Why is the Earth-Sun L2 point useful for space observatories such as the James Webb Space Telescope?

The Earth-Sun L2 point is a highly advantageous location for space observatories like the James Webb Space Telescope (JWST) due to its unique position in celestial mechanics. Located approximately 1.5 million kilometers from Earth on the side opposite the Sun, L2 allows a spacecraft to remain in a relatively fixed position relative to the Earth-Sun system.12

This location is particularly useful for infrared observatories because it provides a stable environment to shield sensitive instruments from thermal radiation. By positioning the telescope at L2, the spacecraft can utilize a large sun shield to simultaneously block heat and light originating from the Sun, Earth, and the Moon. This protection is essential for the JWST, as it must maintain extremely low temperatures to effectively detect faint infrared signals from distant galaxies and protostars. While L2 is an unstable Lagrange point, spacecraft can maintain their position by performing station-keeping maneuvers, such as orbiting the point in a Lissajous pattern.12