Shifting your position in space isn't the only way to watch the constellations bend. You can also shift your place in time.

You're looking at the constellation Lyra back in 4713 B.C. Press the P button in the Time and Date display to move forward in time and see how it changes. You can see that the bright star Vega is moving in relation to the other stars in Lyra. The other stars are moving, too, but Vega appears to move faster because it's much closer to Earth.

Each star in the sky is in motion in at least two ways. All the stars we can see by eye are our travelling companions in a long rotational journey around the center of our galaxy. They generally move together as a group, but like a single fish swimming in a school that's riding an underwater current, each individual star has a separate motion relative to the others.

This motion—called proper motion—is the actual movement of the stars in different directions and at different speeds though space.

Click here to turn on the proper motion vectors for the stars. These vectors show the motion and direction the stars are moving relative to each other. It takes a long time to measure these vectors, because the motion is very gradual on a cosmic time scale, and the changes appear so small when even the closest stars are so far away from us.

Our familiar constellations look much the same now as they did at the end of the last ice age, but in the distant future they will become distorted because of the proper motion of the stars. Eventually, people on Earth will have to invent new constellations!