KINGSTON, R.I. – April 5, 2024 – Millions of people across the country are expected to flock to a narrow swath of the U.S. on Monday, April 8, as a total eclipse of the sun darkens skies over the U.S. for the first time in almost a decade.

The solar eclipse will extend a ribbon of total darkness – about 120 miles wide – diagonally across the U.S. – from Texas to Maine, passing to the west of Rhode Island as it cuts across northwestern New York. People in the lower 48 states will see at least a partial eclipse. In Rhode Island, we will see about 90% totality as the moon passes in front of the sun, leaving a sliver of the sun visible. 

To get in on the celebration, the University of Rhode Island’s Department of Physics is hosting an eclipse viewing party on Monday. There will be food and drinks provided by URI’s Community Policing Unit, commemorative T-shirts, free eclipse glasses (while supplies last), and multiple telescopes and pinhole projector setups to get a great view of the eclipse. It is important to take proper precautions to protect your eyes from damage in viewing an eclipse. The event is from 2 to 4 p.m. on the Quad outside East Hall. Peak totality for us is expected at about 3:28 p.m.

“We’ll have faculty, staff, and students present from 2 to 4 p.m. to answer questions and help people safely observe the eclipse,” said Rob Coyne, an associate teaching professor in physics. “There will be multiple telescopes, pinhole projectors and eclipse glasses to enable people to get close-up views of the sun.”

(Health Services will also have a table on the Quad from noon to 3 p.m. providing information about how to safely view the eclipse, and Student Engagement will be offering eclipse viewing classes.)

Coyne, whose research interests include gravitational wave astrophysics and gamma-ray astronomy, agreed to answer some questions about solar eclipses – providing a light in the darkness.

What is a solar eclipse and what governs its occurrence? What’s special about a total solar eclipse?

A solar eclipse occurs when the moon passes between the sun and the Earth, blocking the light of the sun from reaching us. So, the thing that we’re seeing during a solar eclipse is really just the moon casting its shadow on the Earth’s surface. In that way, it’s not entirely unlike holding up your own hand to shield your eyes from the sun (your hand’s shadow shades your eyes from the bright light), except the moon is a whole lot bigger than your hand, so the shadow is a whole lot bigger, too.

For this to occur, a couple of things need to happen. First, the moon needs to be on the correct side of Earth. Since the moon orbits Earth (a little faster than once per month), it spends roughly half of its time behind Earth (farther from the sun) and half of its time in front of Earth (closer to the sun). Despite this, solar eclipses are still relatively rare because the moon also needs to line up with the sun just right so that its shadow falls on Earth.

Even then, solar eclipses happen more often than you might realize. On average there are a few—no more than five—solar eclipses per year! But there are two things that make total solar eclipses extra special. 

First, during many eclipses the moon and sun aren’t lined up perfectly—so the moon only covers a portion of the sun. These “partial eclipses” are still exciting, but they’re not quite as visually striking as a total eclipse. And even if the sun and moon are perfectly lined up, the moon isn’t always exactly the same distance away from Earth. When the moon is farther away, it looks smaller, and it won’t appear large enough in the sky to completely block out the sun. This result is known as an “annular eclipse” where a very thin ring-like portion of the sun is still visible behind the moon.

Second, the shadow that the moon casts is relatively small compared to Earth’s surface. It’s usually less than 150 miles wide—sometimes much less. So, it’s very rare that the shadow will pass over the same place twice, which means that having a total solar eclipse that is visible in a place near you is quite special. In fact, the next total eclipse visible from the United States won’t be until 2033, and it will only be visible from Alaska. The next total eclipse to touch the lower 48 states won’t be until 2044, and the next significant total eclipse that will pass over more than one or two states won’t be until 2045. 

Rhode Island is outside of the totality zone. So, what should we expect here?

Here in Rhode Island, we’re going to observe a partial solar eclipse where about 90% of the sun will be obscured. This means we’ll still get to see a very visually impressive eclipse—only the tiniest sliver of sunlight will be able to sneak past the moon. The effect won’t be quite as dramatic as it would be if we were in the path of totality, where day will turn to night for a few minutes. But we can still expect significant darkening of the sky, and a beautiful display of celestial motion as we watch the moon dance across the surface of the sun.

What precautions should people take to view the eclipse? Can it really damage your eyes? Is there a place on campus where students can get a pair of viewing glasses?

Looking directly at a solar eclipse with the naked eye is very dangerous. While much of the sun will be obscured by the moon, the part that remains visible is still just as bright and can cause significant damage to your eyes. Even when the sun is completely blocked, the moment it comes out again can be quite dangerous. Under no circumstances should anyone look directly at the solar eclipse without certified protective eyewear.

It’s important to note that ordinary sunglasses are NOT safe for solar viewing.

The good news is that there is still time to get viewing glasses. The American Astronomical Society has put together a list of suppliers who are known to provide safe and certified solar viewing equipment. They are available on many well-known online platforms and in some local stores.

But even if you can’t get your hands on certified eye protection, there are a lot of great indirect ways to view the solar eclipse, such as pinhole projectors, that people can safely make at home with household materials.

Does a solar eclipse – or lunar eclipse – present scientists with an opportunity?

Yes! Solar eclipses have a long history of enabling scientific discovery. One of my favorite examples—that is near and dear to my heart—is when Sir Arthur Eddington and Sir Frank Dyson used a 1919 solar eclipse to prove the light-bending predictions of Einstein’s (then recent) theory of general relativity. And this trend to use eclipses as opportunities for study continues through today.

For example, during this upcoming eclipse, NASA plans to perform several studies, including using the eclipse to allow direct observations of the sun’s atmosphere (called the corona), measuring how the sudden decrease in sunlight affects our atmosphere, and more. Plus, many of us scientists are also avid science enthusiasts. So, we’re excited for the opportunity to see the eclipse ourselves, too.