What is a solar eclipse?

Solar eclipses occur when the sun, moon and Earth align. The moon passes between Earth and sun, temporarily blocking the sun’s light and casting a shadow on Earth.

A total solar eclipse is when the moon fully obscures the sun, whereas a partial solar eclipse means it blocks just a portion of the sun’s face.

olar eclipses occur only with the new moon. Because the moon’s orbit around Earth is tilted, the three bodies don’t always line up in a way that creates an eclipse.

“Imagine if the moon’s orbit were in the plane of Earth’s orbit around the sun — if that were the case, then every new moon, you’d have a total solar eclipse and every full moon, you’d have a lunar eclipse,” Neil DeGrasse Tyson, director of the Hayden Planetarium at the American Museum of Natural History, told NBC News. “So, because things don’t always align, it lends to the rarity of the event and the specialness of the event.”

Where and when will the eclipse be visible?

This year’s eclipse will follow a slightly wider path over more populated areas of the continental U.S. than other total solar eclipses have in the recent past.

NASA estimates that 31.6 million people live within what’s known as the path of totality, where the total solar eclipse will be visible. An additional 150 million people live within 200 miles of the path, according to the agency.

Path of the solar eclipse

On April 8, the moon will block out the sun in parts of the Midwest and Northeast.

The path travels through Texas, Oklahoma, Arkansas, Missouri, Illinois, Kentucky, Indiana, Ohio, Pennsylvania, New York, Vermont, New Hampshire and Maine. Tiny parts of Michigan and Tennessee will also be able to witness totality if conditions are clear.

After the eclipse crosses into Canada, it will pass over southern Ontario, Quebec, New Brunswick, Prince Edward Island and Cape Breton, at the eastern end of Nova Scotia.

Those outside the path of totality can still take part in the astronomical event by viewing a partial solar eclipse — visible throughout all 48 states of the contiguous U.S. — or a NASA livestream.

The timing, including how long totality lasts, depends on the location, but some spots will see the moon fully cover the sun for up to 4 minutes and 28 seconds.

When is the next solar eclipse?

The next total solar eclipse will be in 2026, but it will mostly pass over the Arctic Ocean, with some visibility in Greenland, Iceland, Portugal and northern Spain. In 2027, a total solar eclipse will be visible in Spain and a swath of northern Africa.

The next total solar eclipse visible from North America will be in 2033, but only over Alaska. Then in 2044, a total solar eclipse will cross Montana, North Dakota, South Dakota, parts of Canada and Greenland.

The next total solar eclipse to cross the continental U.S. coast-to-coast in will occur in 2045. The path of totality for that eclipse will cut through California, Nevada, Utah, Colorado, New Mexico, Oklahoma, Kansas, Texas, Arkansas, Missouri, Mississippi, Louisiana, Alabama, Georgia and Florida.