If you've ever stood beside a roaring fire, you know it can get pretty hot. And if you get too hot, you could just walk away, because the farther you are from a heat source, the cooler it is around you.
But that does not always hold true everywhere.
The surface of the sun is about 6,000 degrees Celsius, but its upper atmosphere is about one million degrees hotter, even though it's farther from the sun's heat-generating core.
Scientist Jeffrey Newmark says it's a mystery.
"What causes this rise? How does the energy transfer from the surface - the cool surface - to this hot outer atmosphere? This is the question that IRIS, the science of IRIS, is going to address," he explained to reporters at a NASA briefing.
Newmark is the program scientist for IRIS, NASA's Interface Region Imaging Spectrograph. It's a small satellite that will observe the way solar material heats up as it rises through the sun's lower atmosphere. IRIS, with its ultraviolet telescope, will provide high-resolution images and even show individual towers of energy released by the sun. It will orbit our Earth as it studies our sun.
NASA scientists say this new mission will yield insights into solar activity that is believed to be linked to power outages here on Earth.
The IRIS mission began Thursday night, when an aircraft flying over the Pacific Ocean released Orbital Sciences' Pegasus XL rocket that carried NASA's newest solar observatory into space.
The mission started 24 hours later than planned. Mission managers had to delay the launch from Vandenberg Air Force Base in California by one day because of a power outage at the base.
Pete Worden, director of NASA's Ames Research Center in California, said in a pre-launch briefing that this twist underscored the importance of the IRIS mission.
"We believe that some - maybe a lot - of power outages actually have a lot to do with solar activity, so the better we can understand the physics going on, the better we can understand that activity, the better that we could potentially predict and mitigate some of these problems," he said.
The sun's ultraviolet emissions are generated in the mysterious interface region. They affect our planet's climate and the space environment near Earth.
Wave of the Future
NASA's Worden says the IRIS mission also shows a new direction for the space agency.
"It demonstrates, I think, the wave of the future that we're going to be doing a lot more with lower-cost, smaller missions, at the same time getting really Earth-shaking science," Worden said. "This is the first mission that will really tell us the detailed physics that's going on at the solar surface and the atmosphere above it."
The $181 million IRIS mission is set to last two years, but scientists say the solar explorer could function much longer.