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Comet 238P/Read (NIRCam Image)

In the center of a black image, a small glowing, hazy point glows white, surrounded by blue that trails off to the lower right.

This image of Comet 238P/Read was captured by the NIRCam (Near-Infrared Camera) instrument on NASA’s James Webb Space Telescope on September 8, 2022. It displays the hazy halo, called the coma, and tail that are characteristic of comets, as opposed to asteroids. The dusty coma and tail result from the vaporization of ices as the Sun warms the main body of the comet.

Comet Read was among three objects used to define the category of main belt comets in 2006. Before that, comets were understood to reside in the Kuiper Belt and Oort Cloud, beyond the orbit of Neptune, where their ices were preserved farther from the Sun. Since that time scientists have sought to confirm the presence of sublimating material in main belt comets, proving that their coma and tail were due to the same processes that other comets exhibit. With the detection of water vapor on Comet Read, Webb’s sensitive NIRSpec (Near-Infrared Spectrograph) instrument has achieved this goal. 

About the Object

  • Distance
    DistanceThe physical distance from Earth to the astronomical object. Distances within our solar system are usually measured in Astronomical Units (AU). Distances between stars are usually measured in light-years. Interstellar distances can also be measured in parsecs.
    Comet Read was 2.0897 au from JWST at the time of observation (about 300 million kilometers)

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: 1252 (M. Kelley)

  • Instrument
    InstrumentThe science instrument used to produce the data.
    NIRCam
  • Exposure Dates
    Exposure DatesThe date(s) that the telescope made its observations and the total exposure time.
    8 September 2022
  • Filters
    FiltersThe camera filters that were used in the science observations.
    F200W
  • Object Name
    Object NameA name or catalog number that astronomers use to identify an astronomical object.
    Comet 238P/Read, P/2005 U1
  • Object Description
    Object DescriptionThe type of astronomical object.
    Main-belt comet
  • Release Date
    May 15, 2023
  • Science Release
    NASA’s Webb Finds Water, and a New Mystery, in Rare Main Belt Comet
    Read the release
  • Credit
    Image: NASA, ESA, CSA, Mike Kelley (UMD); Image Processing: Henry Hsieh (PSI), Alyssa Pagan (STScI)

Downloads

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In the center of a black image, a small glowing, hazy point glows white, surrounded by blue that trails off to the lower right.
Color Info
Color InfoA brief description of the methods used to convert telescope data into the color image being presented.

This image is acquired by the NIRCam instrument on the James Webb Space Telescope. The color results from assigning a blue hue to a monochromatic (grayscale) image.

Compass and Scale
Compass and ScaleAn astronomical image with a scale that shows how large an object is on the sky, a compass that shows how the object is oriented on the sky, and the filters with which the image was made.

Related Images & Videos

Illustration, close up of rocky, potato-shaped body of a comet with detailed, cratered surface. Glowing rays emanate from the rocky surface like sunlight through clouds, representing water ice being vaporized by the heat of the Sun.

Artist's Concept of Comet 238P/Read

This illustration of Comet 238P/Read shows the main belt comet sublimating—its water ice vaporizing as its orbit approaches the Sun. This is significant, as the sublimation is what distinguishes comets from asteroids, creating their distinctive tail and hazy halo, or coma. It is...

Graph comparing the spectral data of Comet 238 P/Read and Comet 103 P/Hartley 2, highlighting the detection of water in both, and the absence of carbon dioxide in Comet Read. See extended description for full details.

Comet Spectra Comparison

This graphic presentation of spectral data highlights a key similarity and difference between observations of Comet 238P/Read by the NIRSpec (Near-Infrared Spectrograph) instrument on NASA’s James Webb Space Telescope in 2022 and observations of Comet 103P/Hartley 2 by NASA’s...

Header text reads James Webb Space Telescope, Comet 238 P/Read, P 2005 U 1. In the center of a black image, a small glowing, hazy point glows white, surrounded by blue that trails off to the lower right. At the bottom left are compass arrows indicating the orientation of the image on the sky. The north arrow points in the 12 o’clock direction. The east arrow points toward 9 o’clock. An arrow between them labeled To Sun points to 10 o’clock. At the lower right is a scale bar labeled 3,000 kilometers and 2,000 miles, which is roughly the length of the comet image shown above. Below the image is a color key showing the filter used to create the image and which visible-light color was assigned. Text reads NIRCam Filters, F200W in blue.

Comet 238P/Read (NIRCam Compass Image)

Image of Comet 238P/Read captured by the Webb Telescope’s NIRCam (Near-Infrared Camera), with compass arrows, scale bar, and color key for reference. The north and east compass arrows show the orientation of the image on the sky. Note that the relationship between north and east...

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Details

Last Updated
Aug 28, 2025
Contact
Media

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

Image Credit

NASA, ESA, CSA, Mike Kelley (UMD)

Image Processing Credit

Henry Hsieh (PSI), Alyssa Pagan (STScI)

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