A small NASA telescope was launched into orbit on Thursday on a mission to determine how the sun heats its atmosphere to millions of degrees, sending off rivers of particles that define the boundaries of the solar system.

 

The study is far from academic. Solar activity directly impacts Earth's climate and the space environment beyond the planet's atmosphere. Solar storms can knock out power grids, disrupt radio signals and interfere with communications, navigation and other satellites in orbit.

 

Scientists have been trying to unravel the mechanisms that drive the sun for decades but one fundamental mystery endures: How it manages to release energy from its relatively cool, 10,000 degree Fahrenheit (5,500 degree Celsius) surface into an atmosphere that can reach up to 5 million degrees Fahrenheit (2.8 million Celsius).

 

At its core, the sun is essentially a giant fusion engine that melds hydrogen atoms into helium. As expected, temperatures cool as energy travels outward through the layers. But then in the lower atmosphere, known as the chromosphere, temperatures heat up again.

 

Pictures and data relayed by the Interface Region Imaging Spectrograph, or IRIS, telescope may finally provide some answers about how that happens.

 

The 4-foot (1.2-meter) long, 450-pound (204-kg) observatory will be watching the sun from a vantage point about 400 miles above Earth. It is designed to capture detailed images of light moving from the sun's surface, known as the photosphere, into the chromosphere. Temperatures peak in the sun's outer atmosphere, the corona.

 

IRIS, which cost about $145 million including the launch service, is designed to last for two years.