The next total solar eclipse takes shape Monday, April 8, when an overlap between the sun and the moon is expected to darken daylight skies over parts of North America and ask awestruck Earthlings to briefly reckon with their place in the universe. It will mark the United States’ first total solar eclipse since August 2017, although experts say this upcoming astral event could prove to be even more impressive than the last.
Here’s what to know about total solar eclipses and why they occur.
What exactly is a solar eclipse?
Eclipses of all types are caused by an alignment in space between the sun, moon and Earth. Their precise choreography results in one celestial body obscuring another, and, depending on whether the moon is positioned on the side of Earth nearest the sun or farthest from it, the moon either casts its shadow onto Earth or vice versa. During a lunar eclipse, like the one that appeared over much of the Western hemisphere in late March, all three align with Earth sandwiched in between. That sometimes allows people to watch as a shadow of the planet, backlit by the sun’s rays, moves across the moon’s surface.
Their alignment is switched during a solar eclipse. The moon, while orbiting Earth, passes between the planet and the sun in such a way that it appears to cross directly in front of the star, temporarily blocking its light from view. With the sun behind it, a shadow of the moon is cast onto Earth.
