James Webb Space Telescope
Seeing the first galaxies in infrared. The James Webb Space Telescope launched on Christmas Day 2021 and sees the universe in infrared. Its gold mirror, sunshield and biggest discoveries.
Webb's primary mirror being tested: NASA/MSFC/David Higginbotham, Public domain
Hubble's infrared successor
The James Webb Space Telescope is the largest space telescope ever launched. It observes mainly in infrared light, which lets it see through dust clouds where stars form and catch the stretched light of the most distant galaxies, whose light has been travelling for more than 13 billion years.
Unfolding in space
Webb's 6.5-metre mirror was too large to fit in a rocket, so it was folded like origami. After launch on December 25, 2021, it unfolded its five-layer sunshield and mirror segments over several weeks in one of the most complex deployments ever attempted. The sunshield keeps the telescope at about minus 230 degrees Celsius so its own heat does not swamp faint infrared signals.
What Webb has seen
Webb has found galaxies that formed surprisingly early, only a few hundred million years after the Big Bang. It has measured the chemistry of exoplanet atmospheres, detecting carbon dioxide and other molecules, and has taken detailed images of Jupiter, Saturn, Uranus and Neptune with their rings and auroras.
Its images of star-forming regions, like the Pillars of Creation, have become some of the most recognised pictures in science.
Webb is not a replacement for Hubble but a partner. Hubble sees mostly visible and ultraviolet light, while Webb specialises in infrared, and many of the best recent results combine data from both telescopes.
A long life ahead
Webb sits near the Sun-Earth L2 point, about 1.5 million km away. Thanks to a very accurate launch, it saved fuel and could operate for well over a decade. Astronomers worldwide compete for observing time every year, so new discoveries are released constantly.
How to explore Webb's images
NASA, ESA and the Space Telescope Science Institute publish Webb's images with free high resolution downloads and plain-language explanations. Many images come in pairs, showing a target in near and mid infrared, which reveal different layers of dust and gas. Comparing Webb's view of a nebula with Hubble's visible-light picture is a great way to understand why infrared astronomy matters so much.
- Webb's primary mirror being tested: NASA/MSFC/David Higginbotham, Public domain
Text written by Planetinio.
