Solar Eclipse

Why August's solar eclipse is your chance to witness one of the greatest mysteries of the universe

Michael Guillen

Scientists are understandably jazzed about the total solar eclipse on Aug. 21. They hope to learn a lot. But you should be excited, too, because the eclipse will pull back the curtains on one of the greatest and deadliest mysteries of the universe: the solar corona.

As a graduate student at Cornell, I came to know Hans Bethe, the brilliant nuclear physicist who in 1967 won the Nobel Prize for figuring out the nuclear fusion reactions that make the sun shine.

Basically, Bethe found that pairs of hydrogen nuclei fuse – like clay balls, they literally stick together – to create zillions of helium nuclei. The magic-like, nuclear transformations are explosive, releasing mind-boggling amounts of energy, as described in Albert Einstein’s famous equation: E = mc2.

It’s that energy – akin to 100 billion H-bombs detonating every second – that lights up the sun’s “photosphere.” That’s the yellow disk kids draw when depicting a sunny day.

During a total eclipse, the moon’s round shadow perfectly blots out the photosphere. The glaring brightness of the photosphere normally blinds us to the corona, which is the sun’s far-fainter, halo-like outer atmosphere. 

Revealing the corona is worthy of great excitement, because the corona is arguably the most mysterious, most turbulent, most unpredictable, most deadly part of the sun.

The corona is where, for some weird reason, the sun’s temperature spikes – from 10,000 degrees to several million degrees Fahrenheit. It’s as if in stepping back from a fire there’s a point where it suddenly feels hotter, not cooler. Hundreds of times hotter! 

For some reasons we don't fully understand – science awaits the next Hans Bethe – the corona is also given to deadly tantrums. Without any warning, it will rise up and fling massive, killer clouds of electrically-charged particles – coronal mass ejections, or CMEs, they’re called – in every direction.

Including our own.

It happened shortly after midnight on September 2, 1859. In what is now called the Carrington Event, a CME hit Earth with the force of 100 million H-bombs, turning night into day by setting the air ablaze. 

“The eastern sky appeared of a blood red color,” reported a woman on South Carolina’s Sullivan’s Island. “The whole island was illuminated. The sea reflected the phenomenon, and no one could look at it without thinking of the passage in the Bible which says, ‘the sea was turned to blood.’ The shells on the beach, reflecting light, resembled coals of fire.”

The surreal brightness fooled birds and many laborers into waking up in the middle of the night, thinking it was morning. Telegraph operators reported seeing “streams of fire” shooting from their equipment and being zapped by giant sparks. 

The National Academy of Sciences has published a chilling report describing what is likely to happen when, not if, the next Carrington-like Event whacks us unexpectedly. The damage worldwide will include: “disruption of the transportation, communication, banking, and finance systems, and government services; the breakdown of the distribution of potable water owing to pump failure; and the loss of perishable foods and medications because of lack of refrigeration.”

“Imagine large cities without power for a week, a month, or a year,” says space physicist Daniel Baker, a co-author of the report. “The losses could be $1 to $2 trillion, and the effects could be felt for years.”

So now you understand why I’m saying you really shouldn’t miss this month’s total solar eclipse. Not only will it (with proper eye protection) give you a rare glimpse at the sun’s normally invisible, enigmatic corona; it will remind you of how easily that wondrous halo can instantly snuff out the mighty, high-tech world we’ve created for ourselves.

Michael Guillen  Ph.D., former Science Editor for ABC News, taught physics at Harvard. His novel, "The Null Prophecy," debuts July 10.