Dynamical Perturbation of Stars

In this simulation, you see a hypothetical star system with one planet orbiting the star. We begin with a planet of very small mass at a large distance away. If you watch the spectrum of the star, you should see very little noticeable change in the position of the spectral lines as the planet orbits.

Now change the mass of the planet or its distance from the star. As you do so, you should begin to notice slight, but increasing shift in the positions of the star's spectral lines. The lines will shift back and forth as the star is pulled by the planet. The larger the shift, the larger (or closer) the planet.