How did DSCOVR capture the Moon's shadow on Earth during the August 21 2017 solar eclipse without the Moon itself also being visible?
DSCOVR is in a large Lissajous orbit around the Sun-Earth L1 point, about 1,500,000 kilometers from the Earth. At this point it is far from the line drawn between the Sun and Earth; if the Sun were behind you and you were looking at the Earth-Moon-DSCOVR system, you would say that the spacecraft is down and to the right by several hundred thousand kilometers.
I've used the Python package Skyfield plus a location for DSCOVR from JPL's Horizons to plot their positions. Earth is large and blue, the Moon is green (cheese) and smaller, and the very tiny black spot is DSCOVR. In each case I've annotated DSCOVR's position.
I've done some rotations so that my X-axis passes through the centers of the Sun and the Earth during the eclipse.
If I get a chance I'll make a 3D plot of DSCOVR's orbit. The script I used can be found in https://pastebin.com/AXsJM8J1