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

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

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.

For more information about the eclipse, go to:


For more information about teaching science with the eclipse,
go to:


News Media Contact

Andrew Good
Jet Propulsion Laboratory, Pasadena, Calif.