The corona is the outermost part of our closest star’s atmosphere, and is hundreds of times hotter than its surface.
Nasa is set to make a major announcement about its first mission “to touch the sun”.
The agency wants to send a spacecraft closer to the sun than ever before, where it will face extreme temperatures and radiation levels.
It will speak about Solar Probe Plus at an event on Wednesday, which will be livestreamed on Nasa Television and the agency’s website from 4pm BST.
The spacecraft, which is set to take off in the summer of 2018, will be tasked with collecting data about the mechanisms that heat the corona, the outermost part of the sun’s atmosphere.
For reasons currently unknown, the corona is hundreds of times hotter than the sun’s surface, with temperatures at 500,000 degrees Celsius or higher.
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