NATIONAL GEOGRAPHIC'S BEST SPACE PICTURES THIS WEEK VI

Best Space Pictures: Aurora Churns, Saturn Turns, and Starburst Burns
By Dan Vergano, National Geographic News, 2 May2014.

Saturn gazes upon another world, while stars burn and northern lights gleam in the week's best space photos.

1. Sparks Join Aurora

Photograph by Chris Cashwell, National Geographic Your Shot

Sparks fly as an aurora lights up this week's sky in this gorgeous Your Shot view of night-time Alaska.

A solar outburst glancing off the Earth's magnetic field spurs an aurora. With the sun now at the height of its solar cycle, such geomagnetic storms - and northern lights - have happened monthly (see more aurora photos).

2. Saturn's Rings See Uranus

A first-ever view of Uranus as seen from the rings of Saturn, courtesy of the Cassini spacecraft on May 1.

In orbit around the ringed planet, the spacecraft turned to view the nearby ice-blue world in April. The beauty shot of Uranus, the seventh planet from the sun, will help mission scientists calibrate the cameras aboard Cassini.

3. Stellar Lens Magnifies Exploding Stars

Hubble Space Telescope astronomers revealed three supernova stars with explosions magnified by a trick of gravity, reported at the beginning of May.

The explosions aren't any bigger than normal for supernovae - these ones are nicknamed Tiberius, Didius, and Caracalla - but the light from them was brightened by a gravitational "lens."

First predicted by Einstein, the lens effect was created by the massive gravity of galaxies lying between Earth and the exploding stars, which bent and magnified their light. Hubble and other observatories have increasingly turned to Einstein's trick in the last decade to observe stars that would otherwise be too distant to view.

4. Dunes Crawl Across Mars

Winds scrape the dunes of the red planet, seen in an overhead look released April 30 from a camera aboard NASA's Mars Reconnaissance Orbiter.

Planetary scientists carefully watch for landslides and shifts at Nili Patera, one of the most dynamic dunes on Mars. These ripples reveal how winds have sculpted the planet and how the seasons change the face of the nearby world.

5. Starburst Galaxy Burns Bright

Burning bright, the spiral galaxy Messier 61 spins out young stars at an astonishing rate, seen in this April 28 close-up from the Hubble Space Telescope.

Such starburst galaxies burn through vast clouds of gas at their centres, serving as powerful stellar nurseries. At the heart of the galaxy, a supermassive black hole helps power the process, spewing out tell-tale radiation as it devours star stuff. (Read "Star Eater" in National Geographic magazine.)

6. Rover Drills Martian Sandstone

Drill, baby, drill! NASA's Curiosity rover inspects a sandstone slab in this April 25 image.

The rover's third drilling target on the red planet, the slab is nicknamed "Windjana," after a gorge in Western Australia. It is the first sandstone ever drilled on Mars. Previous targets were mudstones formed in ancient lake beds.

Curiosity is on a mission to explore Mount Sharp, located in the heart of a crater on Mars. NASA scientists suggest that a lake once ringed the mountain, and the roving chemistry lab aims to uncover evidence of long-ago habitable conditions there. (Learn more about the Curiosity rover.)

[Source: National Geographic News. Edited.]