Tens of millions of people came out to view the 2017 total solar eclipse, the first in the US in nearly four decades. Now we are approaching an even more exciting, back-to-back pair of US eclipses: an annular eclipse on Oct. 14, 2023 and a total solar eclipse on April 8, 2024. You won't want to miss them, and there's no better way to prepare than to use the free app "Totality by Big Kid Science" (expected to be downloaded and used by millions) and...