Imagine you are an ordinary interstellar starship commander. You set off on a trip to a nearby star, accelerating to a significant percentage of the speed of light. You know that after a certain period of time you must slow down. But before you start the maneuver, you check your speed and position. A quick look out of the window should confirm everything.
That’s when the problems begin. The pattern of stars outside is nothing like the one where you started so you can no longer use the familiar constellations to help you orient and navigate. It turns out that navigating is much harder for starship commanders than you imagined.
In the future, however, you and your colleagues will be able to turn to the work of Coryn Bailer-Jones at the Max Planck Institute for Astronomy in Germany who has developed a way to determine the position and velocity of a spacecraft traveling through our neighborhood. His approach can pinpoint position to within about 500 million kilometers, just a few times the distance from the Earth to the Sun.