Earth is,
spinning (at the Equator) ~ 1,037 mph
orbiting the Sun ~ 67,000 mph, or ~ 18.6 miles/sec
Solar System orbiting the center of our Milky Way galaxy ~ 448,000 mph, or ~ 125 miles/sec
1,037 mph (at the Equator)
67,000 mph, or ~ 18.6 miles/sec
448,000 mph, or ~ 125 miles/sec
What is unknowable is the speed of the universe. How can we assume it is motionless?