NASA Cassini Image: Saturn's Moon Tethys in Sunlight

Credit: NASA/JPL-Caltech /Space Science Institute

Tethys, like many moons in the solar system, keeps one face pointed towards the planet around which it orbits.

Tethys' anti-Saturn face is seen here, fully illuminated, basking in sunlight.

On the right side of the moon in this image is the huge crater Odysseus.

The Odysseus crater is 280 miles (450 kilometers) across while Tethys is 660 miles (1,062 kilometers) across.

See PIA07693 for a closer view and more information on the Odysseus crater.

This view looks toward the anti-Saturn side of Tethys.

North on Tethys is up and rotated 33 degrees to the right.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 15, 2013.

The view was acquired at a distance of approximately 503,000 miles (809,000 kilometers) from Tethys. Image scale is 3 miles (5 kilometers) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency.

The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C.

The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

NASA Cassini: Rhea's Day in the Sun

A nearly full Rhea shines in the sunlight in this recent Cassini image. 

Rhea (949 miles, or 1,527 kilometers across) is Saturn's second largest moon.

Lit terrain seen here is on the Saturn-facing hemisphere of Rhea. 

North on Rhea is up and rotated 43 degrees to the left. 

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Sept. 10, 2013.

The view was obtained at a distance of approximately 990,000 miles (1.6 million kilometers) from Rhea. 

Image scale is 6 miles (9 kilometers) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. 

The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. 

The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. 

The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission, and saturn.jpl.nasa.gov. 

The Cassini imaging team homepage.
Image Credit: NASA/JPL-Caltech/Space Science Institute

NASA Messenger: Sunlight on the Side of the Planet Mercury

Another day, another beautiful view of Mercury's horizon. 

In this scene, which was acquired looking from the shadows toward the sunlit side of the planet, a 120-km (75 mi.) impact crater stands out near the center.

Emanating from this unnamed crater are striking chains of secondary craters, which gouged linear tracks radially away from the crater.

While this crater is not especially fresh (its rays have faded into the background), it does appear to have more prominent secondary crater chains than many of its peers.

This image was acquired on Oct. 2, 2013 by the Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS) aboard NASA's MESSENGER spacecraft, as part of the MDIS's limb imaging campaign.

Once per week, MDIS captures images of Mercury's limb, with an emphasis on imaging the southern hemisphere limb.

These limb images provide information about Mercury's shape and complement measurements of topography made by the Mercury Laser Altimeter (MLA) of Mercury's northern hemisphere.

The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation are unraveling the history and evolution of the solar system's innermost planet.

During the first two years of orbital operations, MESSENGER acquired over 150,000 images and extensive other data sets. MESSENGER is capable of continuing orbital operations until early 2015.

Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

ISS Astronauts Watching the Sunlight on Cape Cod Bay

Credit: NASA

A Russian Soyuz spacecraft and the solar panel of a Russian Progress-M52 cargo carrier docked to the International Space Station float above the Earth on May 4, 2013. 

A stretch of Canada’s Atlantic coast (to the Labrador Sea) and the northeastern U.S. shines below. Cape Cod and Long Island are visible at upper center of the frame.

Aberdeen Scientists Find Link Between Light Deficiency and Multiple Sclerosis

Aberdeen scientists have found that artificial sunlight can have a “striking effect” in helping treat sufferers of diseases such as multiple sclerosis.

Researchers from Aberdeen University studied patients in the north of Scotland – which has the highest rate of MS in the UK - who were being treated during winter with artificial UV (ultraviolet)-B light therapy for skin diseases caused by their immune systems acting inappropriately.

The research - published in the Journal of Allergy and Clinical Immunology – shows how UV-B light boosts vitamin D, as well as cells in our body that are responsible for regulating or balancing the immune system. Vitamin D is made in our bodies by UV-B light from the sun.

Some studies have suggested a link between vitamin D deficiency and autoimmune diseases such as MS.

This possible link might also explain the increasing prevalence of autoimmune disease among those living far from the equator, where there are lower levels of winter sun.

Autoimmune diseases - like MS and type 1 diabetes - are diseases where the immune system mistakenly attacks the body’s own tissues or harmless substances that enter the body.

Dr Anthony Ormerod, clinical reader in dermatology at the university, said: “Our study shows that UV-B light, which mimics sunshine, can have a striking effect on the immune system of patients.

“We found that UV-B light boosted the production of vitamin D, and of regulatory T cells, which play an important role keeping our immune systems in check.

“Our findings have important implications for future interventions including the recommendations for healthy lifestyle and a possible role for phototherapy and/or vitamin D supplementation in the prevention or treatment of autoimmune and inflammatory diseases.

“While too much exposure to sunlight is harmful and increases skin cancer risk, these results suggest that subjects in our study would have some benefits from small amounts equivalent to summer exposure in the winter but more work needs to determine the role of sunlight and the role of supplementing the diet with vitamin D.”

Dr Helen Macdonald, senior lecturer in nutrition and translational musculoskeletal research at the university and chair of the National Osteoporosis Society Nutrition and Lifestyle forum, said: “There are risks associated with high levels of both therapies, so it is important that we get the balance right.

“We would also want to stress that we are not advocating sun bed use since this is not the same type of radiation produced by sun beds which already have well-documented health risks.

“The average dose of UV light that the volunteers received was the equivalent to sunlight exposure in Aberdeen over spring and summer and further work is required to determine if lower doses are effective.”

Professor Mark Vickers, chair in applied medicine at the university, added: “Ours is the first study to demonstrate in patients a cause and effect between UV light, vitamin D and systemic immune function in people.”

Artificial Lightings Seen in Kuiper Belt: Alien World?

ET watchers may be able to find an alien world through telescopes that may spot artificial lightings "out there."

A new study points to the possibility of finding extraterrestrial civilizations that may have also developed artificial lighting sources which our next generation telescopes can detect.

Researchers Abraham Loeb from Harvard and Edwin L. Turner of Princeton, said it is possible to peer into space and spot artificially illuminated objects, adding that current optical telescopes and surveys have the ability to see this amount of light at the edge of our Solar System and observations with large telescopes can measure a Kuiper Belt Objects spectra to determine if they are illuminated by artificial lighting.

Distinguishing an artificial illumination from solar illumination on KBO with typical albedo may be tricky, but the researchers said the existing telescopes and surveys can spot the difference as it will carry the dead give-away which is the spectral signature.

According to Loeb and Turner, our civilization uses two basic classes of illumination, thermal (incandescent light bulbs) and quantum (light emitting diodes and fluorescent lamps). "Such artificial light sources have different spectral properties than sunlight.

The spectra of artificial lights on distant objects would likely distinguish them from natural illumination sources, since such emission would be exceptionally rare in the natural thermodynamic conditions present on the surface of relatively cold objects.

Therefore, artificial illumination may serve as a lamppost which signals the existence of extraterrestrial technologies and thus civilizations," the researchers said.

Not all random light source detected where there should be darkness might be considered a sign of life, the study said, as there are many factors which could contribute to illumination, such as viewing angle, backscattering, surface shadowing, outgassing, rotation, surface albedo variations and more.

Mars Express: Mars' Glowing North Pole

An oustanding image of the North Pole of Mars from a VMC observation on the 30th September. The polar cap of the planet can just be seen in the middle of this image, with low sunlight glinting off the patches of snow and ice surrounding it.

As Earth heads into Northern hemisphere autumn, Mars is also in Northern autumn at the moment and this view captures beautifully the impression of low sunlight in the Northern parts of Mars, with ice and snow signalling the coming winter.

NASA Mercury Messenger Finds Surprises

On its third swing past Mercury, NASA’s Mercury Messenger spacecraft discovered an unexpectedly young lava plain, rapid rufflings of the planet’s weak magnetic field and an unanticipated dance of elements in the thin atmosphere.

“I think the biggest surprise for the community is that the planet is turning out to be much more dynamic than people appreciated,” said Sean C. Solomon of the Carnegie Institution of Washington who is the principal investigator for the Messenger mission.

The flyby occurred in September, when the spacecraft swooped within 142 miles of Mercury’s surface at 12,000 miles per hour, but the findings of that flyby just appeared in three papers the journal Science published last week on its Web site.

Within the 180-mile-wide double-ring Rachmaninoff crater, Messenger photographed flat, smooth plains that scientists interpreted as the hardened outflow of lava. Based on the number of smaller impact craters, the age of the volcanic deposits within Rachmaninoff is probably less than two billion years, said Louise K. Procktor of the Johns Hopkins University Applied Physics Laboratory and lead author of the paper that examined the crater.

While not recent, that would still suggest that Mercury was volcanically active well into its middle age, given that it formed 4.5 billion years ago with the rest of the solar system.

“It is quite a big surprise,” Dr. Procktor said.

Mercury, not much more than 3,000 miles in diameter, is by far the smallest of the planets, and thus many thought it would have cooled off in less than a billion years. But Mercury’s mantle may not rise and fall in convective patterns as in larger planets like Earth, and that may have kept the heat inside for more than two billion years. By imparting heat and relieving pressure, the impact of the meteoroid that formed the crater may have helped melt rocks that were already close to melting point.

Messenger’s measurements also detected rapid fluctuations in Mercury’s magnetic field as it shifted from one side of the planet to the other. Such fluctuations occur around Earth in a matter of hours. Around Mercury, the fields shifted in minutes.

“It looked as though we were seeing a complete collapse of the magnetic field,” Dr. Solomon said. “This is an incredibly dynamic magnetosphere.”

The third paper looked at Mercury’s tenuous atmosphere, which consists of atoms knocked off the surface by sunlight, charged particles and dust-size meteoroids. One surprise was that near the equator, the concentration of calcium was higher near sunrise than sunset, but that effect was not seen for sodium or magnesium.

Because only calcium and not the other elements exhibits this behavior, “We can’t explain it,” said Ronald J. Vervack Jr., another scientist at the Johns Hopkins laboratory and lead author of that Science paper. “They just don’t look the same, and they don’t look the same anywhere we look,” he said. “Which is a bit puzzling, because we expected there to be some similarities.”

A tail of sodium that had been seen behind Mercury during the first two flybys, in January 2008 and October 2008, was much diminished in the third flyby. The reason was that Mercury was in a different part of its elliptical orbit, and the resulting change in velocity diminished the power of sunlight that was sweeping the sodium atoms away from Mercury into the tail.

A clearer picture should start to emerge next year. The spacecraft, launched in 2004, has been doing a gravitational do-si-do with the inner planets to slow down as it spirals inward and gets in position to enter orbit around Mercury in March.