The James Webb Space Telescope (JWST) sunshield is a passive thermal control system deployed post-launch to shield the telescope and instrumentation from the light and heat of the Sun, Earth, and Moon. By keeping the telescope and instruments in permanent shadow, it allows them to cool to their design temperature of 40 kelvins (−233 °C; −388 °F). Its intricate deployment was successfully completed on January 4, 2022, ten days after launch, when it was more than 0.8 million kilometers (500,000 mi) away from Earth.[1][2]