Nasa Cassini Image: Surface of Titan Sea, Ligeia Mare, is mirror smooth

This false-colour image of the surface of Titan was made using radar measurements made by NASA's Cassini spacecraft. 

The spacecraft revealed that the surface of Ligeia Mare, Titan's second largest lake, is unusually still, most likely due to a lack of winds at the time of observation. 

Credit: Howard Zebker 

New radar measurements of an enormous sea on Titan offer insights into the weather patterns and landscape composition of the Saturn moon. 

The measurements, made in 2013 by NASA's Cassini spacecraft, reveal that the surface of Ligeia Mare, Titan's second largest sea, possesses a mirror-like smoothness, possibly due to a lack of winds.

"If you could look out on this sea, it would be really still. It would just be a totally glassy surface," said Howard Zebker, professor of geophysics and of electrical engineering at Stanford who is the lead author of a new study detailing the research.

Howard Zebker

The findings, recently published online in Geophysical Research Letters, also indicate that the solid terrain surrounding the sea is likely made of solid organic materials and not frozen water.

Saturn's second largest moon, Titan has a dense, planet-like atmosphere and large seas made of methane and ethane.

Measuring roughly 260 miles (420 km) by 217 miles (350 km), Ligeia Mare is larger than Lake Superior on Earth.

"Titan is the best analog that we have in the solar system to a body like the Earth because it is the only other body that we know of that has a complex cycle of solid, liquid, and gas constituents," Zebker said.

Titan's thick cloud cover makes it difficult for Cassini to obtain clear optical images of its surface, so scientists must rely on radar, which can see through the clouds, instead of a camera.

To paint a radar picture of Ligeia Mare, Cassini bounced radio waves off the sea's surface and then analyzed the echo.

The strength of the reflected signal indicated how much wave action was happening on the sea. To understand why, Zebker said, imagine sunlight reflecting off of a lake on Earth.

"If the lake were really flat, it would act as a perfect mirror and you would have an extremely bright image of the sun," he said.

"But if you ruffle up the surface of the sea, the light gets scattered in a lot of directions, and the reflection would be much dimmer. We did the same thing with radar on Titan."

The radar measurements suggest the surface of Ligeia Mare is eerily still. "Cassini's radar sensitivity in this experiment is one millimeter, so that means if there are waves on Ligeia Mare, they're smaller than one millimeter. That's really, really smooth," Zebker said.

One possible explanation for the sea's calmness is that no winds happened to be blowing across that region of the moon when Cassini made its flyby.

Another possibility is that a thin layer of some material is suppressing wave action. "For example, on Earth, if you put oil on top of a sea, you suppress a lot of small waves," Zebker said.

Cassini also measured microwave radiation emitted by the materials that make up Titan's surface.

By analyzing those measurements, and accounting for factors such as temperature and pressure, Zebker's team confirmed previous findings that the terrain around Ligeia Mare is composed of solid organic material, likely the same methane and ethane that make up the sea.

"Like water on Earth, methane on Titan can exists as a solid, a liquid, and a gas all at once," Zebker said.

Titan's similarities to Earth make it a good model for our own planet's early evolution, Zebker said. "Titan is different in the details from Earth, but because there is global circulation happening, the big picture is the same," he added.

"Seeing something in two very different environments could help reveal the overall guiding principles for the evolution of planetary bodies, and help explain why Earth developed life and Titan didn't."

More Information: "Surface of Ligeia Mare, Titan, from Cassini altimeter and radiometer analysis" H.Zebler et al.: 30 JAN 2014 - DOI: 10.1002/2013GL058877

James Webb Space Telescope JWST: Mirror Inspection

Technicians and scientists check out one of the Webb telescope's first two flight mirrors on Sept. 19, 2012 in the clean room at NASA's Goddard Space Flight Center in Greenbelt, Md.

The mirrors are going through receiving and inspection and will then be stored in the Goddard clean room until engineers are ready to assemble them onto the telescope's backplane structure that will support them.

One of the Webb's science goals is to look back through time to when galaxies were young. To see such far-off and faint objects, Webb needs a large mirror.

A telescope's sensitivity, or how much detail it can see, is directly related to the size of the mirror area that collects light from the objects being observed.

A larger area collects more light, just like a larger bucket collects more water in a rain shower than a small one.

Image Credit: NASA.

Interactive Mirror technology: New York Times

Information is everywhere — in the world, in your home, everywhere. In today’s pair of videos from my visit to The New York Times Co.’s R&D Lab, Brian House, The Times Co.’s Creative Technologist for R&D, demonstrates the Lab’s, reflection of that idea — in the form of a data-bearing mirror.

The device (working name: “the magic mirror”) uses Microsoft’s Kinect motion-sensing technology to read physical cues from its user; it uses voice recognition technology to detect verbal cues. (In the videos, you’ll hear House talk to the mirror, Snow White-style.) The mirror also uses the the Times’ powerful APIs to serve up information on-demand.

The device, within its notional home, would replace the standard bathroom mirror. And like the R&D Lab’s screen-topped table, it’s all about bringing a new kind of intimacy to the news experience. You can use it, say, to browse Times headlines, or watch Times videos, while you’re brushing your teeth.


You can use it to schedule events on your personal calendar, or to shop online, or to exchange messages — from the classic “buy milk” on up — with other members of your household.

While the mirror is capable of serving (relatively) traditional forms of content — individual articles, videos, etc. — via its screen functionality, even more striking is its experimentation with information that has, directly, very little to do with the Times itself.

In exploring the realms of health and commerce alongside more standard editorial content, the Times Co. is hinting at the products we might see when news organizations expand their scope beyond the news itself.

Essentially, the mirror fuses news — and, in this case, a highly branded, New York Times experience of the news — with all the other forms of data that we encounter in our daily lives. Again, the “information shadow” idea.

By building a device that is both a screen and a mirror, the R&D Lab can experiment with the ways to combine the personal and the informational in ways that (it hopes!) aren’t intrusive, but rather helpful and, in that, welcome.

This is The New York Times Company acting not just as a curator of information about the wider world, but also as a curator of the information that punctuates, and complicates, and in some sense defines its customers’ personal lives.

Saturn-lookalike galaxy has a mysterious pastNew Scientist

Centuries before telescopes revealed galaxies to us, philosopher Immanuel Kant suggested that "island universes" – agglomerations of stars and gas – existed.

It's a fitting description for the peculiar galaxy pictured right. Consisting of a bright yellow spherical core surrounded by a symmetrical luminous ring of blue-tinged stars, Hoag's object looks like it's doing an impression of the planet Saturn.

This is unlike any other galaxy – and so perplexing to astronomers that it might as well exist in another universe.

"It's one of these weird little objects you point at without fully understanding what they mean," explains François Schweizer of the Carnegie Observatories in Pasadena, California.

He has done his bit in a 60-year struggle to pin down the forces and events that might have created the enigmatic galaxy. Recent observations suggest the core came first and the ring added in later – but the details are still puzzling.

Funhouse mirror
Galaxies come in a variety of shapes, but most fit into one of just a few categories – simple spheroids or ellipses, flattened discs, elegant spirals like the Milky Way or irregularly shaped blobs. But Hoag's object is so bizarre that when astronomer Arthur Hoag first spotted it in 1950, he wasn't even sure it was a galaxy.

Instead he thought it might be a ring-shaped puff of gas given off by a dying star: a type of object called a planetary nebula that is commonly found in the Milky Way. But Hoag himself was unsatisfied with that explanation, noting that the ring was not emitting light at the wavelengths characteristic of the hot gas in such clouds.

He further speculated that the ring could be an optical illusion, the result of a phenomenon called gravitational lensing, in which a foreground galaxy's gravity bends the light of a more distant galaxy, giving it a peculiar shape – like looking at it in a funhouse mirror.

But that explanation failed, too. In 1974, observations of the core of Hoag's object showed it weighs far too little to cause the extreme gravitational lensing needed to turn a background galaxy into a ring.

ESO Image Mirror Nebula: Reflected Glory

The nebula Messier 78 takes centre stage in this image taken with the Wide Field Imager on the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile, while the stars powering the bright display take a backseat. 

The brilliant starlight ricochets off dust particles in the nebula, illuminating it with scattered blue light. Igor Chekalin was the overall winner of ESO’s Hidden Treasures 2010 astrophotography competition with his image of this stunning object.

Messier 78 is a fine example of a reflection nebula. The ultraviolet radiation from the stars that illuminate it is not intense enough to ionise the gas to make it glow — its dust particles simply reflect the starlight that falls on them. Despite this, Messier 78 can easily be observed with a small telescope, being one of the brightest reflection nebulae in the sky. It lies about 1350 light-years away in the constellation of Orion (The Hunter) and can be found northeast of the easternmost star of Orion’s belt.

This new image of Messier 78 from the MPG/ESO 2.2-metre telescope at the La Silla Observatory is based on data selected by Igor Chekalin in his winning entry to the Hidden Treasures competition [1].

The pale blue tint seen in the nebula in this picture is an accurate representation of its dominant colour. Blue hues are commonly seen in reflection nebulae because of the way the starlight is scattered by the tiny dust particles that they contain: the shorter wavelength of blue light is scattered more efficiently than the longer wavelength red light.

This image contains many other striking features apart from the glowing nebula. A thick band of obscuring dust stretches across the image from the upper left to the lower right, blocking the light from background stars.

In the bottom right corner, many curious pink structures are also visible, which are created by jets of material being ejected from stars that have recently formed and are still buried deep in dust clouds.


ESO - eso1105 - Reflected Glory

NASA Astronaut Bone is the Man in the Mirror (Z1 Solar Panel Truss)

Images in the Solar Panel Mirrors may appear distorted in Space.