The vastness of outer space

When it comes to measuring the vastness of outer space, you need to talk about time in order to talk about distance. Watching the night sky with my children, I tell them that the starlight now reaching our eyes is ancient. Some of it originated when dinosaurs stood where we are now standing; some of it before life even existed on Earth. I’m using a little poetic licence when I say this. Technically, the oldest light our unaided eyes can see is no more than 2.5 million years old and comes fr...