How do the outer reaches of the sun get so hot? That’s one of the questions that NASA has set out to answer by launching a new telescope that will stare into a mysterious zone between the sun’s surface and outer atmosphere.

Material that travels through the region, known as the solar chromosphere, heats up from about 10,000 degrees Fahrenheit (5,500 degrees Celsius) at the sun’s surface to temperatures as high as 3.5 million degrees Fahrenheit (2 million degrees celsius) farther out, according to NASA.

The agency says its IRIS spacecraft, which reached its orbit Thursday evening after taking off from Vandenberg Air Force Base in California, will angle its telescope to study “how solar material moves, gathers energy and heats up” in the chromosphere on its way to the outer atmosphere, the corona.

“IRIS will show the solar chromosphere in more detail than has ever been observed before,” Adrian Daw, deputy project scientist, said in a NASA article ahead of the launch. “My opinion is that we are bound to see something we didn’t expect to see.”

What causes the corona’s intense heat has been “a scientific mystery for more than 50 years,” according to NASA’s Solar System Exploration unit. Information gathered by previous space missions suggests one source could be a magnetic field covering the sun’s surface, the unit says.

Scientists are also interested in the chromosphere because it generates most of the sun’s ultraviolet rays that affect Earth’s climate.

The data gathered by IRIS, which stands for Interface Region Imaging Spectrograph, will add to the work of two other missions that will monitor the sun’s surface and outer atmosphere.

– Homepage image / File, Debbie Zillwood

– CNN