NATIONAL GEOGRAPHIC'S BEST SPACE PICTURES THIS WEEK XIX

Week's Best Space Pictures: Galaxies Stretch, Stars Tilt, and Mars Beckons
By Dan Vergano, National Geographic News, 1 August 2014.

Secrets of a frozen moon, gravity playing tricks on galaxies, and the watery past of a desert world are spotlighted in this week's best space pictures.

1. Mass Map of Galaxy Cluster

A massive galaxy cluster sprawls across the sky in this July 24 Hubble Space Telescope image.

Filled with stars, the galaxy cluster, dubbed MCS J0416.1-2403, weighs in at 160 trillion times more than the sun. It is one of six such clusters under study by the space telescope.

The gravitational pull of the cluster is so intense that it bends light from its galaxies, blurring and elongating their appearance slightly, a gravitational "lens effect" that magnifies their appearance.

(Image acknowledgement: Mathilde Jauzac (Durham University, UK and Astrophysics & Cosmology Research Unit, South Africa) and Jean-Paul Kneib (École Polytechnique Fédérale de Lausanne, Switzerland)

2. Telescope's Eye Will Pierce the Sky

A giant Thirty Meter Telescope (TMT) telescope, depicted perched atop Mauna Kea in an artist's rendition, will join the ranks of observatories worldwide.

Construction of the telescope has been given the green light and is scheduled to begin later this year. Mauna Kea, renowned for its clear view of the sky, is already home to a dozen large telescopes.

Some 60 mirrors will combine to form the 30-meter (98 feet) main mirror of the TMT. That will make its main mirror more than three times wider than any other visible light telescope on Mauna Kea.

3. What Lies Beneath?

Geysers fume from the south pole of Saturn's mysterious moon, Enceladus, seen in this July 28 peek from NASA's Cassini spacecraft.

A subsurface ocean warmed by the tidal force of Saturn's gravity likely feeds the plumes emanating from the ice-covered moon. NASA scientists now estimate that 101 geysers spring from the four long fractures called "tiger stripes" that line the moon's south pole.

4. Bent Light Reveals Ancient Galaxy

Twisted by gravity, the blue light of an ancient galaxy glimmers beside the red light of a closer galaxy, seen in this July 31 picture.

Some 9.6 billion light-years away, the red galaxy is the most distant one yet seen that uses its gravity to bend light from even more distant stars, creating a gravitational lens effect that magnifies the light from distant objects.

Einstein predicted these gravitational lenses, which are now a favourite of astronomers and allows them to observe distant objects, including the blue galaxy in the picture, which would be otherwise too dim to see.

5. Dust Disks Skewed by Stars

Dueling dust disks are set askew by the gravity of twin stars, shown in this July 30 illustration of the HK Tauri solar system. (See "Astronomers Unravel Secrets of Weirdly Tilted Solar Systems.")

The dust disks surrounding both stars spin in a direction tilted with respect to the rotational direction of their stars. Discovery of the skewed dust disks may help scientists explain how some solar systems develop their tilts.

Most planets are thought to form from such dust disks around stars. Our own solar system spins around the sun in alignment with its equator, but many others don't. Some may have first formed in double star systems like this one.

6. Martian Minerals Hint At Water

Bright rocks piled across the surface of Mars, seen in this July 30 view from space, are water-bearing minerals formed when the red planet was young.

The Mars Reconnaissance Orbiter spacecraft spotted the minerals lining Noctis Labyrinthus, "the labyrinth of the night," a region of the red planet riven by valleys and canyons.

The minerals may date to the late Hesperian epoch roughly 1.8 billion years ago, when Mars was a wetter world.

[Source: National Geographic News. Edited.]