The James Webb Space Telescope orbits the Sun near Sun-Earth Lagrange point 2 (L2), approximately 1.5 million kilometers (1 million miles) from Earth. L2 is one of five Sun-Earth Lagrange points, positions in space where the gravitational pull of the Sun and Earth balance the orbital motion of small objects (like spacecraft or asteroids). At these points in space, the gravity of the two large objects balances the orbital motion of the third object. Lagrange points can be used by spacecraft to reduce propellant consumption needed to remain in position. Objects in that region have the same orbital period (length of year) as Earth. As the Earth moves around the Sun the L2 point moves as well, so the Sun, Earth, and L2 always form a straight line. This makes it possible for Webb to remain in constant communication with Earth, since it is always in the same direction and at roughly the same distance from our planet. Webb is not located exactly at L2, but instead orbits L2, completing one circuit every 168 days. This "halo orbit" around L2 is highly elliptical and is roughly perpendicular to its orbital path around the Sun. The distance between Webb and L2 varies between about 250,000 and 830,000 kilometers (150,000 to 500,000 miles). Because of this complex orbit, Webb's precise distance from Earth varies over time. Sizes and distances in this illustration are not to scale. Credit: NASA, STScI.
