James Webb Space Telescope

The James Webb Space Telescope is the largest, most powerful space telescope ever built. It will allow scientists to look at what our universe was like about 200 million years after the Big Bang. The telescope will be able to capture images of some of the first galaxies ever formed. It will also be able to observe objects in our solar system from Mars outward, look inside dust clouds to see where new stars and planets are forming and examine the atmospheres of planets orbiting other stars. The James Webb Space Telescope sees the universe in light that is invisible to human eyes. This light is called infrared radiation, and we can feel it as heat. Firefighters use infrared cameras to see and rescue people through the smoke in a fire. The James Webb Space Telescope will use its infrared cameras to see through dust in our universe. Stars and planets form inside those dust clouds, so peeking inside could lead to exciting new discoveries! It will also be able to see objects (like the first galaxies) that are so far away that the expansion of the universe has made their light shift from visible to infrared! The Webb telescope’s cameras are sensitive to heat from the Sun. Just like you might wear a hat or a visor to block the Sun from your eyes, Webb has a sunshield to protect its instruments and mirrors. The telescope’s sunshield is about the size of a tennis court. The temperature difference between the sun-facing and shaded sides of the telescope is more than 600 degrees Fahrenheit! Space telescopes “see” by using mirrors to collect and focus light from distant stars. (Check out our telescopes page to learn more about how space telescopes work.) The bigger the mirror, the more details the telescope can see. It’s very difficult to launch a giant, heavy mirror into space. So, engineers gave the Webb telescope 18 smaller mirrors that fit together like a puzzle. The mirrors fold up inside the rocket, then unfold to form one large mirror in orbit. Why are the mirrors gold? A thin layer of gold helps the mirrors reflect infrared light! Our solar system isn’t the only home for planets! Scientists have discovered thousands of planets orbiting stars other than our Sun. These are called exoplanets. The James Webb Space Telescope will help to study the atmospheres of exoplanets. Could the atmospheres of some exoplanets hold the building blocks for life? We will find out soon! The James Webb Space Telescope (sometimes called JWST or Webb) is an orbiting infrared observatory that will complement and extend the discoveries of the James Webb Space Telescope, with longer wavelength coverage and greatly improved sensitivity. The longer wavelengths enable Webb to look much closer to the beginning of time and to hunt for the unobserved formation of the first galaxies, as well as to look inside dust clouds where stars and planetary systems are forming today.