What's Your Sign? The Precession of the Equinoxes

Notice that the date in the status bar is set to 600 B.C. The intersection of the ecliptic and celestial equator is in western Aries.

Press the S button in the Time and Date display a few times to move through time in intervals of 50 years. Notice how the intersection slowly moves west. The ecliptic does not move, but the celestial equator does.

The vernal equinox crossed from Aries into Pisces around the time of the birth of Jesus (and that of the astronomer Hipparchus), according to modern constellation boundaries.

Move the time forward until you reach the year 2000. Notice that the intersection (which is still called the "first point of Aries") has slipped most of the way through Pisces.

In six more centuries, it will leave Pisces altogether!