NASA @NASA
During an eclipse, 2 shadows are cast: the umbra & the penumbra. The umbra is where the Sun is completely hidden behind Earth. The real action begins when the Moon starts to disappear as it enters the umbra at about 6:48am ET/3:48am PT. Watch live online: https://t.co/r6X6Sp3R9X https://t.co/V5V — PolitiTweet.org