The James Webb Space Telescope
An infrared space observatory
The largest telescope ever sent into space, built by NASA with the European and Canadian space agencies. It sees in infrared, which passes through the dust that hides newborn stars and which is all that reaches us from the first galaxies, whose light has been stretched to those wavelengths on its way across the expanding universe.
Its 6.5-metre mirror of 18 gold-coated segments sits behind a sunshield the size of a tennis court that keeps it below -223 °C. It does not orbit Earth: since January 2022 it has circled the L2 point, 1.5 million km away on the side facing away from the Sun, where the Sun, Earth and Moon all stay behind that shield.
Key figures
- Launched
- December 25, 2021, on an Ariane 5 from Kourou
- Arrived at L2
- January 24, 2022
- Primary mirror
- 6.5 m, 18 gold-coated segments
- Sunshield
- 21.2 × 14.2 m, 5 layers
- Instruments kept at
- below -223 °C
- Observes in
- Red and infrared, 0.6 to 28.5 µm
- One loop around L2
- about 6 months
- Built by
- NASA, ESA and CSA