Gaia's Lissajous Type Orbit
The animation shows the Sun-Earth system and all Lagrangian points of this system. There are five Lagrangian points in a system where two massive bodies revolve around their joint gravitational center. All these points are located in the orbital plane of the two bodies as shown in the illustration. If a third body of negligible mass is placed in orbit at any of the Lagrangian points, it will stay in equilibrium there.
Gaia will be placed in orbit around the L2 Lagrange point. Click on the magnifying glass icon to see an example of one orbital pathway that Gaia might follow around the L2 point. This is a Lissajous-type orbit (i.e. a near-circular ellipse or "halo") centered on the L2 point and orbiting around it on an axis that is perpendicular to the Earth-Sun axis.