What do astronomers term the stretching of space that causes the distance between galaxies to increase?
contracting universe
maintaining universe
draining universe
expanding universe
An inflating balloon is not exactly like the expanding Universe. The surface of a balloon has only two dimensions, while space has three dimensions. But it is true that space itself is stretching out between galaxies like the rubber stretches when a balloon is inflated. This stretching of space, which causes the distance between galaxies to increase, is what astronomers mean by the expansion of the Universe.