Celestial Navigation

screen capture from Celestia with labels off
Can you find Earth 150 million kilometers away? Move your mouse over the image to see it labeled.

Have you ever wondered how those folks on the Enterprise found their way around? Imagine it. You’re in space, a mere light year from Earth (10 trillion kilometers or 6 trillion miles.) Could you find your way home? It sounds easier than it is.

Most of us have trouble looking up at the night sky and identifying more than a handful of stars and planets. And those are ones we see all the time, for the most part right where we expect them to be, at least as far as their position relative to the horizon and other celestial objects goes.

Now, take away that frame of reference. What if there are no constellations with neat names like Orion and The Big Dipper. Now what do you do?

The Star Trek folks likely have a massive database at their disposal, a catalog of countless stellar bodies, listing the unique radiation signatures of each, along with a three-dimensional reference. The ship’s sensors pick out a few known objects at measurable angles from one another, and then the computer calculates where you are in relation to them. Simple.

And if you don’t have that stellar map? Well, you could just turn on planetary labels.


Celestia is an open source space simulation. It lets you see what it’s like to explore space not just as an earth-bound observer, but from virtually any vantage point in the cosmos. Take a look at the screen captures of Celestia shown here.

The first shows what the Earth looks like from the Sun, a distance of 1 AU, or 150 million kilometers, or 93 million miles. That’s about 8 light minutes; nothing compared to the light year we mentioned earlier. Still, Earth is a bit hard to pick out, isn’t it.

Move your mouse over the image to see the same configuration with planetary labels turned on. (You may need JavaScript enabled in your browser.) Now it’s much easier to find our way home.

Want to see more? Download Celestia for yourself and try it out.

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Jonathan Mycroft is a freelance writer and author. His latest novel, Trial by Fear, is now available as a pocket book and as a downloadable e-book from Lulu.com. Visit his website at www.jonathanmycroft.com