Free Astronomy Magazine March-April 2022

9 MARCH-APRIL 2022 within and beyond. High-altitude observatories, such as the Infrared Telescope Facility in Hawaii, and very-high-altitude observatories, such as the flying Stratospheric Ob- servatory for Infrared Astronomy (SOFIA), are solutions to the prob- lem, but are limited compared to having an infrared telescope that is completely isolated from all nearby heat sources. The solution to all of Webb’s prob- lems is location, both in terms of the location of the telescope itself, as well as the placement of all onboard equipment capable of producing enough heat to set off the detectors. Joseph-Louis Lagrange identified five locations at which three bodies could exist at stable locations with respect to one another as they orbit. In these special cases of the famous “three-body problem” in physics, so- lutions work when two of the bodies are massive and the third is diminu- tive by comparison – a case for which the Sun-Earth-JWST combination certainly applies. At L2, JWST finds itself in a reasonably stable orbit with the Sun, Earth, and Moon all on one side of the telescope – meaning the sunshield can protect the on- board detectors from the heat being emitted or reflected from all three celestial bodies. At the other four La- grange points, JWST would either be T he trajectory followed by the James Webb Space Telescope to reach its special placement around the Lagrangian point L2. Distances are not to scale. [Matthew Twombly]