A ring of sunshine will blaze above parts of Africa on Thursday as the moon glides between the sun and Earth. The solar spectacle is called an annular eclipse, and sometimes referred to as a “ring of fire” eclipse.
Unlike its better-known relative the total solar eclipse, an annular eclipse occurs when the moon does not completely blot out the sun. For viewers on the ground, instead of witnessing a white halo they will see red slivers of sunlight shining around the moon’s dark silhouette.
“If they look up with protective eyewear they are going to see this strange ring in the sky, more spectacularly they will see these circular shadows,” said C. Alex Young, a solar astrophysicist from NASA. “It’s a cool event, the shadows are kind of eerie.”
The reason every eclipse isn’t a total solar eclipse has to do with the moon’s elliptical orbit. At some points along its journey it is closer to Earth and at some points it is farther away.
“It’s that sweet spot when it’s just right in between the two that you get the total eclipse,” said Dr. Young. “This is not exactly the sweet spot, it’s a little too far away.”
An annular eclipse happens about once every 18 months. Thursday’s event will be visible from Gabon, the Republic of Congo, the Democratic Republic of Congo, Tanzania, Mozambique and Madagascar. The peak will begin around 9 or 10 a.m. local time, depending on location, and the “ring” will last for about three minutes. Nearby countries outside of the 100-mile wide path will still see partial eclipses.
Dr. Young said that although 95 percent of the sun will be blocked out, anyone who is in a position to watch the event should get some special solar eclipse glasses so they do not harm their eyes.
For the rest of the world, you’ll still be able to watch via livestream from Slooh Community Observatory, a network of telescopes pointed to the sky. Their broadcast will begin around 2:45 a.m. Eastern time.
Jay Pasachoff, an eclipse chaser and astronomer at Williams College in Massachusetts, will have a front-row seat to the celestial show.
He and some of his colleagues have traveled to Réunion, a remote island in the Indian Ocean east of Madagascar, in order to see it and photograph the peak. Dr. Pasachoff studies the effects that solar eclipses have on temperature and air pressure.
Annular eclipses don’t provide researchers with as much interesting science as total eclipses, so he plans to use the event as a practice-run for the total solar eclipse that will cross the United States in August next year. Still, Dr. Pasachoff said he is excited to bask in the strange light of the annular eclipse.
“The sky looked perfectly ordinary when I arrived, but tomorrow at the same time the moon will be blocking out most of the sun from the same location,” he said. “It’s intellectually rewarding to see the clockwork of the universe.”
The next annular eclipse will be in February over Chile.