There is an excellent article at fivethirtyeight.com summarizing how the upcoming solar eclipse is huge opportunity for space weather researchers. During this time, the Moon will eclipse the Sun, and the solar corona will be observable. The corona is the Sun’s atmosphere, which extends far away from the Sun’s surface. It is where many interesting space weather phenomena originate- including the acceleration of the fast solar wind. The short eclipse period will give researches a short but critical window over which to learn more about how the corona behaves.
The corona is not easy to observe. Under normal conditions, it is completely washed out by the light of the sun- it’s like trying to see the distant light of a cell phone screen which is directly adjacent to a headlight. In research, tools known as coronagraphs are used. These are telescopes with fixed occulting disks to block out the light of the Sun, allowing us to observe the corona. An example is the LASCO coronagraph aboard the SOHO satellite. You’ll notice that the occulting disk is very large- much larger than the radius of the Sun. This is to prevent visual artifacts that would otherwise ruin the image. During the eclipse, the Moon covers up much less of the corona than an occulting disk but does not suffer from light artifacts because the moon is very distant compared to the observer. Therefore, the eclipse gives us perfect conditions to see the solar atmosphere.
While I won’t be making observations of the corona, I will be on a short trip to make sure that I don’t miss the eclipse. I’ll share pictures and video here when I return!