The James Webb Space Telescope will give us our first true image of alien worlds

It's coming.

The James Webb Space Telescope will take us from the closest mysteries in our own solar system to the closest we've ever come to the origin of our universe. But in the middle lies the future of human society. If we survive the century, humans may settle other strange new worlds beyond our quaint neighborhood.

So it's time to reveal what the James Webb Space Telescope will reveal when its science missions target its instruments at alien worlds beyond our solar system.

So pack your bags, or be left behind.

The James Webb Space Telescope will reveal a wide diversity of worlds

In the last 30 years, astronomers have uncovered more than 5,000 exoplanets — alien worlds beyond our solar system. And, incredibly, they range in size, temperature, and mass, orbiting an unspeakably diverse variety of stars. This means the menu of worlds is lengthy.

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"With its powerful spectroscopic and imaging capabilities across a wide infrared wavelength range, Webb is poised to revolutionize our knowledge of the composition of these worlds and of planet-forming disks," said Knicole Colón, the deputy project scientist for Webb's exoplanet science, in a NASA blog post. "From small, potentially rocky exoplanets up to giant, gaseous ones, Webb will observe these worlds with the transit technique. Direct imaging techniques will be used to study young, giant exoplanets along with the environments in which planets form and evolve around stars, known as protoplanetary disks and debris disks."

Webb's NIRSpect instrument will help scientists detect thermal light on alien worlds

One of the most crucial kinds of observations the James Webb Telescope will carry out during its missions involves the study of an exoplanet's orbit. This is significant because it'll reveal enough data to examine the planet's atmospheric composition and dynamics. Colón is "involved in a program to observe the gas giant HD 80606 b as part of Webb’s first year of observations. Because the orbit of HD 80606 b is extremely eccentric (non-circular) and long (111 days), the amount of energy received by the planet from its star ranges from approximately 1 to 950 times what Earth receives from the Sun!"

"This results in extreme temperature variations, which are predicted to cause clouds to rapidly form and dissipate in the planet’s atmosphere on very short timescales," added Colón in the NASA post. Her science team will examine the cloud dynamics in real-time over a continuous, roughly 18-hour period — specifically for HD 80606 b while it swings behind its host star. And, using Webb's NIRSpec instrument, the team will analyze thermal light from the alien world's atmosphere.

The James Webb Space Telescope could detect Earth 2.0

"Beyond gas giants, a number of Webb’s exoplanet targets in its first year of observations are small and orbit stars that are smaller and cooler than the Sun, known as M dwarfs," added Colón. "While exoplanet discovery began around 30 years ago, many of these small exoplanets around M dwarfs were just discovered in the last few years by surveys like TESS."

As the James Webb Space Telescope continues in its mission, a wide spectrum of small planet atmospheres could reveal signs of molecules essential to life — like methane, carbon dioxide, and (of course) water. M dwarf stars are usually more active than our sun, with energetic stellar flares that pose a serious risk to their host worlds. With such high levels of energy, the flares can strip planetary atmospheres away, which means some of these worlds could be barren husks of a once thriving ecosystem. There's much to admire about the James Webb Telescope and what it promises for science, but the most relatable takeaway is this: In the coming years, we could find Earth 2.0 — where our descendants will one day live, laugh, and look back at their homeworld, far, far away.