I add, from Blessed Pope John Paul II (2003):
"Just as *Lauds *is prayed at daybreak, so *Vespers *is prayed close to sunset, at the hour when, in the temple of Jerusalem, the burnt offering was made with incense. At that hour, after his death on the Cross, Jesus was lying in the tomb, having offered himself to the Father for the salvation of the world.
The various Churches, following their respective traditions, organized the Divine Office in accordance with their own rites."
vatican.va/holy_father/jo…031015_en.html
So we see that the ordinary may assign a time in the evening which may be near sunset, and we know that in various latitudes the sunset is at different times, for example:
Stockholm, Sweden 59.3 N, 2:48 pm
London, England 51.5 N, 3:54 pm