Space Pictures This Week: Red Auroras, Mars Avalanche

Tasmanian Aurora

Photograph courtesy NASA

Multicolored lights dance over the Tasman Sea in a picture of the aurora australis, or southern lights, taken in September from the International Space Station.

Auroras are created when charged solar particles collide with molecules in Earth's atmosphere, infusing the molecules with extra energy that then gets emitted as light. Colors are based on which types of molecules are affected and how high they are in Earth's atmosphere.

(Also see "Aurora Pictures: Rare Northern Lights Seen in U.S. South.")

Published October 28, 2011

Toothy Pac Man

Image courtesy UCLA/Caltech/NASA

The Pac Man Nebula has sprouted teeth, as seen in a new picture from NASA's Wide-field Infrared Survey Explorer, or WISE.

In visible light, the cloud of gas and dust has a smooth triangular "mouth" reminiscent of the classic arcade game character. But the new infrared view shows the nebula's lower jaw lined with pillars of dense material that look like jagged teeth—regions where new stars may be forming.

Published October 28, 2011

Approaching Earth

Photograph courtesy Rolando Ligustri

Comet C/2009 P1, seen from Italy's Cast Observatory on October 15, is approaching Earth.

Comets are balls of rock and ice that grow tails as they approach the sun in the course of their highly elliptical orbits. As comets heat up, gas and dust are expelled and trail behind them. The sun illuminates this trail, causing it to glow, and thereby making it visible in the night sky, given the right conditions.

(See "New Comet Found; May Be Visible From Earth in 2013.")

Published October 28, 2011

Aurora Layers

Photograph courtesy Branislav Beliancin

Curtains of red and green auroras seem to drop from the skies in a picture taken October 25 from Spjelkavik, Norway.

A cloud of charged particles from the sun slammed into Earth Monday, setting off an intense geomagnetic storm that spawned a burst of northern lights seen farther south than normal.

In the U.K., for instance, reports of auroras came in from as far as Ayrshire (map), just south of Glasgow, according to the BBC.

Published October 28, 2011

Martian Avalanche

Image courtesy U. Arizona/NASA

A cloud of dust 600 feet (200 meters) wide is evidence of an avalanche on Mars, as seen in a recently released picture from NASA's Mars Reconnaissance Orbiter.

The satellite's high-resolution camera snapped its first avalanche in action in 2008. Since then the MRO has been searching for them along the steep cliffs of layered deposits around Mars's north pole.

Studying pictures of such events can help scientists figure out if the landslides are being triggered by seasonal climate changes, strong winds, or as yet unknown phenomena on the red planet.

Published October 28, 2011

Moon Quartet

Image courtesy Cassini/ESA/NASA

If you look closely, you can spot four moons in this one picture of the Saturn system recently taken by NASA's Cassini orbiter.

At center, the bright moon Dione stands out against the darker grey of Saturn's largest moon, Titan. The smaller moon Pandora sits to the right, near the edge of part of Saturn's many rings. To the left, the moon Pan appears as a speck within a dark gap in between the rings.

Published October 28, 2011

Satellite's Final Fall

Image courtesy Franhofer FHR/DLR

On October 23 the German research satellite ROSAT (picured on October 20) reentered the atmosphere over the Bay of Bengal, though it's unknown whether any parts of the satellite reached Earth's surface.

"With the reentry of ROSAT, one of the most successful German scientific space missions has been brought to its ultimate conclusion," the German Aerospace Center's Johann-Dietrich Wörner said in a statement.

(See "Another Dead Satellite to Fall to Earth This Weekend.")

Published October 28, 2011

Ice Classes

Image courtesy Jesse Allen and Robert Simmon, EO-1/NASA

In Antarctica, not all ice is created equal: This recently released picture from NASA's Earth Observing-1 satellite shows several different types of ice in a single frame.

So-called fast ice—named because it holds fast to the shore—fills the right side of the image. This ice is very thick and so appears bright white. Near the edges of the fast ice are icebergs, thick hunks of ice saturated with meltwater, which gives them a bluish tinge.

To the left of the frame is pack ice, which is much thinner and so shows more of the underlying seawater, giving the ice a blue-gray hue. In between the pack ice are swirls of newly formed sea ice called frazil and thin sheets known as nilas.

Published October 28, 2011