This dataset animates a sequence of images taken by the Earth Polychromatic Imaging Camera (EPIC) aboard the DSCOVR satellite, a partnership between NOAA and NASA. DSCOVR stands for Deep Space Climate Observatory and orbits the Earth 930000 miles away. It is at a special balance point called L1 where it always stays near a line connecting Earth and Sun. The images taken by EPIC always show a nearly fully lit Earth, rotating below with the land masses and cloud systems coming into view. The animation shown is a special case where the moon is passing in front of the Earth. If you look at SOS from a point where the Earth is fully lit, then the moon will appear properly round. This so-called lunar transit happens several times a year as seen from DSCOVR.
Note that the moon is fully lit as well in these images, though compared with the more reflective clouds on the Earth the appearance is a darker gray, instead of the brilliant white we see when looking at the full moon from Earth at night. The reflectance of the moon is roughly the same as the dry land masses on Earth and darker compared with the white clouds. Note that the contrast of these images is slightly higher than one would actually see if magically aboard the DSCOVR satellite.