How, where and when to see the ‘hybrid’ or annular-total solar eclipse on April 20, 2023
When is the next eclipse? It’s on Thursday, April 20, 2023, but exactly where you are on Earth will determine whether you will be able to see any of the Sun disappear behind the Moon during a rare total solar eclipse.
Thousands of eclipse-chasers from across the globe will descend on Western Australia, Timor Leste and West Papua—on land and in cruise ships and yachts—to experience a rare kind of “hybrid” solar eclipse.
Here’s everything you need to know about the first and the best solar eclipse of 2023:
Where is the April 2023 solar eclipse?
April’s solar eclipse will be visible from Australasia and Southeast Asia. While the entire area will see a partial solar eclipse—including the whole of Australia, Indonesia, Singapore, Malaysia and the Philippines—only from a very narrow swathe of the planet will it be possible to see a total eclipse of the Sun.
Where is the total solar eclipse?
A narrow path of totality just 25 miles wide will stretch from near the remote Kerguelen Islands in the Indian Ocean to the Pacific Ocean. Along the way it will graze the coast of Western Australia and move through Timor Leste and West Papua.
Here’s how long totality will last at these key viewing locations in this narrow and particularly remote path of totality:
- Exmouth, North West Cape, Western Australia: 60 seconds at 11:29 AWST
- Barrow Island, Western Australia: 64 seconds at 11:34 AWST
- Wells Beach, Montebello Islands, Western Australia: 56 seconds at 11:34 a.m. AWST
- Scott Reef, Western Australia: 1 minute 8 seconds, 11:58 a.m. AWST
- West Island, Ashmore Reef: 12 seconds at 12:04 a.m. AWST
- Com, Timor Leste: 64 seconds at 13:21 TLT
- Beaco, Timor Leste: 74 seconds at 13:19 TLT
- Cenderawasih Bay, West Papua, Indonesia: 1 minute 6 seconds at 13:52 WIT
What happens during a total solar eclipse?
Only in these very specific locations—touched by the path of totality—will it be possible to see a view of the Sun’s corona, its hotter, outer atmosphere, which is revealed for only a few precious minutes of totality. It looks majestic as it shines in a twilight sky as temperatures drop.
However, this is a super-short eclipse. The longest totality—during which the Sun’s spectacular corona will be visible as the sky turns to twilight—will be 76 seconds in Timor Leste.
That very short duration means that means eclipse-chasers will see an extended display of Baily’s beads—sunlight streaming through the mountains on the Moon—and get a better-than-usual view of the Sun’s pink chromosphere during totality.
What is a ‘hybrid’ solar eclipse?
This hybrid solar eclipse changes from annular (a “ring of fire,” where the Moon appears smaller than the Sun, so doesn’t block all of its light) to a total (where the Moon appears slightly larger, so blocks out all of the Sun’s light), then back to annular. How can that be—and what difference does it make to observers? “The term ‘hybrid’ describes the entire central path of the eclipse from start to finish,” said Fred Espenak, retired NASA astrophysicist, author, photographer and eclipse expert. “It refers to any eclipse that changes from annular to total or total to annular at some point along its path—due primarily to the curvature of the Earth bringing that part of the path closer to the Sun.” However, nobody actually sees a hybrid eclipse because it’s not a visual event in itself. “It’s just a description of the eclipse path as it changes from total to annular or annular to total—what you see is either a total, an annular or a kind of broken annular,” he said.
What is a ‘broken annular’ solar eclipse?
Halfway between a “ring of fire” and a total solar eclipse, there will be places—all very remote—where it will be possible to see (from a very precisely-positioned ship) beads of light around the Moon. The cause is the mountains and topography of the Moon—and it’s called a “broken annular” eclipse.
“If you do the classical computation then it’s very briefly an annular at the beginning and very briefly annular at the end,” said Michael Zeiler, a New Mexico-based eclipse cartographer who edits GreatAmericanEclipse.com and the co-author of the Field Guide to the 2023 and 2024 eclipses. “But if you correct for the lunar limb there is no true annularity at the beginning of the eclipse, it will be what I call a ‘broken annular’ and never a closed ring.” At the end of the eclipse, it’ll only be briefly be a true annular. “The duration will be less than one second.”
Where is the partial solar eclipse?
Here’s what a few key cities in the region will see of the partial solar eclipse at the “peak” of the event:
- Perth: 71% at 11:20 AWST
- Darwin: 81% at 13:22 ACST
- Dili, Timor Leste: 98% at 13:18 TLT
- Jakarta, Indonesia: 39% at 10:45 WIB
- Singapore: 16% at 11:55 ST
However, a partial solar eclipse is very different to a total solar eclipse. Even Dili at 98%—and towns in Australia close to Exmouth, such as Onslow (99%) and Coral Bay (98%)—will all see a 0% total solar eclipse. There is no totality, except within the path of totality—the central moon shadow.
What happens during a partial solar eclipse?
Over the course of a couple of hours the New Moon—which will be completely invisible—approaches the Sun and takes a bite out of it. That bite gets larger, peaks, then the Moon retreats, eventually leaving the Sun’s disk whole again. It’s great to see that first bite, and also the moments just before the end of the eclipse, but the key moment doing a partial solar eclipse is at peak eclipse when the biggest amount of the Sun is covered by the Moon.
However, it’s critical to appreciate that a 99% solar eclipse is not only not enough—it’s a completely different, lesser thing to experience than a total eclipse of the Sun. In eclipse-chasing, fortune always favors the very precise.
This article was first published on Forbes.com
All images: credit: Michael Zeiler/GreatAmericanEclipse.com (used with permission)