What Will the James Webb Space Telescope See?

... that no space telescope has explored before.

Webb’s infrared vision was designed to study every phase of more than 13.5 billion years of cosmic history — starting from about ~200 million years after the big bang, a time period we’ve never studied before.

In a process called cosmological redshifting, light is stretched from shorter wavelengths to longer wavelengths as the universe expands. That means light from the very first stars and galaxies reaches us as infrared light — which Webb specializes in!

The beautiful spiral and elliptical galaxies we’re familiar with did not always look this way. Not only can Webb analyze how galaxies form, interact, and change, but it will even be able to map out their composition and structure.

Stars and planets form in clouds of gas and dust. Visible light cannot penetrate these clouds, but infrared light can. As a demonstration, here’s the iconic “Pillars of Creation” taken by the Hubble Space Telescope in visible light...

...and here it is again in near-infrared light, also by Hubble. As you can see, a multitude of previously hidden stars were revealed! Webb’s capabilities will allow us to see infrared light from celestial objects in even greater clarity and sensitivity than Hubble.

... around other stars, or exoplanets. By analyzing the starlight that passes through an exoplanet’s atmosphere (a technique known as transit spectroscopy), Webb can tell us about the molecules and elements in its atmosphere. We could also learn about characteristics of the planet, including its color and weather!

Webb will study the atmosphere of Mars to gain insights into its past. It will also scan the atmospheres of the gas giants — Jupiter, Saturn, Uranus, and Neptune — to map their weather, temperature, and chemical structure.

Two of Webb’s targets, Jupiter’s moon Europa and Saturn’s moon Enceladus, are known as “ocean worlds” because scientists believe they may have liquid oceans beneath their surfaces. Webb will study the plumes of water that have been observed on their surfaces.

Webb will also see the unexpected and unknown...

Webb will unlock a rich treasure chest of infrared data. While scientists will point Webb at a variety of objects, Webb will also be able to discover things we can’t even imagine at the moment. What else do you think Webb will see?