The sun isn't a smooth, contained ball of plasma. It's actually got radiation shooting off it all willy-nilly, all the time. But it's never looked quite as lovely as it does in the image above.
NuSTAR was designed to look at distant black holes, and this is the first time scientists have turned it on our own sun.
"At first I thought the whole idea was crazy," mission principal investigator Fiona Harrison said in a statement. "Why would we have the most sensitive high energy X-ray telescope ever built, designed to peer deep into the universe, look at something in our own back yard?"
But only NuSTAR was powerful enough to capture the faint x-ray emissions of the star, which are seen in green and blue. These high-energy x-rays come from gas heated higher than 3 million degrees.
The sun has been pretty active lately, throwing off lots of radiation. But as it calms in the coming years, NASA scientists hope that NuSTAR will be able to detect theoretical nanoflares -- tiny eruptions of radioactive particles, like smaller versions of the solar storms we can observe, that have never been recorded. From NASA:
Nanoflares, should they exist, may explain why the sun's outer atmosphere, called the corona, is sizzling hot, a mystery called the "coronal heating problem." The corona is, on average, 1.8 million degrees Fahrenheit (1 million degrees Celsius), while the surface of the sun is relatively cooler at 10,800 Fahrenheit (6,000 degrees Celsius). It is like a flame coming out of an ice cube. Nanoflares, in combination with flares, may be sources of the intense heat.
And it's less likely, but NuSTAR could help scientists spot dark matter, too. It's possible that the telescope is sensitive enough to spot particles of dark matter called axions. If they exist (and can be spotted) they'd show up as a spot of x-rays in the center of the star.