Building a Planetary Road Sign
There must be many of them: those funny signposts that indicate the direction and the distance to places that are usually quite far away. Tokio 9597 kilometers, Kinshasa 6379 kilometers, Mahabalipuram 8106 kilometers.
Wouldn’t it be nice, I thought a few weeks ago, if there was a signpost like that showing the directions and distances for the sun, the moon and the planets? Why doesn’t such a planetary road sign actually exist?
Of course I immediately knew the answer. The planets all have their orbits around the sun and the moon revolves around one of those planets: the Earth. And the Earth also revolves around its own axis. Everything is constantly on the move.
The distance to Tokio is always the same. But the celestial bodies are never in the same place and the distances are anything but constant.
That does not mean that you can not build a planetary road sign, but by definition it will be a pretty complex object.
Fortunately everything moves more or less in the same plane, the ecliptic. But the angle of that plane with the earth’s surface varies in the course of a day, and in the course of a year. So the axis of the signpost must be able to move along with the ecliptic. In addition, the direction signs must all be able to rotate independently about that axis.
For those variable distances, digital displays are inevitable. The distance between Earth and Mars can be anything between 56 and 400 million kilometers. The difference can easily be half a million kilometers per day, or a few hundred kilometers per minute. As a result, the last digit changes several times per second.
Everything is possible in 3ds Max and Photoshop. A planetary signpost might look something like this:
When I posted this picture on Facebook, several people thought that it was real and that the planetary road sign could already be admired somewhere. I take that as a compliment; that’s what you aim for as an impression artist.
Unfortunately, for the time being, this signpost only exists digitally. I lack the technical knowledge, and the funds, to build a real one. The Facebook discussion however did generate some suggestions for potential sponsors: the European Space Agency, science museum Nemo or Delft University of Technology. And it would of course be a great interdisciplinary student project.
There were also ideas for a web-based version (VRML / WebGL) or a desktop model. And I got the recommendation to add an extra sign, pointing down: Terra 6378 kilometers.
So: to be continued, hopefully.