NATIONAL GEOGRAPHIC'S SPACE PICTURES THIS WEEK LXI

Space Pictures This Week: Purple Auroras, Mysterious Moon
By Andrew Fazekas, National Geographic News, 7 June 2013.

Saturn's moon Titan reveals its secrets, purple skies shine over Oregon, and a comet sprinkles dust in this week's best space pictures.

1. Sugary Skies

Looking like mounds of sugar crystals scattered across a black tablecloth, this ultraviolet image, released June 3, showcases the multitude of stars that reside within one of the Milky Way's small companion galaxies.

NASA's Swift satellite has produced the most massive ultraviolet-light survey of the Small Magellanic Cloud (SMC) ever attempted.

The image is the culmination of nearly two days of exposure and was stitched together from 656 individual snapshots spanning 7,000 light-years across. (Related: "Neighbouring Galaxy Caught With Stolen Stars.")

While to Southern Hemisphere sky-watchers this dwarf galaxy looks like a small, hazy patch, the Swift satellite revealed 250,000 individual ultraviolet sources within the SMC.

"With these mosaics, we can study how stars are born and evolve across each galaxy in a single view, something that's very difficult to accomplish for our own galaxy because of our location inside it," NASA's Stefan Immler said in a press statement.

2. Purple Haze

Evergreen trees along the steep slopes of the rim of Oregon's Crater Lake National Park are silhouetted against a sky lit up by vibrant purple auroras on May 31.

"With adrenaline pumping, I raced to the edge of the caldera, set up a time-lapse sequence, and watched northern lights dance until sunrise," said photographer Brad Goldpaint. (See aurora pictures from February and March.)

"The moon rose around 2 a.m. and blanketed the surrounding landscape with a faint glow, adding depth and texture to the shot."

3. "Invisible" Clouds

A recently released satellite photo of what once was one of the largest inland seas in the world, Russia's Aral Sea, shows a mostly dried-up lakebed only a tenth of its original size (seen in black).

The image, taken in March, is partially obscured by wispy, high-altitude cirrus clouds that were previously invisible to satellites.

But NASA's new Landsat Earth-observation satellite can detect the specific wavelength of light that bounces off the ice crystals in cirrus clouds, which helps scientists capture the true atmosphere of the photograph.

For instance, a natural-colour image of the Aral Sea taken on the same day (not pictured) revealed no clouds. (Related photos: "Dried-up Aral Sea Aftermath.")

"Cirrus clouds can be so thin that they won't be visible in a typical image," Pat Scaramuzza, a senior scientist with the U.S. Geological Survey, said in a statement.

4. Mysterious Moon

Previously hidden dark features are revealed in this April 13 image taken by the Cassini spacecraft as it swung by Saturn's largest moon Titan. (Also see "Saturn Moon Has Tropical 'Great Salt Lake,' Methane Marshes.")

The orbiter's near-infrared detectors are able to pull back the curtain of the methane-riddled smog that blankets this mysterious moon, showcasing its detailed topography despite being at a distance of approximately 1.117 million miles (1.797 million kilometres).

5. Cosmic Sprinkler

Like a cosmic sprinkler system, the comet Pan-STARRS appears to spread its fanlike tail, spewing gas and dust into space.

On the night of April 28, on its journey toward the outer solar system, the icy interloper appeared to pose with a ruddy-coloured cloud of gas and dust dubbed Ced 214. (Related: "Pictures: Comet Pan-STARRS Debuts in Southern Hemisphere.")

Although the two cosmic objects may look close together in this image, it's only an optical illusion, since the comet is less than 60 million miles (100 million kilometres) distant - while the nebula lies some 2,700 light-years away.

6. Ashy Peak

Dark ash covering the western slopes of northeastern Russia's Karymsky Volcano lies in stark contrast to late-season snow blanketing the surrounding terrain in this NASA Landsat 8 orbiter snapshot taken May 20 and released June 3.

Karymsky is the most active of many volcanoes that dot the Kamchatkan Peninsula, and is believed to have formed inside a three-mile-wide (five-kilometre-wide) caldera about 12,000 years ago.

[Source: National Geographic News. Edited.]