Best Space Photos of the Week: From Solar Flares to Saturn’s Moons

The sun started this week off with a bang, generating a mid-level solar flare that peaked on January 12. Captured here by NASA's sun-watching satellite the Solar Dynamics Observatory, the event was the first significant flare of the year—but it certainly won't be the last.

Solar flares are bursts of powerful radiation that happen when pent up magnetic energy in the sun's atmosphere is suddenly released. While the number and strength of solar flares in a year varies based on the sun's 11-year activity cycle, even a quiet sun usually produces several flares annually. Earth's atmosphere mostly protects us from the onslaught of radiation, although strong flares can disrupt GPS and communications signals. Flares can also send clouds of solar particles racing into space, and if they hit Earth, the particles can spark brilliant aurora displays.

The hazy green head of Comet Lovejoy (C/2014 Q2) shines against a starry backdrop in an image snapped on January 10 by NASA scientist Bill Cooke. The comet made its closest approach to Earth on January 7 and is now racing toward a close encounter with the sun.

The comet has been getting brighter since the beginning of the new year, as increasing heat from the sun has vaporized its ices, releasing clouds of dust and gases that fluoresce in sunlight. Astronomers tracking Comet Lovejoy's path estimate that it follows a long, highly elliptical orbit around the sun. That means it came from exceptionally far away in the solar system, and it's not expected to return for another 8,000 years.

Lakes provide a variety of benefits to humans, from freshwater supplies to recreational escapes. But Nansi Lake in China’s Shandong province stands out for the high level of human development that shapes its shorelines. A 2013 study estimates that 34 percent of the lake's area is being used for aquaculture and 19 percent has been converted into farms.

This image from NASA's Landsat 8 satellite, released on January 10, shows the lake's unusual shoreline, where the turquoise rectangles of aquaculture ponds give way to emerald farmland. The lake is also an eastern reservoir in a massive project to move water from the Yangtze River into arid northern China. 

From gardening to gecko sex, most of the experiments sent to space are trying to answer a simple question: how does low gravity affect activities that normally happen on Earth? As part of that glorious tradition, the glowing ball seen above is a Russian chemistry experiment on the International Space Station that tests how well we can synthesize polymers in space.

Polymers are molecular chains made up of many repeating units. They can be found in nature as DNA, proteins and cellulose, and scientists have created a growing list of useful synthetic polymers, including nylon, Teflon and Styrofoam. In the weightlessness of space, the chemical reactions that make polymers can be tailored to form shells, like the one seen in this European Space Agency image of the Russian experiment released on January 13.

On January 14, 2005, the European Huygens probe touched down on Saturn's biggest moon, Titan. Released by NASA's Cassini spacecraft, the Roomba-like robot took scads of images as it parachuted down through Titan's orange haze, offering scientists a first detailed glimpse of the icy alien moon. For the probe's tenth anniversary, NASA and ESA re-released this image series taken during the descent, which shows a fish-eye view of the moon's surface from various altitudes.

Huygens transmitted data for only an hour in the frigid floodplain where it landed before its batteries were drained, but the information it collected has been invaluable to astronomers piecing together the workings of the intriguing moon, the only object in the solar system aside from Earth with a thick atmosphere and stable bodies of liquid on its surface. 

Commercial spaceflight hopeful Virgin Galactic took a major hit in October, when its SpaceShipTwo space plane crashed in the Mojave Desert during a test flight, killing a co-pilot and wrecking the only working ship in the fleet. But Virgin Galactic CEO George Whitesides was already working on a second ship, and he was quick to announce plans to have that plane ready for testing by the summer of 2015.

On January 9, Whitesides announced at a conference that Virgin engineers are developing a test program, and on January 15, the company released a behind-the-scenes video of the second SpaceShipTwo being built at the company's Mojave factory. The video still suggests there is still a ways to go before the craft is flight-ready, but Whitesides says test flights will start later this year—and a third SpaceShipTwo will soon begin assembly.

Does "you break it, you bought it" still apply on Mars? This week the Mars rover Curiosity was investigating rocks along the base of Mount Sharp, a mysterious mountain at the center of the rover's landing site, Gale Crater. A particular rock nicknamed "Mojave" caught scientists' eyes because it seems to have a unique crystal structure. Data from Curiosity has so far supported the notion that Gale Crater was once a huge lake, and it's possible the crystals are mineral deposits created as the water evaporated.

However, an initial "mini drill test" on Mojave didn't produce a clean borehole. Instead the rock cracked and dislodged large fragments. While it's unclear whether drilling will continue, the shattered rock may be a boon to geologists: The cracks expose large fresh surfaces unweathered by the harsh Martian conditions, which may help scientists understand the mountain's watery history.