Posted on by Nancy Atkinson

New Webb Telescope Technologies Already Helping Human Eyes

Image of the Scanning Shack Hartmann System (SSHS), a pair of large mirror test stations used to measure the mirror segments of the Webb telescope. As part of that SSHS program, several improvements were made to the wavefront sensor technology that now allow eye health instruments to be aligned more precisely. Credit: Abbott Medical Optics Inc.

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Editor’s note: This NASA press release provides just one example of how developing technology for space missions often has practical, beneficial and sometimes unintended applications on Earth.

Even while construction of the James Webb Space Telescope is underway on the most advanced infrared vision of any space observatory, its technologies are already proving useful to human eye health here on Earth.

“The Webb telescope program has enabled a number of improvements in measurement technology for astronomy, mirror fabrication, and measurement of human eyes, diagnosis of ocular diseases and potentially improved surgery,” said Dr. Dan Neal, Research Fellow at Abbott Medical Optics Inc. in Albuquerque, N.M.

The Webb telescope will be the most scientifically powerful telescope NASA has ever built — 100 times more powerful than the Hubble Space Telescope. The Webb telescope will find the first galaxies that formed in the early universe, connecting the Big Bang to our own Milky Way Galaxy. It will also peer through dusty clouds to see stars and planets being born, connecting star formation in our own galaxy with the solar system.

“The advanced wavefront sensing technology developed for testing the Webb telescope’s 18 primary mirrors led to the new applications in other areas,” said Tony Hull of L3 Integrated Optical Systems Division-Tinsley Facility in Richmond, Calif., where the Webb’s mirrors were recently polished to accuracies of less than one millionth of an inch.

“Wavefront sensing” is used to measure shape of the mirrors during fabrication and control the optics once the telescope is in orbit.

Ophthalmologists routinely use wavefront technology to measure aberrations of the eye. Those measurements help with diagnosis, research, characterization and planning treatment of eye health issues.

“The technology also provides more accurate eye measurements for people about to undergo Laser Refractive Surgery,” Neal said. “To date 10-12 million eyes have been treated with Lasik procedures in the U.S. alone. As technology improves, so does the quality of these procedures.”

James Webb Space Telescope. Credit: NASA

A new “scanning and stitching” technology developed for the Webb telescope led to a number of innovative instrument concepts for more accurate measurement for contact lenses and intra-ocular lenses. Another benefit to eye health is that this technique can help “map” the topography of the eye more accurately.

Think of the surface of your eye as being as dented as the surface of the moon. Precise measurements of your eye’s surface are helpful when assessing eyes for contact lenses. The scanning and stitching technology improvements have enabled eye doctors to get much more detailed information about the shape and “topography” of your eye, and do it in seconds rather than hours. Four patents have been issued as result of innovations driven by the Webb telescope program. “These tools are now used to align and build the next generation of measuring devices for human eyes,” Neal said.

“The lasting impact of the Webb telescope may go beyond the vision of astronomers seeking to see the distant universe; the impact may be a better national technology base and better vision for people everywhere,” Hull said.

NASA’s Innovative Partnerships Program Office (IPPO) is making available wavefront sensing and adaptive optics technologies, procedures and lab equipment to private industry through its “Can you See it Now?” campaign. All of the technologies associated with the campaign are available for licensing and can be found at http://ipp.gsfc.nasa.gov/wavefront.

Posted on by Ken Kremer

Last Towback of a Flight Worthy Space Shuttle – Atlantis Post Touchdown Photo Album

Remember when there was a Space Shuttle. Atlantis flew the final flight of NASA’s Space Shuttle Era on the STS-135 mission and was the last flight worthy orbiter to be towed back from the Shuttle Landing Facility. Atlantis touched down on July 21, 2011 at the Kennedy Space Center. Credit: Ken Kremer

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Space Shuttle Atlantis closed out NASA’s Space Shuttle Era with a safe touchdown on July 21, 2011 at the Kennedy Space Center in Florida at the conclusion of the STS-135 mission, the 135th and final shuttle mission.

I was extremely fortunate to be an eyewitness to history and one of the lucky few journalists permitted by NASA to follow along as Atlantis took her historic final journey back from wheels stop at Runway 15 at the Shuttle Landing Facility as a flight worthy orbiter.

A convoy of 25 specialized vehicles safe each orbiter after landing. Some four hours later, Atlantis was towed off the runway with a diesel powered tractor for about 2 miles along the tow way leading to the Orbiter Processing Facility which lies adjacent to the Vehicle Assembly Building (VAB) at KSC.

The STS-135 crew consisted of Shuttle Commander Chris Ferguson, Pilot Doug Hurley and Mission Specialists Sandra Magnus and Rex Walheim.

Check out my Towback Photo Album below, and prior album from wheels stop at the shuttle runway earlier in the day, here:

Atlantis towed nose first from runway 15 at the Shuttle Landing Facility at KSC.
Credit: Ken Kremer (kenkremer.com)
Atlantis towback from shuttle landing strip on July 21, 2011. Credit: Ken Kremer
Atlantis and post landing convoy vehicles. Credit: Ken Kremer
Impressionistic Atlantis. Credit: Ken Kremer
Convoy of 25 specialized vehicles tow Atlantis from the runway to the Orbiter Processing Facility.
Credit: Ken Kremer
Convoy crew waves to media. Credit: Ken Kremer
Convoy of 25 specialized vehicles tow Atlantis two miles along tow way from the runway to the Orbiter Processing Facility. Credit: Ken Kremer
Atlantis heads to the Orbiter Processing Facility adjacent to Vehicle Assembly Building at KSC.
Credit: Ken Kremer

Read my features about the Final Shuttle mission, STS-135:
Wheels Stop ! With Awesome Atlantis on the Shuttle Runway – Photo Gallery Part 1
Ghostly Landing of Atlantis Closes America’s Space Shuttle Era Forever
Love of Science Drives Last Shuttle Commander – Chris Ferguson Brings Science Museum to Orbit
Revolutionary Robotic Refueling Experiment Opens New Research Avenues at Space Station
Water Cannon Salute trumpets recovery of Last Shuttle Solid Rocket Boosters – Photo Album
Shuttle Atlantis Soars to Space One Last time: Photo Album
Atlantis Unveiled for Historic Final Flight amidst Stormy Weather
Counting down to the Last Shuttle; Stormy weather projected
Atlantis Crew Jets to Florida on Independence Day for Final Shuttle Blastoff
NASA Sets July 8 for Mandatory Space Shuttle Grand Finale
Final Shuttle Voyagers Conduct Countdown Practice at Florida Launch Pad
Final Payload for Final Shuttle Flight Delivered to the Launch Pad
Last Ever Shuttle Journeys out to the Launch Pad; Photo Gallery
Atlantis Goes Vertical for the Last Time
Atlantis Rolls to Vehicle Assembly Building with Final Space Shuttle Crew for July 8 Blastoff

Posted on by Tammy Plotner

Amber Waves Of Energy

These jets, known as spicules, were captured in an SDO image on April 25, 2010. Combined with the energy from ripples in the magnetic field, they may contain enough energy to power the solar wind that streams from the sun toward Earth at 1.5 million miles per hour. Credit: NASA/SDO/AIA

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Have you ever seen the hot summer wind blow across a ripening field of wheat? If so, you’re familiar with the rippling effect. Now imagine that same crop – only the stalks are 32,000 feet high and on the surface of the Sun. This cascading effect is called Alfvén waves.

Thanks to NASA’s Solar Dynamics Observatory (SDO), we’re now able to see the effect of Alfvén waves, track their movements and see how much energy is being carried along. These new findings have enlightening solar researchers and may be the key to two other enigmatic solar occurrences – the intense heating of the corona to some 20 times hotter than the Sun’s surface and solar winds that blast up to 1.5 million miles per hour.

“SDO has amazing resolution so you can actually see individual waves,” says Scott McIntosh at the National Center for Atmospheric Research in Boulder, Colo. “Now we can see that instead of these waves having about 1000th the energy needed as we previously thought, it has the equivalent of about 1100W light bulb for every 11 square feet of the Sun’s surface, which is enough to heat the Sun’s atmosphere and drive the solar wind.”

Credit: NASA/SDO/AIA

As McIntosh points out in his July 28 Nature article, Alfvén waves are pretty simple. Their movement undulates up and down the magnetic field lines similar to the way a vibration travels along a guitar string. The plasma field enveloping the Sun moves in harmony with the field lines. The SDO can “see” and track this movement. Although the scenario is much more complex, understanding the waves is key to understanding the nature of the Sun-Earth connection and other less clear cut questions such as what causes coronal heating and speeds of the solar wind.

“We know there are mechanisms that supply a huge reservoir of energy at the sun’s surface,” says space scientist Vladimir Airapetian at NASA’s Goddard Space Flight Center in Greenbelt, Md. “This energy is pumped into magnetic field energy, carried up into the sun’s atmosphere and then released as heat.” But determining the details of this mechanism has long been debated. Airapetian points out that a study like this confirms Alfvén waves may be part of that process, but that even with SDO we do not yet have the imaging resolution to prove it definitively.

Hannes Alfvén first theorized the waves in 1942, but it wasn’t until 2007 that they were actually observed. This proved they could carry energy from the Sun’s surface to the atmosphere, but the energy was too weak to account for the corona’s high heat. This study says that those original numbers may have been underestimated. McIntosh, in collaboration with a team from Lockheed Martin, Norway’s University of Oslo, and Belgium’s Catholic University of Leuven, analyzed the great oscillations in movies from SDO’s Atmospheric Imagine Assembly (AIA) instrument captured on April 25, 2010. “Our code name for this research was ‘The Wiggles,'” says McIntosh. “Because the movies really look like the Sun was made of Jell-O wiggling back and forth everywhere. Clearly, these wiggles carry energy.”

The “wiggles” – known as spicules – were then modeled against Alfvén waves and found to be a good match. Once pinpointed, the team could then could analyze the shape, speed, and energy of the waves. “The sinusoidal curves deviated outward at speeds of over 30 miles per second and repeated themselves every 150 to 550 seconds. These speeds mean the waves would be energetic enough to accelerate the fast solar wind and heat the quiet corona.” says the team. “The shortness of the repetition – known as the period of the wave – is also important. The shorter the period, the easier it is for the wave to release its energy into the coronal atmosphere, a crucial step in the process.”

According to preliminary data, the spicules leaped to coronal temperatures of at least 1.8 million degrees Fahrenheit. The pairing of Alfvén waves and heat may just be what it takes to keep the corona at its current temperature… but not enough to cause radiation bursts. “Knowing there may be enough energy in the waves is only one half of the problem,” says Goddard’s Airapetian. “The next question is to find out what fraction of that energy is converted into heat. It could be all of it, or it could be 20 percent of it – so we need to know the details of that conversion.”

More study? You betcha’. And the SDO team is up to the task.

“We still don’t perfectly understand the process going on, but we’re getting better and better observations,” says McIntosh. “The next step is for people to improve the theories and models to really capture the essence of the physics that’s happening.”

Original Story Source: NASA SDO News.

Posted on by Tammy Plotner

Peace In The Light… An Orion Sunset

NGC 2023 - Credit: ESA/Hubble & NASA

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Here the stellar winds are carving out a cavity in a vast reflection nebula. It’s an area of Orion that many of us have seen before – but not like the Hubble Space Telescope reveals it. Located right next door to the famous Horsehead Nebula, NGC 2023 can be glimpsed in a telescope as a tiny patch of light that closely resembles its more famous cousin – the Orion Nebula. Spanning approximately four light years across and located some 1500 light-years from Earth, this awesome visage conjures up a peaceful picture of the setting Sun.

However, there’s no sun slipping beyond a horizon in NGC 2023. Hidden inside is a hot, newborn star illuminating the dusty cloud of gas which is its womb. Radiation pressure runs rampant from this massive young B-type star hidden just outside the edge of this image – its winds blowing the material away from it and forming the fanciful shapes we see. Caught in the act are young proto-stars awaiting their turn to be born.

Unlike our Earthly clouds, the clouds we see here are 5000 times denser than the interstellar medium. It is here where weird green clumps could be Herbig-Haro objects – the product of high-speed gases impacting the diaphanous material and creating shockwaves. Their lives are short – lasting only a few thousand years – but what an image they create! If only they could sing…

“I can’t light no more of your darkness… All my pictures seem to fade to black and white…I’m growing tired and time stands still before me… Frozen here on the ladder of my life.”

Original Story Source: Hubble News Photo Release.

Posted on by Tammy Plotner

Voorwerpje… And Away!

UGC 7342 in H-Alpha - Credit: Galaxy Zoo

[/caption]It’s 28 pages long and it has been submitted to the Monthly Notices of the Royal Astronomical Society. It’s filled with exciting new discoveries. What is it? Try the Galaxy Zoo’s latest findings… the Great Voorwerpje Round-up!

“Eighteen thousand candidate active galactic nuclei. One hundred ninety-nine Zooites. A hundred fifty-four possible galaxies with clouds, of which 49 became targets for spectra. And finally, nineteen certified Voorwerpjes – giant clouds of gas ionized by a central active nucleus, like Hanny’s Voorwerp but smaller (and sometimes not all that much smaller) and dimmer.” says Bill Keel. “Of these clouds, many (including the largest) are new discoveries.”

The Galaxy Zoo has been on the hunt and what they’ve found has proved to be very exciting to the team. Says Keel: “About half of these have gas too highly ionized too far from the nucleus to account for by the nucleus we see (even including far-infrared results to tell how much radiation is being absorbed by dust), so they may be additional, less dramatic instances of the AGN fading over time spans of 100,000 years or so. This large fraction suggests that at least Seyfert nuclei may constantly be brightening and fading over times of a few hundred thousands years (a time span about which we’ve previously had almost no information).”

Their images include those taken with filters that isolate [O III] or Ha emission – even subtracting ordinary starlight. In one such image of UGC 7342, they could trace gas out to twice the estimated size of the Milky Way! This could mean the presence of an AGN. “Starlight doesn’t have enough far-ultraviolet or X-rays to make gas that highly ionized, but an active galactic nucleus does. Furthermore, the ratios of these lines let us estimate how intense this radiation is when it reaches a cloud.” comments Keel. “Even though UGC 7342 is pretty chewed up because of an interaction with at least one companion, the gas motions aren’t as chaotic as they might be – the gas isn’t orbiting retrograde or anything.”

Their research is shedding new light on Voorwerpje mysteries – giving consistencies to ionized clouds located in galaxies which are interacting or merging – and accounting for tidal disturbances. Preliminary findings also show a symmetry as well, where around 50% of the galaxies studied show two ionized clouds on opposite sides.

“Of course, we want to know more. Answers tend to multiply questions. Hubble observations are scheduled, and (with a little luck) X-ray measurements with ESA’s XMM-Newton observatory. We’ve managed to interest some of the people at ASTRON in the Netherlands in using the Westerbork array to examine the cold hydrogen around these galaxies.” says Keel. “In addition, we’re doing new observations of various samples of active and “nonactive” galaxies to look for fainter, and maybe older, gas clouds. Special thanks to everyone who participated in this project, either through the targeted hunt or the complementary forum search for clouds in galaxies not listed as AGN. Stay tuned!”

You can bet we will…

Original Story Source: Zooniverse Blog.

Posted on by Nancy Atkinson

Earth’s First Trojan Asteroid Discovered

2010 TK7 is seen as a speck of light in the center of this image, which is the addition of three individual exposures taken with the MegaCam camera at CFHT. The telescope was tracking the motion of the asteroid, leading to the image of the stars to be trailed. With three exposures added, stars end up looking like a broken trail. Credit: C. Veillet, Canada-France-Hawaii Telescope.

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The first known “Trojan” asteroid in Earth’s orbit has been discovered. A Trojan asteroid shares an orbit with a larger planet or moon, but does not collide with it because it orbits around one of two Lagrangian points. Trojans sharing an orbit with Earth have been predicted but never found until now. Astronomers analyzing data from the asteroid-hunting WISE telescope – which ceased operations in February 2011 – found the asteroid, named 2010 TK7, and followup observations with the Canada-France-Hawaii Telescope on Mauna Kea in Hawaii confirmed the discovery and the object’s stealthy orbit.

In our solar system, we know of Trojans that share orbits with Neptune, Mars and Jupiter. Two of Saturn’s moons share orbits with Trojans. Astronomers have known that Earth Trojans would be difficult to find because they are relatively small and appear near the sun from Earth’s point of view.

But 2010 TK7 proves that Trojans associated to Earth can be found, and astronomers predict that since one has been found, perhaps they’ll find more, as we’ll learn more about their dynamics and characteristics of their population from this first one.

“These asteroids dwell mostly in the daylight, making them very hard to see,” said Martin Connors of Athabasca University in Canada, lead author of a new paper on the discovery in the July 28 issue of the journal Nature. “But we finally found one, because the object has an unusual orbit that takes it farther away from the sun than what is typical for Trojans. WISE was a game-changer, giving us a point of view difficult to have at Earth’s surface.”

The animation below shows the orbit of 2010 TK7 (green dots).

The asteroid is roughly 1,000 feet (300 meters) in diameter. It has an unusual orbit that traces a complex motion near the L4 point. However, the asteroid also moves above and below the plane. The object is about 50 million miles (80 million kilometers) from Earth. The asteroid’s orbit is well-defined and for at least the next 100 years, it will not come closer to Earth than 15 million miles (24 million kilometers).

“It’s as though Earth is playing follow the leader,” said Amy Mainzer, the principal investigator of WISE’s extended mission called NEOWISE that looked especially for Near Earth Object “Earth always is chasing this asteroid around.”

Asteroid 2010 TK7 is circled in green, in this single frame taken by NASA's Wide-field Infrared Survey Explorer, or WISE. Image credit: NASA/JPL-Caltech/UCLA

A handful of other asteroids also have orbits similar to Earth. Such objects could make excellent candidates for future robotic or human exploration. Asteroid 2010 TK7 is not a good target because it travels too far above and below the plane of Earth’s orbit, which would require large amounts of fuel to reach it.

“This observation illustrates why NASA’s NEO Observation program funded the mission enhancement to process data collected by WISE,” said Lindley Johnson, NEOWISE program executive at NASA Headquarters in Washington. “We believed there was great potential to find objects in near-Earth space that had not been seen before.”

The WISE telescope scanned the entire sky in infrared light from January 2010 to February 2011. The NEOWISE project observed more than 155,000 asteroids in the main belt between Mars and Jupiter, and more than 500 NEOs, discovering 132 that were previously unknown.

Sources: Canada-France-Hawaii Telescope, NASA

Posted on by Jason Major

Make iPhone Astrophotography Easier With The AstroClip!

The AstroClip™ is a simple mount that attaches your iPhone onto any telescope. Credit: Matthew Geyster.

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They say necessity is the mother of invention, and if you’ve ever tried to take a picture through a telescope with your iPhone you’ll understand the necessity behind this invention: the AstroClip, an ingenious bit of injection-molded awesomeness that mounts an iPhone 4 onto any standard 1.25″ telescope eyepiece, keeping it stable and centered with the camera lens. I think this is a great idea and would certainly get one… that is, if it actually becomes a reality.

The AstroClip is designed to be very minimal while still being fully functional.

Invented by Boston designer Matthew Geyster, the AstroClip (patent pending) is still in development stage right now, awaiting the funding to go into production. Injection molding is a “simple but very expensive” process and in order to get the AstroClip produced Geyster has put his project up on Kickstarter, a web site that lets people pitch their great ideas that need funding and gives them a timeline to gather pledges.

If the AstroClip project can accumulate $15,000 in pledges by September 3, it will go into production. At the time of this writing there are 38 days left until then and it’s only 10% toward its goal. I’m hoping that drawing some more attention to this cool idea will help it along!

By becoming a “backer” you can pledge in several denomination categories, ranging from $1 or more to $500 or more. Each category above $25 comes with a “reward” of some sort… these are all listed on the project page.

I think Matthew has a great concept here. The camera on the iPhone 4 is very good and could take some great shots of the Moon and other astronomical objects, were it to just have a secure mount on a telescope lens. I’ve tried to do it without a mount before and really, it’s not easy.

Moon image taken with an iPhone and AstroClip

“The AstroClip is designed to be very minimal, while still being fully functional. The clip is very simple and rigid to hold your iPhone 4 steady and securely for the perfect shot. I also added the three adjustment screws that look like they’re meant to be on a telescope. With the simplicity and functionality of the AstroClip you will be taking great photos of outer space in no time at all.”

– Matthew Geyster

Honestly, I have no connection personally with this project or with Matthew… I just think this is something that would be very popular with iPhone users and astronomy enthusiasts. (I don’t even have a telescope… the light pollution in my city is pretty bad.) I just liked the idea so much I wanted to help support it however I could, and Universe Today seemed the perfect place to call attention to it!

If it proceeds the AstroClip will be entirely produced in the USA. Check it out on Kickstarter by clicking the image above or visit theastroclip.com.

Best of luck to a great idea!

All images and video © Matthew Geyster. Universe Today is not endorsing or otherwise officially supporting this project, all opinions of awesomeness are my own and all product claims are made by the product designer.

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Jason Major is a graphic designer, photo enthusiast and space blogger. Visit his websiteLights in the Dark and follow him on Twitter @JPMajor or on Facebook for the most up-to-date astronomy news and images!

Posted on by Jon Voisey

Applying the Titius-Bode Rule to Exoplanet Systems

55 Cancri. Image credit: NASA/JPL

One of the key methods employed in the practice of the sciences is the search for patterns. Their discovery often hints at something important to which we should pay attention if we want to understand a principle. This can be from simple things like the cycles of the sky throughout the year that trace out our motion in the solar system to the patterns of spectral lines that allow astronomers to measure the universe. Back on our solar system scale, one such apparent pattern that stood steadfast until 1846, was the Titius-Bode rule. This rule noted that the distance of the planets from the sun seemed to follow a pattern described by the equation a = 0.4 + 0.3 × 2n where n was the planet number in order of distance from the Sun. This pattern held very well for the first 7 planets, so long as one included the asteroid Ceres, or the asteroid belt itself, as planet #5. Yet the discovery of Neptune and Pluto discredited this pattern as a mere coincidence, mathematical happenstance and numerology, as the Titius-Bode rule severely underpredicted their distances.

Some still wonder if there wasn’t something more to the rule and orbital resonances didn’t have some sort of subtle effect that was being overlooked and made the rule more of a law, at least for innermost planets. With the rapid discovery of planets around other stars, astronomers are once again looking to see if there might just be some sort of truth to this pattern.

One of the most well populated and well studied exo-planetary systems is 55 Cancri. In 2008, a paper was published in the Mexican Journal of Astronomy and Astrophysics attempting to apply the Titius-Bode rule to this system. In that study, the classical rule could not fit, but, from the five planets known at the time, the researchers were able to fit a similar exponential function to the system. With their fit, they found that, much like our own solar system, there was a “missing planet” for what should be the 5th from the parent star. The fit predicted it should lie at a distance of roughly two AU. However, since the paper was published, the orbital characteristics of the system have been revised significantly, throwing off the predictions of the 2008 study.

However, another paper was recently written, updating the fit for the 55 Cnc system. This time, to make the fit work well, the author was forced to assume the possibility of four undiscovered planets. If they were to exist, one of them should exist at a distance of 1.5 AU which, for that system may place it in the habitable zone.

But what of other planetary systems? Presently, there have been few other systems that are sufficiently explored to begin to explore such potential relations. One paper, released in 2010, noted that, at that time, only 15 systems were known with three or more planets. While some appeared, superficially, to have some sort of patterning, the authors declined to speculate on whether or not there was any deeper meaning since, with so little data, a line would be quite easy to fit.

So for now, it’s another game of patience as astronomers continue probing more systems and discovering more planets. If, at some point, a planet were discovered that was predicted by a Titius-Bode relation, it would support the underlying principle that something was sorting the planets in a regular manner. But then again, that’s what they said when Ceres and Neptune were discovered.

Posted on by Nancy Atkinson

New Image Triples Your Galaxy Fun

The Leo Triplet. Credit: ESO/INAF-VST/OmegaCAM. Acknowledgement: OmegaCen/Astro-WISE/Kapteyn Institute

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Here’s a brand new, magnificent look at the Leo Triplet — a group of interacting galaxies about 35 million light-years from Earth. This wide field of view comes courtesy of the VLT Survey Telescope (VST) at the Paranal Observatory. It has a field of view twice as broad as the full Moon — which is unusual for a big telescope – and the FOV is wide enough to frame all three members of the group in a single picture. But there’s also a great new view of galaxies in the background, as the VST also brings to light large numbers of fainter and more distant galaxies, some through the wonders of microlensing.

Microlensing is a gravitational lensing phenomenon where the presence of a dim but massive object can be inferred from the effect of its gravity on light coming from a more distant star. If, due to a chance alignment, the dim object passes sufficiently close to our line of sight to the more distant star, its gravitational field bends the light coming from the background star. This can lead to a measurable increase in the background star’s brightness. As microlensing events rely on rare chance alignments, they are usually found by large surveys that can observe great numbers of potential background stars.

One of the science goals of the VST is to search for much fainter objects in the Milky Way, such as brown dwarf stars, planets, neutron stars and black holes, and microlensing is helpful in finding these elusive objects.

All three of the big, main galaxies seen here are spirals like our own Milky Way galaxy, even though this may not be immediately obvious in this image because their discs are tilted at different angles to our line of sight. NGC 3628, left, is seen edge-on, while the Messier objects M 65 (upper right) and M 66 (lower right), on the other hand, are inclined enough to make their spiral arms visible.

Get more information and see a larger version of this image at the ESO website.

Posted on by Nancy Atkinson

Enceladus Rains Water on Saturn

At least four distinct plumes of water ice spew out from the south polar region of Saturn's moon Enceladus. Credit: NASA/JPL/Space Science Institute

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It’s raining on Saturn! Well, kind of. Actually, not really. But there’s some really cool news about Saturn, Enceladus and water – great topics, all. The bubbly water shooting from the moon Enceladus is responsible for the “mystery” water that was found in Saturn’s upper atmosphere several years ago. Observations with the Herschel space observatory has shown that water ice from geysers on Enceladus forms a giant ring of water vapor around Saturn.

Astronomers from the ESA’s Infrared Observatory discovered the presence of trace amounts of water in Saturn’s atmosphere back in 1997, but couldn’t really find an explanation for why it was there and how it got there. Water vapor can’t be seen in visible light, but Herschel’s infrared vision was able to track down the source of the water vapor.

Enceladus expels around 250 kg of water vapor every second, through a collection of jets from the south polar region known as the Tiger Stripes because of their distinctive surface markings. Much of the ice ends up in orbit around Saturn, creating the hazy E ring in which Enceladus resides.

But a small amount reaches Saturn – about 3% to 5% of Enceladus’s ejected water ends up on the home planet of Saturn.

Phil Plait, The Bad Astronomer figured out that a decent rain shower on Earth is 7,000,000,000,000 times heavier than the rainfall on Saturn. So, not a lot of water makes it to Saturn.

But the fact that a moon is having an effect on its planet is unprecedented, as far as we know.

“There is no analogy to this behaviour on Earth,” said Paul Hartogh, Max-Planck-Institut für Sonnensystemforschung, in Germany, who led the collaboration on the analysis of these results. “No significant quantities of water enter our atmosphere from space. This is unique to Saturn.”

The running theory is that Enceladus has a liquid subsurface ocean of Perrier-like bubbly (and maybe salty) water. No one knows yet how much water lies beneath the moon’s surface, but it is thought that the pressure from the rock and ice layers above combined with heat from within force the water up through the Tiger Stripes. When this water reaches the surface it instantly freezes, sending plumes of ice particles hundreds of miles into space.

The total width of the torus is more than 10 times the radius of Saturn, yet it is only about one Saturn radius thick. Enceladus orbits the planet at a distance of about four Saturn radii, replenishing the torus with its jets of water.

The water in Saturn’s upper atmosphere is ultimately transported to lower levels, where it condenses. But scientists say the amounts are so tiny that the resulting clouds are not observable.

Again, despite its enormous size, this torus has it has escaped detection until now because of how water vapor is transparent to visible light but not at the infrared wavelengths Herschel was designed to see.

“Herschel has proved its worth again. These are observations that only Herschel can make,” says Göran Pilbratt, ESA Herschel Project Scientist. “ESA’s Infrared Space Observatory found the water vapour in Saturn’s atmosphere. Then NASA/ESA’s Cassini/Huygens mission found the jets of Enceladus. Now Herschel has shown how to fit all these observations together.”

Read the team’s paper here.

Source: ESA