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Cassiopeia A Light Echoes (NIRCam Images)

Three rows show Webb images of the same region taken on three different dates. The top row is labeled August 19, 2024. The middle row is labeled September 16, 2024. The bottom row is labeled September 30, 2024. Each row shows two images split by a vertical black bar where there is no data. Each image is speckled with dozens of white stars, some showing Webb’s signature 8-point diffraction spikes, against the black background of space. The images also show tightly packed, glowing red filaments that resemble muscle fibers or wood grain. While the background stars are the same in every row, the filaments change noticeably. In the top row, the filaments extend horizontally from upper left to lower right. In the middle and bottom rows, the filaments extend from lower left to upper right, and seem to shift slightly downward in position, with the last the lowest.

These shimmering cosmic curtains show interstellar gas and dust that has been heated by the flashbulb explosion of a long-ago supernova. The gas then glows infrared light in what is known as a thermal light echo. As the supernova illumination travels through space at the speed of light, the echo appears to expand. NASA’s James Webb Space Telescope observed this light echo in the vicinity of the supernova remnant Cassiopeia A three separate times, in essence creating a 3D scan of the interstellar material. Note that the field of view in the top row is rotated slightly clockwise relative to the middle and bottom rows, due to the roll angle of the Webb telescope when the observations were taken.

About the Object

  • R.A. Position
    R.A. PositionRight ascension – analogous to longitude – is one component of an object's position.
    23:16:03.93
  • Dec. Position
    Dec. PositionDeclination – analogous to latitude – is one component of an object's position.
    +58:22:31.59
  • Constellation
    ConstellationOne of 88 recognized regions of the celestial sphere in which the object appears.
    Cassiopeia
  • 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.
    About 11,000 light years

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: 5451 (J. Jencson). Image processing: Joseph DePasquale (STScI).

  • 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.
    August 19, September 16, and September 30, 2024
  • Filters
    FiltersThe camera filters that were used in the science observations.
    F200W, F300M, F335M, F360M, F444W
  • Object Name
    Object NameA name or catalog number that astronomers use to identify an astronomical object.
    Light Echoes from Cassiopeia A
  • Object Description
    Object DescriptionThe type of astronomical object.
    Light echoes from a supernova explosion
  • Release Date
    January 14, 2025
  • Science Release
    NASA’s Webb Reveals Intricate Layers of Interstellar Dust, Gas
    Read the release
  • Credit
    Image: NASA, ESA, CSA, STScI, Jacob Jencson (Caltech/IPAC)

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Three rows show Webb images of the same region taken on three different dates. The top row is labeled August 19, 2024. The middle row is labeled September 16, 2024. The bottom row is labeled September 30, 2024. Each row shows two images split by a vertical black bar where there is no data. Each image is speckled with dozens of white stars, some showing Webb’s signature 8-point diffraction spikes, against the black background of space. The images also show tightly packed, glowing red filaments that resemble muscle fibers or wood grain. While the background stars are the same in every row, the filaments change noticeably. In the top row, the filaments extend horizontally from upper left to lower right. In the middle and bottom rows, the filaments extend from lower left to upper right, and seem to shift slightly downward in position, with the last the lowest.
Color Info
Color InfoA brief description of the methods used to convert telescope data into the color image being presented.

These images are a composite of separate exposures acquired by the James Webb Space Telescope using the NIRCam instrument. Several filters were used to sample specific wavelength ranges. The color results from assigning different hues (colors) to each monochromatic (grayscale) image associated with an individual filter. In this case, the assigned colors are:   Red: F444W, Orange: F360M, Yellow: F335M, Green: F300M, Blue: F200W

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

A background image in a shade of orange shows cloud-like structures filling the field of view, along with a handful of stars. At the middle of the image is a bright circle with a white box around it. Lines extend from the box to the left, where an inset image shows a multicolored ring of gaseous filaments in shades of pink and purple. At lower right of the background image, two smaller regions have white boxes around them. Lines extend from those to boxes above with two insets. Each inset displays dozens of white stars on the black background of space. They also contain tightly packed, red filaments that resemble muscle fibers or wood grain.

Cassiopeia A Light Echoes (Spitzer Context)

This background image of the region around supernova remnant Cassiopeia A was released by NASA’s Spitzer Space Telescope in 2008 . By taking multiple images of this region over three years with Spitzer, researchers were able to examine a number of light echoes. Now, NASA’s James...

Image of light echoes in the vicinity of Cassiopeia A. Two images are separated by a vertical black bar where there is no data.

Cassiopeia A Light Echoes (Compass Image)

Image of light echoes near Cassiopeia A captured by Webb’s NIRCam instrument, 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 on the sky...

A few dozen white stars, some with Webb’s signature 8-point diffraction spikes, on the black background of space. Tightly packed, red-orange filaments extend horizontally from upper left to lower right, with a bulging upward curve on the right that is closer to the top. The filaments resemble wood grain. The image is labeled August 19, 2024 at bottom left.

Cassiopeia A Light Echoes Time-lapse

This time-lapse video using data from NASA’s James Webb Space Telescope highlights the evolution of one light echo in the vicinity of the supernova remnant Cassiopeia A. A light echo is created when a star explodes or erupts, flashing light into surrounding clumps of...

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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, STScI, Jacob Jencson (Caltech/IPAC)

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