Asked by Sophie Roberts
We don’t know. This is actually one of the ‘big questions’ currently in the field of space science. This particular mystery is one that has many questions surrounding it, possibly the most relevant being, “is the universe finite?” There is still no universally agreed answer. One camp believes that it must be but others disagree. It is possible to see a sphere around the Earth of around 50 billion light-years from middle to edge. This makes up the observable universe but is unlikely to be the full extent of space, this is just the visible part.
Even if we agree that the universe is finite and has an edge, what is at the edge is another topic up for debate. One of the strongest theories for the geometry of the universe is that it is like a giant expanding balloon. The effect of this geometry is that looking far enough in any particular direction will cause the same thing to be seen.
Ultimately this question probes the very nature of the universe and as of yet has no concrete answers, but that is exactly why it is fascinating.
Answered by Josh Barker from the National Space Centre
Image courtesy of NASA