Check out today's astronomy picture of the day, featuring a numerical relativity visualization made by some folks i… https://t.co/Y4dMYs4LYp
A particular point with respect to which positions are measured. For example, positions on the Earth are frequently measured relative to the point on the Equator which is due South of Greenwich, England. In GPS coordinates, that point is given as 0,0 (its latitude is 0, and its longitude is 0). Or we might say something like “10 miles southeast of town hall.” In that case, town hall would be the origin.