Ask Dr. Universe

Dear Dr. Universe: I was wondering, how does an eclipse happen? – Susan, 13, San Francisco, CA

Dear Susan,

It just so happens the Great American Eclipse is coming up on August 21, 2017. This solar eclipse will be the only one visible from across the lower 48 states in nearly a hundred years. When it happens, parts of the country will experience darkness for a couple minutes during the day.

It seems prime time to answer your question. My friend Guy Worthey, an astronomer at Washington State University, was happy to help out.

“Do you have a little brother or sister? And maybe a TV?” Worthey aske...