Starry Night uses the old Julian calendar for all dates before Oct. 15, 1582, and the Gregorian calendar for all dates more recent than this. The dates Oct. 5-Oct. 14, 1582 do not exist in Starry Night, to account for the ten days which were skipped when the new calendar was introduced.
Interesting. I was investigating the sun's progression through the constellations and came upon a big jump from 1582 to 1583. Now I know why. Thanks.