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Interstellar Comet 3I/ATLAS (NIRSpec IFU)

Comparison of three telescope images side by side. They are roughly spherical but pixelated, with more intense color saturation in the center. From left to right: smallest sphere is blue and labeled H2O, orange is larger and labeled CO2, and red is largest and labeled CO. A scale bar at the lower left is labeled 1300 km/1 arcsecond and is about one fourth of each of the three images. A compass at the lower right shows north pointing up to 12 o’clock, east pointing left to 9 o’clock, and a fainter arrow labeled to Sun pointing down to 8 o’clock.

The NIRSpec (Near-Infrared Spectrograph) instrument on NASA’s James Webb Space Telescope can map specific chemical and molecular signatures, as seen here in its three images of comet 3I/ATLAS, each highlighting a part of the comet’s contents. 

Researchers use NIRSpec’s Integral Field Unit, which provides a spectrum of every image pixel, to dive deeper into the details of cosmic objects than they can with the telescope’s imaging instruments alone. This is crucial for a rare object like 3I/ATLAS, which is only the third comet from outside the solar system ever studied, and the first to be observed by an instrument capable of capturing as much detail as NIRSpec. With NIRSpec’s data, researchers can build a picture of where the comet may have come from and what its home system was like and then compare that to familiar conditions in the solar system. 

About the Data

  • Data Description
    Data DescriptionProposal: A description of the observations, their scientific justification, and the links to the data available in the science archive.
    Science Team: The astronomers who planned the observations and analyzed the data. "PI" refers to the Principal Investigator.

    This image was created with Webb data from proposal: 5094 (M.Cordiner)

  • Instrument
    InstrumentThe science instrument used to produce the data.
    NIRSpec
  • Exposure Dates
    Exposure DatesThe date(s) that the telescope made its observations and the total exposure time.
    06 Aug. 2025, 22-23 Dec. 2025
  • Filters
    FiltersThe camera filters that were used in the science observations.
    G325H, G395H
  • Object Name
    Object NameA name or catalog number that astronomers use to identify an astronomical object.
    Comet 3I/ATLAS
  • Object Description
    Object DescriptionThe type of astronomical object.
    Interstellar comet
  • Release Date
    June 22, 2026
  • Science Release
    NASA’s Webb Finds Clues to Ancient, Distant Origin of Comet 3I/ATLAS
    Read the release
  • Credit
    Image: NASA, ESA, CSA, STScI, Martin Cordiner (CUA, NASA-GSFC); Image Processing: Alyssa Pagan (STScI)

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Comparison of three telescope images side by side. They are roughly spherical but pixelated, with more intense color saturation in the center. From left to right: smallest sphere is blue and labeled H2O, orange is larger and labeled CO2, and red is largest and labeled CO. A scale bar at the lower left is labeled 1300 km/1 arcsecond and is about one fourth of each of the three images. A compass at the lower right shows north pointing up to 12 o’clock, east pointing left to 9 o’clock, and a fainter arrow labeled to Sun pointing down to 8 o’clock.
Color Info
Color InfoA brief description of the methods used to convert telescope data into the color image being presented.

These images were acquired by the NIRSpec IFU Instrument on the James Webb Space Telescope. The color results from assigning a color map to each monochromatic (grayscale) image. In this case, the assigned color is: Blue: H2O (2.55–2.90 microns), Orange/Yellow: CO2 (4.188–4.500 microns), Red: CO (4.50–4.85 microns)  

Related Images & Videos

Infographic showing differences in measured ratios of heavy carbon and heavy hydrogen between solar system comets and interstellar comet 3I/ATLAS. Title text reads Comet 3I/ATLAS, Composition Compared With Solar System Comets. Top portion of the infographic has headline Heavy Carbon, plus a horizontal scale in increments of 50 ranging from zero to 250 measuring the ratio of Carbon-12 to Carbon-13. Three solar system comets appear just below 100 on the scale, while 3I/ATLAS appears above 150 for carbon monoxide and about 170 for carbon dioxide. nBottom portion of infographic has headline Heavy Hydrogen and a horizontal scale ranging from 10 to the negative fifth power on the left to approximately 10 to the negative first power on the right, though 10 to the first is not labeled. This scale is labeled Ratio of Heavy Hydrogen Measured in Water. Eleven solar system comets appear on the graph, all falling to the right of 10 to the negative fourth power. Comet 3I/ATLAS appears at 10 to the negative second power.

3I/ATLAS Compared to Solar System Comets

These graphs lay out the significant difference in composition between the interstellar comet 3I/ATLAS and comets originating in our solar system. This very specific data helps researchers build a picture of the comet’s original planetary system.

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Details

Last Updated
Jun 22, 2026
Location
NASA Goddard Space Flight Center
Contact
Media

Laura Betz
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
laura.e.betz@nasa.gov

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