Water Vapor in Distant Solar System. Credits: NASA, ESA, CSA, J. Olmsted (STScI).

Webb Spots Water Vapor in Distant Solar System

The James Webb Space Telescope, operated by NASA, has successfully identified water vapor at distances within 100 million miles from a star. This particular region is of great interest as it is where rocky, terrestrial planets have the potential to form.


In another sensational discovery, the James Webb Space Telescope spots water vapor in a distant solar system, dubbed PDS 70.

In the quest to unravel how water, an essential element for life, reaches Earth, scientists may have discovered crucial clues from an unlikely source: the planetary system PDS 70, situated 370 light-years away. The system, composed of both an inner and outer disk of gas and dust along with two known gas-giant planets, could potentially inform our understanding of how water might also find its way to rocky exoplanets far beyond our solar system.


Water Vapor in PDS 70: A Hint of Rocky Planet Formation?

In an astonishing feat of space exploration, NASA’s James Webb Space Telescope’s MIRI (Mid-Infrared Instrument) has detected water vapor within the system’s inner disk, specifically in areas less than 100 million miles from the star – a region believed to be ripe for the formation of rocky, terrestrial planets. This landmark discovery marks the first time water has been detected in a region known for hosting two or more protoplanets.

“Water has been observed in other disks, but this is the first time we’ve detected it so close to a star in a system where planets are in the process of forming. Webb made this unique measurement possible,” Giulia Perotti of the Max Planck Institute for Astronomy (MPIA) in Heidelberg, Germany, and lead author of the study, explains.

Thomas Henning, MPIA director and a co-author of the study, adds, “This discovery is thrilling as it explores the region where rocky planets akin to Earth typically form.”

Webb: Water Vapor in Distant Solar System

PDS 70, a K-type star, is cooler and estimated to be 5.4 million years old, making it relatively old for a star with planet-forming disks. This made the water vapor discovery all the more surprising.


Over time, the gas and dust content in planet-forming disks tend to decline, either blown away by the central star’s radiation and winds or coalescing into larger objects that eventually become planets. As water has previously gone undetected in the central regions of disks of a similar age, astronomers believed it might not withstand harsh stellar radiation, leading to dry environments for any potential rocky planets.

Still, No Planets

While no planets have yet been detected forming within PDS 70’s inner disk, the raw materials for building rocky worlds, such as silicates, are present. The detection of water vapor suggests that any rocky planets forming there would have water available from the outset.

Rens Waters of Radboud University in The Netherlands and a co-author of the study explains, “The inner disk is an exciting place with a high amount of small dust grains. Along with our water vapor detection, it’s a hotspot for potential planet formation.”

The Origins of Water in PDS 70: A Mystery to Unravel

The discovery prompts questions about the source of the water. The MINDS team have proposed two possibilities: either water molecules are forming where they’ve been detected via a combination of hydrogen and oxygen atoms, or ice-coated dust particles are being transported from the outer disk to the inner disk, where the water ice evaporates and turns into vapor. This latter theory is a surprising prospect, given that dust would have to traverse the vast gap carved out by the two giant planets.

Another enigma is how water could endure so close to the star when the star’s ultraviolet light should destroy any water molecules. Most likely, the surrounding materials such as dust and other water molecules are providing a protective shield, allowing the water in PDS 70’s inner disk to persist.


In the future, the research team plans to utilize two more of Webb’s instruments, NIRCam (Near-Infrared Camera) and NIRSpec (Near-Infrared Spectrograph), to further investigate the PDS 70 system and uncover more secrets about this fascinating distant world.

This groundbreaking discovery was part of Guaranteed Time Observation program 1282 and has been published in the journal Nature.

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Written by Ivan Petricevic

I've been writing passionately about ancient civilizations, history, alien life, and various other subjects for more than eight years. You may have seen me appear on Discovery Channel's What On Earth series, History Channel's Ancient Aliens, and Gaia's Ancient Civilizations among others.

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