This cloud pattern is a common sight over the northwestern Pacific. Classified as low-level clouds—occurring below 6,500 feet (1,980 meters)—stratocumulus clouds produce little to no precipitation. From the ground they look like a flat layer of clumpy grey clouds. (See more pictures of clouds.)
Photograph courtesy NASA
It's official: barred spiral galaxy NGC 6872 is king of the (galactic) hill. An international team of astronomers has confirmed that NGC 6872 (pictured), long thought to be one of the largest stellar systems in the universe, is indeed the biggest known spiral galaxy.
Located in the southern constellation Pavo, 212 million light-years from Earth, this newly crowned behemoth stretches 522,000 light-years from one end to the other.
Boeing technicians, swathed in clean-room suits, check the first of NASA's next generation satellites being deployed to act as relays between scientific instruments orbiting Earth and controllers on the ground, in an image released January 11. (Learn about satellites and space junk.)
Technicians will pack the TDRS-K—outfitted with new solar panels to provide more power than previous satellites in NASA's space fleet—into a vehicle nose cone to protect it during its flight aboard an Atlas V rocket. (Learn about expendable launch vehicles.)
Photograph by Michael Brown, Reuters
Rock Art at Night
This image of Native American petroglyphs, or rock art, shot against the Milky Way, was taken in California's eastern Sierra Nevada on January 14.
Petroglyphs—one of many forms of rock art—are created by scraping, rubbing, or chiseling designs into the patina coating desert rocks. Depending on the conditions surrounding a piece of rock art, these designs can endure for hundreds to thousands of years. (Watch a video about Arizona's rock art.)
Erosion and natural processes, such as plant growth, can fade or destroy the designs. They can also fall victim to vandalism and theft.
Beijing hit a dubious milestone on January 12, when the U.S. embassy located in the Chinese city recorded an Air Quality Index—a scale used by the U.S. Environmental Protection Agency to measure air pollution—of 755. According to news reports, this was the highest level recorded since the embassy began tracking air pollution in 2008.
In this satellite image, taken January 14, grey-brown streaks of pollution hover over Beijing (center), and mar the bright white spots indicating snowfall.
Image courtesy Jeff Schmaltz, MODIS/NASA
The sun kicked off the new year by throwing a tantrum of sorts, blasting six eruptive prominences—huge loops of plasma that can escape and give rise to coronal mass ejections—from its surface.
This image, taken by a pair of satellites collectively called STEREO and released January 14, captured the roiling solar activity in extreme UV light.
The sun experiences cycles of activity that last for around 11 years. The most recent quiet period, with a drop in the number of sun spots and diminished solar flare activity, lasted three years beginning in 2008. But things started to pick up again in 2011, and astronomers believe the sun is heading into a period of maximum activity in 2013.
A school of fish clump into a ball to guard against predators. The 50 megapixel panorama was taken in October 2009 near the Galapagos Islands. It is made up of 19 individual photographs stitched together.
Week's Best Space Pictures: Hubble's Birthday Portrait
Astronauts spy an approaching spacecraft and satellites capture a cyclone in this week's best space pictures.
Rarely Observed 'Quadruple' Rainbow Isn't What it Seems
A combination of reflections gave birth to the four rainbows captured in a picture by a woman in Long Island.