The Universe is everything that we can ever know – all of space and time.
The Universe is almost entirely empty, with small clusters of matter and energy.
The Universe is probably about 15 billion years old, but estimates vary.
One problem with working out the age of the Universe is that there are stars in our galaxy which are thought to be 14 to 18 billion years old – older than the estimated age of the Universe. So either the stars must be younger, or the Universe older.
The furthest galaxies yet detected are about 13 billion light-years away (130 billion trillion km).
The Universe is getting bigger by the second. We know this because all the galaxies are zooming away from us. The further away they are, the faster they are moving.
The furthest galaxies are spreading away at more than 90 percent of the speed of light.
The Universe was once thought to be everything that could ever exist, but recent theories about inflation suggest our Universe may be just one of countless bubbles of space-time.
The Universe may have neither a center nor an edge, because according to Einstein’s theory of relativity, gravity bends all of space-time around into an endless curve.