the southern hemisphere’s “storm alley” and lasted 334 days in 2009.

“Cassini’s stay in the Saturn system has enabled us to marvel at the power of this storm,” said Scott Edgington, Cassini’s deputy project scientist at NASA’s Jet Propulsion Laboratory (JPL). “We had front-row seats to a wonderful adventure movie and got to watch the whole plot from start to finish. These kinds of data help scientists compare weather patterns around our solar system and learn what sustains and extinguishes them.”

“Most of the Saturnian satellites – Titan’s siblings – have thousands and thousands of craters on their surface,” said Catherine Neish, a Cassini radar team associate based at NASA’s Goddard Space Flight Center. “So far on Titan, of the 50 percent of the surface that we’ve seen in high resolution, we’ve only found about 60 craters. It’s possible that there are many more craters on Titan, but they are not visible from space because they are so eroded. We typically estimate the age of a planet’s surface by counting the number of craters on it (more craters means an older surface). But if processes like stream erosion or drifting sand dunes are filling them in, it’s possible that the surface is much older that it appears.”

The new research is the first quantitative estimate of how much the weather on Titan has eroded its surface. The moon is the only one known in our solar system to have a thick atmosphere. It is also known to have seas of organic compounds, such as ethane and methane, on its surface.

Methane is broken down in Titan’s atmosphere by sunlight, then recombined into more complex hydrocarbons. These molecules form an orange smog that envelops the planet. Some of the larger particles from the atmosphere, say scientists, rain down and become bound together into an exotic form of sand.

“Since the sand appears to be produced from the atmospheric methane, Titan must have had methane in its atmosphere for at least several hundred million years in order to fill craters to the levels we are seeing,” said Neish.

Titan’s methane levels are somewhat of a mystery, however. Researchers estimate that current levels of methane on Titan would be broken down within tens of millions of years. This suggests that the moon either had much more methane in the past, or is replenishing its methane in some way.

(Image courtesy NASA/JPL-Caltech/ASI/GSFC)

“One of the most intriguing questions about these lakes and seas is whether they might host an exotic form of life,” said Jonathan Lunine, co-author of the research and a Cassini interdisciplinary Titan scientist at Cornell University. “And the formation of floating hydrocarbon ice will provide an opportunity for interesting chemistry along the boundary between liquid and solid, a boundary that may have been important in the origin of terrestrial life.”

Floating methane ice was thought to be impossible on Titan, since solid methane is more dense than liquid methane, and would sink. The new research considers the interplay between Titan’s lakes and the moon’s atmosphere. Scientists found that the types of methane and ethane ice that might exist on Titan will float if the temperature is below 90.4 kelvins (297 degrees Fahrenheit), methane’s freezing point.

“We now know it’s possible to get methane-and-ethane-rich ice freezing over on Titan in thin blocks that congeal together as it gets colder — similar to what we see with Arctic sea ice at the onset of winter,” said Jason Hofgartner, lead author of the paper and a Natural Sciences and Engineering Research Council of Canada scholar at Cornell. “We’ll want to take these conditions into consideration if we ever decide to explore the Titan surface some day.”

Titan is the only other object in our solar system besides Earth known to have bodies of liquid on its surface. Its seas are composed of organic molecules that are believed to have been the building blocks for life on Earth.

The photo seen above (a larger version of which can be seen here) was taken using NASA’s Spitzer Space Telescope. the infrared image depicts the giant star Zeta Ophiuchi as it hurtles through space, causing a wave in the dust in its path.

Astronomers believe Zeta Ophiuchi, which is 20 times more massive than our sun, was once a companion star to an even larger star. When the larger star’s life ended, Zeta Ophiuchi was explosively ejected from its system.

The above image of Saturn was taken by NASA’s Cassini probe. A larger version can be seen by clicking the photo. It shows a backlit view of the planet Saturn and its rings taken during Cassini’s 174th orbit of the giant planet. The two small objects in the bottom-left of the photo are Saturn’s moons Enceladus and Tethys.

Cassini, which has been studying Saturn and its numerous moons since 2004, was intentionally positioned within Saturn’s shadow for the pic. It’s a perspective Cassini hasn’t had since 2006 when it took the “In Saturn’s Shadow” photo – one of the most popular Cassini images to date, according to NASA.

“Of all the many glorious images we have received from Saturn, none are more strikingly unusual than those taken from Saturn’s shadow,” said Carolyn Porco, Cassini’s imaging team lead at the Space Science Institute.

The Cassini spacecraft recently celebrated its 15th birthday since its launch back in 1997. In its time in orbit, the probe has launched the Huygens probe to the surface of Titan, where hydrocarbon lakes have also been discovered.

(Images courtesy NASA/JPL-Caltech/Space Science Institute)

On Friday, from its vantage point in orbit around Saturn, the VIMS will be used to track Venus as it travels across the face of the sun. A similar Venus transit could be seen from Earth earlier this summer, but Friday’s transit will be the first time a spacecraft has tracked the transit of a planet in our solar system from beyond Earth.

The VIMS will collect data on Venus’ atmosphere during the event. The observations are also a chance for astronomers to test the VIMS’s ability to observe planets outside the solar system, in an effort to reduce the amount of signal noise. The instrument has already been used to observe a transit by an exoplanet called HD 189733b.

“Interest in infrared investigations of extrasolar planets has exploded in the years since Cassini launched, so we had no idea at the time that we’d ask VIMS to learn this new kind of trick,” said Phil Nicholson, the VIMS team member based at Cornell University. “But VIMS has worked so well at Saturn so far that we can start thinking about other things it can do.”

Since Cassini’s launch in 1997, astronomers have used NASA’s Hubble and Spitzer space telescopes to identify numerous exoplanets. Scientists are hoping to use Cassini’s VIMS to investigate the atmospheres of those planets, in particular whether they contain methane or other hydrocarbons.

The VIMS has also been used in another novel way recently. Back in April 2012, astronomers used the instrument to take thermal data from warm fissures located on Saturn’s moon Enceladus.

“For the first time, we were able to see that the jets coming from the surface of Enceladus originated in very small, very hot spots,” said Bonnie Buratti, a VIMS scientist at NASA’s Jet Propulsion Laboratory. “This new observation is good evidence for liquid water underneath the surface.”

(Images courtesy NASA/JPL/University of Arizona)

“Though there are some short, local meanders, the relative straightness of the river valley suggests it follows the trace of at least one fault, similar to other large rivers running into the southern margin of this same Titan sea,” said Jani Radebaugh, a Cassini radar team associate at Brigham Young University. “Such faults – fractures in Titan’s bedrock – may not imply plate tectonics, like on Earth, but still lead to the opening of basins and perhaps to the formation of the giant seas themselves.”

Researchers explained that they believe the river is filled with liquid because it is dark along its entire extent in the image. This indicates a smooth surface, and Titan is the only other object in the solar system known to have stable liquid on its surface. The liquid likely isn’t water, though. Titan’s environment contains liquid hydrocarbons, such as ethane and methane.

“This radar-imaged river by Cassini provides another fantastic snapshot of a world in motion, which was first hinted at from the images of channels and gullies seen by ESA’s Huygens probe as it descended to the moon’s surface in 2005,” said Nicolas Altobelli, ESA’s Cassini Project Scientist.

The Cassini probe recently celebrated its 15th birthday since launch. In its time around Saturn, the probe has found lakes on Titan, signs of water ice on Enceladus, and followed huge storms in Saturn’s atmosphere.

(Image courtesy NASA/JPL–Caltech/ASI)