NATIONAL GEOGRAPHIC'S BEST SPACE PICTURES THIS WEEK XXV

Week's Best Space Pictures: Moons Ravaged, Auroras Revel, and Astronauts Return
By Jane J. Lee, National Geographic News, 12 September 2014.

Saturn's gravity pillages moonlets, a solar storm births auroras, and space explorers come home in the week's best space pictures.

1. Psychedelic Supernova

The messy remnants of a star's death, a supernova, surges into space in this image released September 10. Located about 7,000 light-years away from Earth, the initial explosion of the star would have been seen from our planet about 3,700 years ago.

Pictures from both the Chandra X-ray Observatory and the XMM-Newton combine to form the most detailed view of this particular supernova yet, seen in the view above. Low-energy x-rays glow in red, medium-energy ones are green, and high-energy x-rays are blue. (See "Scientists Find Remnants of One of Universe's Oldest Stars - And It's Huge.")

2. Homecoming

Russian cosmonaut Oleg Artemiev peers out the window of a Soyuz capsule after landing outside the town of Zhezqazghan, Kazakhstan, on September 11. Artemiev, cosmonaut Alexander Skvortsov, and NASA astronaut Steve Swanson all returned to Earth this week after spending five months on the International Space Station (ISS).

The three men were part of Expedition 40, and they spent part of their time in space helping to run experiments that tested the effects of space radiation and microgravity on proteins, genes, and muscles in the human body.

3. Ghostly Greens

Photograph by Yuichi Takasaka, TWAN

The northern lights flare above Yellowknife in Canada's Northwest Territories. The ghostly green ribbons appear when charged particles blasted off the sun - via coronal mass ejections - splatter against Earth's magnetic field. (See more pictures of auroras.)

4. A Road Less Travelled

We know what the Mars rover Opportunity did this summer: Tracks winding from the west rim of Endeavour Crater chronicle the vehicle's journey across the red planet as the little-rover-that-could makes its way south. (Watch a video of how far Opportunity has driven on Mars.)

Opportunity was originally intended to last for 90 Martian days, or "sols." A sol is slightly longer than a day on Earth. The rover has now been operational for ten years, driving across the red planet investigating, zapping, and analyzing Martian rocks and soil. (See "NASA Celebrates 10-Year Anniversary of Mars Rover.")

5. An Irregular Galaxy

A cosmic oddball in the constellation Leo, galaxy IC 559 stands out among galaxies. It's not a spiral similar to its neighbours, and in fact, IC 559 doesn't seem to sport any sort of regular shape at all.

The image above, released September 8, captures IC 559 in all of its weird, blue glory. But researchers think it might not have always been the odd one out. It could have been a regular spiral galaxy at one time, but gravity from a nearby celestial object may have bent IC 559 completely out of shape.

6. One Ring

Something is happening in one of Saturn's outer rings: SETI researchers studying recent Cassini images of the F-ring noticed that bright spots present in photographs taken 30 years ago by the Voyager mission were missing. Upon further examination, they found that bright points can appear and disappear from this ring over the course of hours to days. (Read about the history of the Voyager missions.)

They think those bright spots are the death throes of little moons - or moonlets - as they collide with other debris in the F-ring. This ring is situated at just the right distance from Saturn such that gravity can stir up debris, forming moons no bigger than a large mountain. Gravity can also pull those mini-moons apart. (See "Saturn Moon Harbours Ocean, Raising Possibility of Life.")

This seesaw between birth and death is what produces these ephemeral bright spots in the F-ring, the researchers speculate.

7. Sacred Night

Photograph by Ladanyi Tamas, TWAN

The Milky Way stretches across the night sky above Mădărăs, a town in the Harghita Mountains in Romania. Historical crosses - the site is considered sacred by the Székely culture - are backlit by the night sky. (See "New Map Locates Milky Way in Neighbourhood of 100,000 Galaxies.")

Photo Gallery by Nicole Werbeck

[Source: National Geographic News. Edited.]