Flight Sheremetyevo International Airport departs from Moscow Sheremetyevo International Airport at 18:35 and arrives at Seoul Incheon International Airport at 09:40.
The flighttime is about 9h 05m. The distance travelled ("as the bird flies"): 9744 Km. So the average speed is roughly 1073 Km.
There is an 6 hour time difference between Moscow and Seoul