In this gif you can clearly see the Moon's shadow moving from the West Coast of the U.S. towards the East Coast during the August 21 2017 eclipse.
DSCOVR (the satellite that imaged this) is located at the L1 point, which is exactly between the Earth and the Sun, meaning it always sees the sun-lit part of Earth.
But for a Solar eclipse to happen, the Moon also has to be exactly between the Earth and the Sun, and thus it should be visible in this gif.
At first I thought it was because DSCOVR was closer to Earth than the Moon was, but it's actually more than 3 times farther away.
Geometry dictates the Moon should be between the Earth and DSCOVR since DSCOVR itself is between the Earth and the Sun, so why isn't the Moon visible?