Given the radius of the moon, its distance from the Earth, and its period of revolution, it can be calculated that the moon moves across the Earth's sky by its own diameter in about 2.1 minutes. The moon is visible in several of the Prokudin-Gorskii plates. The example above is especially clear. The animation alternates between "warped" color reconstructions based on the green exposure and the red exposure. Between the two exposures, the moon moves by more than 1/6 of its diameter, so it would appear that each exposure took upward of 20 seconds; the whole photo would have taken over a minute. From the brightness of the sky and the fairly short shadows, we can assume that this photo was taken during broad daylight. On an overcast day, the exposure would need to have been longer; indoors, much longer.