October 11, 2023
If skies stay clear this weekend, a solar eclipse may be visible over Philadelphia.
An annular solar eclipse will take place on Saturday, Oct. 14. Annular solar eclipses occur when the moon passes between the sun and Earth while it is at its farthest point from Earth. As the moon does not fully cover the sun, the sun's rays peek around, causing a "ring of fire" effect.
Weather permitting, Philadelphians will be able to see the eclipse between 12:05 p.m. and 2:37 p.m., with the moon's maximum coverage of the sun occurring at 1:21 p.m.
"If you use the proper eye protection, which you absolutely must have to look directly at the sun during an eclipse, you'll see the moon slide across the lower edge of the disk of the sun," said Derrick Pitts, the Franklin Institute's chief astronomer.
While multiple eclipses can occur over the course of a year, they can happen anywhere on the planet based on a complicated pattern that shifts every few decades, according to Pitts. So, Philadelphians can consider themselves lucky this time around to be somewhat near the eclipse's path — which will cross North, Central and South America.
"The annular eclipse path goes from Oregon, down across the southwestern United States and off the coast of Texas, into the Gulf of Mexico, then through Central America and into South America," Pitts said. "So if you're along that path, you'll get to see the ring eclipse, and the path is something like 120 miles wide. If you're not in that path, then it looks like a partial eclipse. And the farther you move away from the center line, less of the sun will be covered by the moon. So for us here in Philadelphia, only 25% of the sun's disk will be covered by the moon."
With 75% of the sun still shining through in Philadelphia, typical eclipse effects — such as darkness and temperature changes — will be avoided.
"You won't even really know what's happening because ... there's not much reduction in brightness of the sun, virtually none," Pitts said. "If you didn't know there was an eclipse happening, you wouldn't know there was an eclipse had."
This eclipse will be different than the upcoming total solar eclipse on April 8, 2024, which will completely block the face of the sun. April's eclipse, which will cut through Pennsylvania as it crosses North America, will likely darken local skies, according to Pitts.
For those hoping to catch a glimpse of the eclipse, there are several direct and indirect methods of doing so, according to Pitts.
People who plan to look directly at the eclipse must use protection to keep their eyes safe.
"Certified-safe solar eclipse glasses will work fine," Pitts said. "You can't use sunglasses, you can't use smoke filter glass, you can't use the silver lining from the Pop Tarts envelope. You can't use any kind of goofy stuff like that."
Solar eclipse glasses are available at the Franklin Institute's Sci-Store, located on the second floor of the museum. Welding glasses with number 14 shades are an acceptable choice for eye coverings as well, according to Pitts.
One indirect viewing method uses a "pinhole projector," which can be made by poking a hole in a piece of aluminum foil. The viewer can stand with their back to the sun and hold the foil so the sunlight falls onto it. A dot of light should stream though the hole, and it can be focused onto an adjacent wall so an image of the sun comes into focus.
"You can watch the progress of the moon across the disk of the sun indirectly with your back to the sun," Pitts said.
Other items with small holes, like colanders or pegboards, can be used for a similar effect.
At the Franklin Institute, Pitts is hosting a Solar Eclipse Gathering from 11 a.m. to 3 p.m. During the event, Pitts will guide visitors through livestreams of the eclipse, and a DJ will be on hand.
Of course, the possibility of seeing the eclipse at all will depend on whether the sky is clear enough. If the sun is hidden behind clouds, then the eclipse won't be visible, Pitts said.
While the forecast for Saturday calls for rain in Philadelphia, stargazers needn't fret: NASA will stream live feeds of the eclipse.
Regardless of the weekend's weather, Pitts says Philadelphians should go about their normal weekend routines — but bring along their solar eclipse glasses in case of clear skies.
"What I'm suggesting to people is that they shouldn't disrupt their day's activities," Pitts said. "They should make sure they get some solar eclipse glasses. Then, while they're out and about doing stuff between 12:00 and 2:30, they should put the glasses on, glance up at the sun to see what's happening and then continue about their daily activities."
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