Please be patient while the applet loads into your browser. Once it loads, this applet will display a system of binary stars orbiting one another, this time viewed along the plane of the orbit. Select a system from the menu labelled "Binary Systems", and the simulation will begin. You'll see a white window with one red dot and one blue dot. Clicking within this window will display the coordinates in Astronomical Units (AU). In the window labelled "Position and Time Data", the elapsed time (in years), positions (r_A and r_B in AU), and wavelength shift (dl_A and dl_B, in nm) for the two stars are constantly updating. In this applet, you will also see two "high-resolution" spectra: each spectrum appears to move due to the motion of the stars along your line of sight. Its shift with respect to the vertical line is the quantity "dl" displayed above. Please click on the icon (looks like an x or a /) in the upper right corner of the "stars" window before selecting a second system -- only one should be running at a time.