As the last specks of sunlight disappear and totality commences Aug. 21, we will be able to see something impossible to see otherwise with the naked eye — the sun’s atmosphere.
It’s always up there, but direct visual observation is impossible; after all, the sun produces enough light to outshine anything nearby. However, as the solar disk becomes obscured by the moon, the corona will brilliantly emerge for the bulk of totality.
Steamers of plasma and fingerlike “prominences” will radiate outward around the sun, resembling thousands of strands of hair blowing in the wind. Meanwhile, scientists nationwide will document the spectacle to gain insight into the magnetic field structure of the sun.
The sun’s corona — Latin for “crown” — is a testament to just how incredibly energetic the sun is. Torrents of plasma can be launched millions of miles in any direction as coronal mass ejections, with the resulting flare posing a danger to any space-borne object in its path.
Even the corona itself is volatile, reaching temperatures of several million degrees — far surpassing the sun’s “mild” 11,000-degree surface. At temperatures this high, iron atoms are able to rapidly gain and rid themselves of electrons, subsequently emitting instantaneous bursts of red or green light.
The corona isn’t what makes the sun bright, but it does produce a little bit of natural light of its own, which is why we can see it after the moon covers the disc of the sun. Scientists will be able to identify what elements are present based on the wavelengths at which they radiate.
The patterns you witness in the corona during the eclipse are a remarkably good indicator of the behavior of the magnetic field — outward-streaming “flux” will appear as lines zipping away in the solar wind, whereas a few returning coronal loops will connect the poles to the equator.
Large eruptions of the sun’s plasma and magnetic field frequently originate from the solar corona. Sunspots, like dark bruises on the sun’s otherwise-bright complexion, occasionally hurl high-energy particles toward Earth. Like enormous volcanic eruptions, the force of these solar explosions is incredible and, if aimed correctly, would be crippling to our modern lives.
The results of a massive, Earth-directed coronal mass ejection could be beautiful but also disastrous; while a nearly worldwide display of the auroral lights could be in the ejection, unprotected power grids would be susceptible to voltage surges and overloads, wiping out much of the electrical grid and grinding the worldwide economy to a halt.
However, there’s no cause for alarm Aug. 21. Instead, get ready to witness something that is truly out of this world.
As NASA put simply, “Even in 2017, there is no available technology to map the magnetic field in the corona at resolutions comparable to those details seen during a total solar eclipse!”