Some cool images have been bouncing around IO9 for the past few days, related to the orbits of our Solar System, and attempting to point out some fallacies.
The first is a video that attempts to illustrate the fact that, although it seems the planets orbit the Sun in a more or less circular, or heliocentric, orbit… in fact, the Sun is orbiting the Milky Way galaxy at 43,000 miles per hour… and the Milky Way itself is moving at 1.3 million miles per hour. The result: The planets are all moving in a helical orbit, being pulled along by the Sun’s gravity.
The first video (above) is a nice way to envision this. It’s also wrong, of course.
As Robert T. Gonzalez points out on IO9, the video’s text is embarrassingly incorrect on some points; for instance, nothing about the helical orbit is the same as a vortex. Also, the imagery (besides not showing the Sun, the planets and their orbits to scale) depicts a Solar System moving like a disc oriented at ninety degrees to its direction of movement. In fact, it’s more like a 60 degree angle, which means (if you think about it) that each planet alters its velocity through space during orbit, traveling faster as it moves from the trailing edge of its orbit to the leading edge, and moving slower as it moves from its leading to trailing edge.
(Actually, I wonder if the constant change in velocity means that the orbits are not actually helical, but something else… but I’m not familiar enough with celestial mechanics, nor the definitions of complex motions, to say.)
Robert found a second graphic that depicts the angle of the orbits and their movement through space, which he maintains is a better one than the YouTube video:
Either way, this gives you a little perspective on how we’re really traveling through space, and it’s even cooler than Galileo could have imagined.