🔭 Space Telescope — L2 Lagrange Point
Explore the Sun-Earth L2 Lagrange point where space telescopes like JWST reside. Adjust the halo orbit size, observe temperature equilibrium panels, and compare famous telescope configurations.
Telescope Presets
Orbit & Telescope
Thermal & Performance
~1.5 M km beyond Earth,
always in Earth's shadow.
Halo orbit ≈ 6-month period.
Teq = T☉·(R☉/2d)^(1/2)
Shield: Tcold ~ 40 K
Why L2?
The Sun-Earth L2 point is located ~1.5 million km beyond Earth away from the Sun. It is a quasi-stable equilibrium where the gravitational attraction of the Sun and Earth cancel with the centrifugal force of the co-rotating frame, allowing objects to orbit there with minimal station-keeping. The key advantage for infrared telescopes: a sunshield can simultaneously block light from the Sun, Earth, and Moon, allowing the telescope's mirror to cool to extremely low temperatures (~40 K for JWST's cold side). JWST observes in infrared wavelengths requiring temperatures below 50 K — impossible in Earth orbit where the telescope would be alternately heated and cooled as it enters/exits Earth's shadow. At L2, a single 5-layer sunshield provides a stable, cold thermal environment, enabling observations of the earliest galaxies and exoplanet atmospheres.