How the James Webb Telescope will reveal the birth of alien worlds

We could find evidence of water, organic chemistry, and much more.
Brad Bergan
Webb in space (left), and an artistic rendering of a protoplanet (right).1, 2

We're not going to stop saying it.

The James Webb Space Telescope is going to change modern astronomy for keeps, in so many ways that it will outshine even the Hubble Space Telescope in scope and depth of discoveries and the advancement of science.

But a key objective for Webb's first year of science missions involves the pursuit and examination of alien worlds beyond our solar systems — specifically how they, and the potential for water and organic life, come into being, according to a blog post shared on NASA's official website.

The James Webb Space Telescope will reveal planet and star formations like never before

"In the first year of science operations, we expect Webb to write entirely new chapters in the history of our origins — the formation of stars and planets," said Klaus Pontoppidan, a scientist for Webb from the Space Telescope Science Institute, in the blog post.

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"It is the study of star and planet formation with Webb that allows us to connect observations of mature exoplanets to their birth environments, and our solar system to its own origins," added Pontoppidan. "Webb’s infrared capabilities are ideal for revealing how stars and planets form for three reasons: Infrared light is great at seeing through obscuring dust, it picks up the heat signatures of young stars and planets, and it reveals the presence of important chemical compounds, such as water and organic chemistry."

Near Infrared Horsehead Nebula
A near-infrared image of the Eagle Nebula's Pillars of Creation, captured by Hubble. This shows how infrared light can "sneak" through dense clouds of dust and gas. Source: NASA, ESA / Hubble / Hubble Heritage Team

Webb's MIRI can see through clouds 20 times thicker than Hubble's limit

Mid-infrared light (viewed via Webb's MIRI instrument) can move through clouds that are 20 times thicker than the ones visible light can penetrate. This is especially crucial for viewing young stars (which form relatively rapidly, sometimes in only 100,000 years), which are hidden away inside their natal clouds. These clouds haven't dispersed yet for young stars, which means we can't really see visible light.

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This is why Webb's infrared capabilities are central — allowing us to see, study, and comprehend the very beginning of star formation, when gas and dust are still collapsing inward, to give birth to baby stars.

But that's not all we'll find inside natal stellar clouds.

Simulated MIRI Spectrum
A simulated MIRI spectrum of a protoplanetary disk as it might look during several early science missions of Webb's. This spectrum shows water, methane, and several other chemicals. Source: NASA / STScI

We're going to see protoplanets at the very beginning of their evolution

"The second reason has to do with the young stars and giant planets themselves," continued Pontoppidan, in the blog post. "Both begin their lives as large, puffy structures that contract over time. While young stars tend to get hotter as they mature, and giant planets cool, both typically emit more light in the infrared than at visible wavelengths. That means that Webb is great at detecting new young stars and planets and can help us understand the physics of their earliest evolution."

"Previous infrared observatories, like the Spitzer Space Telescope, used similar techniques for the nearest star-forming clusters, but Webb will discover new young stars across the galaxy, the Magellanic Clouds, and beyond," added Pontoppidan.

"MIRI will also observe warm molecular gas near many young stars where rocky, potentially habitable planets may be forming," said Pontoppidan. Such observations will enable astronomers to finally build a consensus on the concentration of bulk molecules, including the beginnings of ice, "at the earliest stages of planet formation. It is no surprise that a significant number of Webb’s early scientific investigations aim to measure how planetary systems build the molecules that may be important for the emergence of life as we know it." If you can't wait, neither can we.

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