why do planets move around stars in the same level ?
why do stars move around black holes in the same level?
why don't some of them move in horozintal level & the others in vertical level?
Consider a train , its proper length = 375000 km , traveling at a speed of 180000 km/sec (0.6 of speed of light) relative to person (name him B)
Consider a beam of light that travels in the same direction of the train
The train traveler (name him A) will measure the train length = 375000...