Why do total solar eclipses happen? Learn what will cause tomorrow's celestial show.

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.