Eclipse Science

Astronomers have been studying the Sun for so long that you might think they know everything there is to know about it. And they do know quite a bit. It’s a hot ball of gas that’s 865,000 miles wide. It’s powered by nuclear reactions deep in its core. And it’s been shining for billions of years, and will keep going for billions of years more.
Yet there are still some mysteries about the Sun. At the top of the list is what heats its outer atmosphere, the corona. Although it’s quite thin, it’s millions of degrees hotter than the surface of the Sun, and scientists aren’t sure why.
The corona most likely is heated by energy from the Sun’s magnetic field. The field creates dark sunspots, powerful explosions, and outbursts of billions of tons of charged particles. Those events impart some energy to the corona, but not nearly enough to account for its temperature.
Solving the mystery requires more observations of the corona, but they’re hard to get. The Sun’s disk is a million times brighter