By Elizabeth Landau, CNN
The sun's outer atmosphere, called the corona, is much hotter than its surface. The atmosphere's temperature rises to millions of degrees, while the surface is only about 5,000 degrees Kelvin - a mysterious contrast, given that the atmosphere is farther from the sun's hot core.
Scientists wanted to find out what energy source could be responsible for the inflated temperatures of the corona, which is where space weather - such as solar flares and coronal mass ejections that can interfere with your GPS - comes from.
Space, it has been said, is big. Really big.
But big enough for two companies that want to mine near-Earth asteroids?
A venture announced Tuesday in California hopes so.
Deep Space Industries says it wants to start sending miniature scout probes, dubbed "Fireflies," on one-way missions to near-Earth asteroids as soon as 2015. Larger probes, "Dragonflies," that will bring back 50- to 100-pound samples from prospective targets could be on their way by 2016, company CEO David Gump told reporters.
Editor's note: Greg Bear is an internationally bestselling science-fiction author of many books, including "Moving Mars," "Darwin's Radio" and "Hull Zero Three." As a freelance journalist, he covered 10 years of the Voyager missions at the Jet Propulsion Laboratory.
Look up at our nearest neighbor, the moon, and you'll see stark evidence of the dangerous neighborhood we live in. The Man in the Moon was sculpted by large-scale events, including many meteor and asteroid impacts.
In 1994, the comet Shoemaker-Levy 9 dove into Jupiter. The result was awesome. The impact caused a brilliant flash, visible in Earth telescopes, and left an ugly dark scar on Jupiter's cold, gaseous surface.
With the recent fly-by of a 1,000-foot-wide asteroid labeled 99942 Apophis, one of a class of space rocks referred to as "near-Earth objects" or "Earth-grazers," scientists have revised their worst estimates of its chances of striking Earth. Current thinking is: We're safe. For the next couple of decades.