A total solar eclipse gives scientists a rare opportunity to study the lower regions of the Sun’s corona. These observations can help us understand solar activity, as well as the unexpectedly high temperatures in the corona. Image Credit: S. Habbal, M. Druckmüller and P. Aniol
Q&A: What Happens During a Total Eclipse?
It might be the hottest event of the summer: On Monday, the U.S. will see the first solar eclipse visible across both coasts in nearly a century.
The path of totality — where the view of the Sun will be totally blocked by the Moon’s shadow — will cross from Oregon to South Carolina. The event has turned small towns like Twin Falls, Idaho, and Madras, Oregon, into prime vacation destinations. NASA is hosting events in a number of these locations, as well as encouraging teachers to share science with their students.
Jim Lux, a telecommunications specialist at NASA’s Jet Propulsion Laboratory in Pasadena, California, has traveled far and wide to view total eclipses in the past. Below, he describes what makes them unique experiences.
Q: What happens during a total eclipse that makes it so special?
A: Words don’t describe it — it’s better than any words. Pictures don’t do it justice. Particularly if the corona is right, you get a dark sky with stars and planets and a black hole punched out of it. It’s not super dark like in the middle of the night. The temperature drops and it gets cold.
When the Sun is about half-covered, it’s a crescent, and any shadows form little crescent images everywhere. When you see that, you know totality is close.
You see shadow bands on the ground. These are a couple feet wide, and they move faster than you can run. If you’re sitting next to a pool and see ripples moving on the bottom, it’s a lot like that.
Right before totality, you might see a diamond ring effect, like a lens flare bursting from the remaining edge of the Sun.
Q: Is it eerie?
A: There’s a slightly creepy aspect to the whole thing. There’s no cue saying totality will end, so you’re staring up, waiting for a piece of the Sun to become clear again. It’s the feeling of being in a dark room and thinking, “When I flip the switch, what if the lights don’t go on?”
Q: How many eclipses have you seen so far?
A: I’ve seen three. In 1991, I drove down with my wife to La Paz in Baja California to see one that lasted seven minutes, the longest in a century. In 1994, we went to Puerto Iguazu, where Argentina and Paraguay come together, and watched the eclipse over Iguazu Falls. In 1999, we went to Salzburg, Austria.
That was a broad range of locations: We went from camping in the desert, to the South American jungle, to a nice hotel in Salzburg. For this eclipse, we’re going to eastern Oregon.
Q: What was it like seeing an eclipse in the jungle?
A: The sound changed as it got dark. You hear the same things that happen in the evening: Crickets started up. Cicadas have that buzz when it’s hot during the day, and suddenly go “chirp chirp” when it gets dark. All the transitions at sunset are happening at an odd time of day.
Q: How do people react to a total eclipse?
A: Everyone has all these plans for experiments and photography. They throw all those plans out as soon as totality starts because it’s so cool watching it.
People throw parties during the eclipse. In ’99, it was pouring rain in England; we saw footage of all these people at Stonehenge standing in a soggy field.
In Argentina, intercity buses were driving past the falls at the time of the eclipse, and tourists poured out of them. Then a few minutes later, when it was over, they all poured back in and took off.
source: NASA – Jet Propulsion Laboratory – California Institute of Technology