During the summer solstice, nighttime does not get beyond astronomical twilight, a condition which lasts throughout the month of June.
It is possible to view both astronomical dawn and dusk every day of the month of May.
[3] Starting at the Prime Meridian and heading eastwards, the parallel 50° north passes through: From the signing of the 1875 Treaty of Saint Petersburg until the Russo-Japanese War which broke in 1904, the Russian Empire had full control of Sakhalin island.
As a result of the 1905 Treaty of Portsmouth that brought an end to the Russo-Japanese War, the portion of the island south of the 50th parallel line became Japanese territory, part of Karafuto Prefecture.
However, following the month long Soviet–Japanese War during the summer of 1945, the entire island was reunified under Soviet control.