NATIONAL GEOGRAPHIC'S SPACE PICTURES THIS WEEK LIV

Space Pictures This Week: Green Death Shroud, Airglow
By Jane J. Lee, National Geographic News, 15 April 2013.

Plasma dances across the sun and Earth’s air glows in this week's best space pictures.

1. Weekend Space Weather

The restless star at the centre of our solar system never fails to dazzle, as evidenced by this picture of solar plasma taken March 28 by the Solar Dynamics Observatory.

Guided by the sun's magnetic field, ropes of plasma escape from the star only to be dragged back or twisted around into whorls of light.

Scientists predict 2013 will see a peak in solar activity, and Earthlings got a preview this past weekend when the sun released a mass of plasma and charged particles on April 11. (Related: "Solar Storm Heading Toward Earth.")

The coronal mass ejection hit Earth's atmosphere on April 13, but only resulted in some faint auroras. (See pictures of the best auroras of February and March.)

2. Rock Jumble

The High Resolution Imaging Science Experiment (HiRISE), orbiting the red planet on the Mars Reconnaissance Orbiter, snapped an image of large rocks on the floor of an impact crater in an image released April 10.

The fragmented rocks, greater than three feet (one meter) across, are mixed in with smaller, fine-grained particles. This type of mix is called megabreccia, and usually results from impact events like a meteor hitting a planet.

3. Ghostly Green Shroud

The final death throes of a dying star in the constellation Scutum (the Shield) produce a glowing shroud in this picture released April 10 by the European Southern Observatory. The cloud of gas, called planetary nebula IC 1295, is located 3,300 light-years away.

When stars the size of our sun fade away, they don't go quietly. During the final phase of a star's demise, unstable fusion reactions in its core blow its atmosphere into space. Radiation from the star interacts with the gas, causing the whole thing to glow. (Learn about the life cycle of stars.)

4. Desert Starlight

Photograph by Oshin D. Zakarian, TWAN

The ruins of a desert castle stand guard near the town of Kashan (map), Iran, in a picture taken March 16.

The Milky Way galaxy marches across the sky while airglow - light emanating from Earth's atmosphere - paints the night with pale greens and purples.

Unlike auroras, which occur because charged particles from the sun collide with molecules in Earth's atmosphere, airglow happens when ultraviolet radiation excites molecules 53 to 60 miles (85 to 95 kilometres) up.

When the molecules, most commonly oxygen, return to their "normal" states, they give off energy in the form of light - what we call airglow.

5. Patchwork Fields

Agricultural fields in the Palouse region turn Washington State countryside into a patchwork of grey and tan in this picture released in April by the European Space Agency.

Located in the southeastern part of the Columbia Plateau, Palouse is home to the majority of the state's wheat farms.

[Source: National Geographic News. Edited.]