This is an actual Astrolabe: part of the collection held at the National Maritime Museum in Greenwich. Astrolabes were ancient astronomical devices, popular in the Islamic world a thousand years ago, and then in medieval Europe.
They enabled people for the very first time to find their exact positions, wherever they were, even at sea, and navigate from there. They were analogue computers – like the GPS of their day!
It was when I started to think about Astrolabes that I made a breakthrough with the starships in my book. What if there was a science-fiction version of the Astrolabe: an incredibly powerful navigational device that enables people to cross the great gulfs of interstellar space? What if you could actually go into one of these devices: if it allowed your consciousness to move through space, faster than the speed of light – even at the Speed of Dark?!