That observation was the first hint that, not only is the Earth not the centre of things, but those things are vastly, almost incomprehensibly, bigger than people up until that date had dreamed. And they have been getting bigger, and also older, ever since. Astronomers’ latest estimates put the age of the universe at about 13.7 billion years. That is three times as long as the Earth has existed and about 100,000 times the lifespan of modern humanity as a species. The true size of the universe is still unknown. Its age, and the finite speed of light, means no astronomer can look beyond a distance of 13.7 billion light-years. But it is probably bigger than that.
Nor does reality necessarily end with this universe. Physics, astronomy’s dutiful daughter, suggests that the object that people call the universe, vast though it is, may be just one of an indefinite number of similar structures, governed by slightly different rules from each other, that inhabit what is referred to, for want of a better term, as the multiverse.
Galileo, four centuries on: As important as Darwin (The Economist):