About 31 million people in the United States will be able to witness a rare event this spring that won't happen again for another 20 years.
A total solar eclipse will occur briefly over a dozen states on April 8. It will be the last total solar eclipse visible from the US until 2044.
A total solar eclipse happens when the moon passes between the sun and earth, completely blocking the face of the sun.
People viewing the eclipse from locations where the moon's shadow completely covers the sun – known as the path of totality – will experience a total solar eclipse, according to NASA. The sky will darken, as if it were dawn or dusk, and people along the path of totality will see the sun's corona, or outer atmosphere, which is usually obscured by the sun's brightness.
The solar eclipse's path of totality will move through the country beginning in Texas around 12:23 p.m. CT and ending in Maine around 4:40 p.m. ET.
An estimated 31.6 million people live in the path of totality, according to NASA. It will be able to be seen in parts of Texas, Oklahoma, Arkansas, Missouri, Illinois, Kentucky, Indiana, Ohio, Pennsylvania, New York, Vermont, New Hampshire and Maine. Small parts of Tennessee and Michigan will also experience the total solar eclipse.
You don't need to live within the path of totality to see the eclipse. NASA says 99% of people who reside in the US will be able to see the partial or total eclipse from where they live. Every state, plus parts of Alaska and Hawaii, will experience at least a partial solar eclipse.
What you can see during a total solar eclipse depends on the weather and the location from which you view it. You need clear skies to have the full eclipse experience, with a clear view of the sun and moon. To see all stages of a total solar eclipse, you must view it from somewhere along the path of totality. Observers viewing the eclipse from outside the path of totality may observe a partial eclipse, where the moon covers most but not all of the sun.
Totality only lasts a minute or two, according to NASA. You may be able to see a 360 degree sunset, some particularly bright stars or even planets in the darkened sky. The air temperature will drop and often an eerie silence will settle around you.
A total solar eclipse is the only type of solar eclipse where skywatchers can momentarily remove their eclipse glasses and view the sun with the naked eye, according to NASA. Glasses can be safely removed during totality, since the moon is completely blocking the sun. Otherwise, it's not safe to look directly at the sun without specialized eye protection for solar viewing.
NASA recommends using solar viewing glasses ("eclipse glasses") or a handheld solar viewer, both of which are thousands of times darker than regular sunglasses. You can also use an indirect viewing method such as a pinhole projector, which has a small opening and projects an image of the sun onto a nearby surface.
If you aren't able to see the eclipse or want to check it out up close, NASA is hosting a live broadcast of the event with views across the path, expert commentary and more, beginning at 1 p.m. ET on April 8.
The last total eclipse was in 2017 and was experienced by around 20 million people.