Day and night occurs because the Earth is spinning on
its axis.
As the Earth orbits the Sun it spins on its axis once every 24 hours. We call
this time one day.
In one day every point on the Earth's surface will come out of
night, go through a day, dusk and then into night once more.
If you were standing on the equator you would be
travelling round at roughly 1600 km/hour (1000 mph) due to this rotation. At latitude 51o N
you would be moving at just over 100 km/hr (630 mph) as you have a smaller distance to
travel in the same time.
Dusk is due to the sunlight filtering through the atmosphere
of the Earth. On a planet or moon with no atmosphere the transfer from day to night would be
instantaneous with no dusk.
The Sun (and planets, stars and the Moon) rise in the
east and set in the west. This means that countries further east of an observer will move into
daylight first and so sunrise will be earlier the further east you go.