Total Eclipse: Countdown to History

Al Roker and Savannah Sellers look at the excitement building for the total solar eclipse, Neil deGrasse Tyson explains the science behind the phenomena with a surprise guest, and a behind-the-scenes peek at how eclipse glasses are made. » Subscribe to NBC News: NBC News Digital is a collection of innovative and powerful news brands that deliver compelling, diverse and engaging news stories. NBC News Digital features , , , Nightly News, Meet the Press, Dateline, and the existing apps and digital extensions of these respective properties. We deliver the best in breaking news, live video coverage, original journalism and segments from your favorite NBC News Shows. Connect with NBC News Online! Breaking News Alerts: Visit : Find NBC News on Facebook: Follow