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Cassiopeia A Close-ups (NIRCam Image)

The image is split into 5 boxes. A large image at the left-hand side takes up most of the image. There are four images along the right-hand side in a column, labeled 1, 2, 3, and 4. The 4 images in the column are zoomed-in areas of the larger square image on the left. The image on the left has a circular-shaped cloud of gas and dust with complex structure, with an inner shell of bright pink and orange filaments that look like tiny pieces of shattered glass. A zoom-in of this material appears in the box labeled 1. Around the exterior of the inner shell in the main image there are wispy curtains of gas that look like campfire smoke. Within the cavity of the inner shell, there are small circular bubbles outlined in white. Box 2 is a zoom-in on these circles. Scattered outside the nebula in the main image, there are also clumps of yellow dust. Boxes 3 and 4 are zoomed-in areas of these clumps. Box 4 highlights a particularly large clump at the bottom right of the main image that is detailed and striated.

This image highlights several interesting features of supernova remnant Cassiopeia A as seen with Webb’s NIRCam (Near-Infrared Camera):

  1. NIRCam’s exquisite resolution is able to detect tiny knots of gas, comprised of sulfur, oxygen, argon, and neon from the star itself. Some filaments of debris are too tiny to be resolved even by Webb, meaning they are comparable to or less than 10 billion miles across (around 100 astronomical units). Researchers say this represents how the star shattered like glass when it exploded.
  2. Circular holes visible in the MIRI image within the Green Monster, a loop of green light in Cas A’s inner cavity, are faintly outlined in white and purple emission in the NIRCam image—this represents ionized gas. Researchers believe this is due to the supernova debris pushing through and sculpting gas left behind by the star before it exploded.
  3. This is one of a few light echoes visible in NIRCam’s image of Cas A. A light echo occurs when light from the star’s long-ago explosion has reached, and is warming, distant dust, which is glowing as it cools down.
  4. NIRCam captured a particularly intricate and large light echo, nicknamed Baby Cas A by researchers. It is actually located about 170 light-years behind the supernova remnant.

About the Object

  • R.A. Position
    R.A. PositionRight ascension – analogous to longitude – is one component of an object's position.
    23:23:24.00
  • Dec. Position
    Dec. PositionDeclination – analogous to latitude – is one component of an object's position.
    +58:48:54.00
  • 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.
    11,090 light-years
  • Dimensions
    DimensionsThe physical size of the object or the apparent angle it subtends on the sky.
    Main image is about 5.8 arcminutes across (19 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: 1947 (D. Milisavljevic).

    Image Processing: Alyssa Pagan (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.
    05 November 2022
  • Filters
    FiltersThe camera filters that were used in the science observations.
    F162M, F356W, F444W
  • Object Name
    Object NameA name or catalog number that astronomers use to identify an astronomical object.
    Cassiopeia A; SNR G111.7-02.1
  • Object Description
    Object DescriptionThe type of astronomical object.
    Supernova remnant
  • Release Date
    December 10, 2023
  • Science Release
    NASA’s Webb Stuns With New High-Definition Look at Exploded Star
    Read the release
  • Credit
    Image: NASA, ESA, CSA, STScI, Danny Milisavljevic (Purdue University), Ilse De Looze (UGhent), Tea Temim (Princeton University)

Downloads

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The image is split into 5 boxes. A large image at the left-hand side takes up most of the image. There are four images along the right-hand side in a column, labeled 1, 2, 3, and 4. The 4 images in the column are zoomed-in areas of the larger square image on the left. The image on the left has a circular-shaped cloud of gas and dust with complex structure, with an inner shell of bright pink and orange filaments that look like tiny pieces of shattered glass. A zoom-in of this material appears in the box labeled 1. Around the exterior of the inner shell in the main image there are wispy curtains of gas that look like campfire smoke. Within the cavity of the inner shell, there are small circular bubbles outlined in white. Box 2 is a zoom-in on these circles. Scattered outside the nebula in the main image, there are also clumps of yellow dust. Boxes 3 and 4 are zoomed-in areas of these clumps. Box 4 highlights a particularly large clump at the bottom right of the main image that is detailed and striated.
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:   Blue: F162M, Green: F356W, Red: F444W

Related Images & Videos

Cassiopeia A, a circular-shaped cloud of gas and dust with complex structure. The inner shell is made of bright pink and orange filaments studded with clumps and knots that look like tiny pieces of shattered glass. Around the exterior of the inner shell, particularly at the upper right, there are curtains of wispy gas that look like campfire smoke. The white smoke-like material also appears to fill the cavity of the inner shell, featuring structures shaped like large bubbles. Around and within the nebula, there are various stars seen as points of blue and white light. Outside the nebula, there are also clumps of yellow dust, with a particularly large clump at the bottom right corner that appears to have very detailed striations.

Cassiopeia A (NIRCam Image)

A new high-definition image from NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera) unveils intricate details of supernova remnant Cassiopeia A (Cas A), and shows the expanding shell of material slamming into the gas shed by the star before it exploded. The most...

A comparison between two images, one on the left (labeled NIRCam), and on the right (labeled MIRI), separated by a white line. Both are a square image rotated clockwise about 45 degrees, with solid black in the top left, top right, bottom left, and bottom right corners. On the left, the image is a circular-shaped cloud of gas and dust with complex structure. The inner shell is made of bright pink and orange filaments that look like tiny pieces of shattered glass. Around the exterior of the inner shell are curtains of wispy gas that look like campfire smoke. The white smoke-like material also fills the cavity of the inner shell, with structures shaped like large bubbles. Outside the nebula, there are also clumps of yellow dust. On the right, is the same nebula in different light. The curtains of material outside the inner shell glow orange instead of white. The inner shell looks more mottled, and is a muted pink. At center right, a greenish loop extends from the right side of the ring into the central cavity.

Cassiopeia A (NIRCam and MIRI side by side)

This image provides a side-by-side comparison of supernova remnant Cassiopeia A (Cas A) as captured by NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument). At first glance, Webb’s NIRCam image appears less colorful than the MIRI...

An image labeled “James Webb Space Telescope, Cassiopeia A, SNR G111.7-02.1.” The image has a circular-shaped cloud of gas and dust with complex structure. The inner shell is made of bright pink and orange filaments that look like tiny pieces of shattered glass. Around the exterior of the inner shell there are curtains of wispy gas that look like campfire smoke. The white smoke-like material also appears to fill the cavity of the inner shell, featuring structures shaped like large bubbles. Around and within the nebula, there are various stars seen as points of blue and white light. Outside the nebula, there are also clumps of yellow dust. At lower left, a white arrow pointing in the 2 o’clock direction is labeled N for north, while an arrow pointing in the 10 o‘clock direction is labeled E for east. At lower right, a scale bar is labeled 3 light-years and 1 arcminute. At the bottom is a list of MIRI filters in different colors, from left to right: F162M (blue), F356W (green), and F444W (red).

Cassiopeia A (NIRCam Compass Image)

This image of the Cassiopeia A supernova remnant, captured by Webb’s NIRCam (Near-Infrared Camera) shows compass arrows, scale bar, and color key for reference. The north and east compass arrows show the orientation of the image on the sky. The scale bar is labeled in...

Cassiopeia A, a circular-shaped cloud of gas and dust with complex structure. The inner shell is made of bright pink and orange filaments studded with clumps and knots that look like tiny pieces of shattered glass. Around the exterior of the inner shell, particularly at the upper right, there are curtains of wispy gas that look like campfire smoke. The white smoke-like material also appears to fill the cavity of the inner shell, featuring structures shaped like large bubbles. Around and within the nebula, there are various stars seen as points of blue and white light.

Take a Tour of Cassiopeia A

This video tours Webb’s NIRCam (Near-Infrared Camera) image of supernova remnant Cassiopeia A (Cas A). NIRCam’s high resolution detects tiny knots of gas leftover from the star’s explosion, as well as light echoes scattered across the field of view.

Telescope image including distant stars is overlaid with a semi-transparent graphic representing the constellation Cassiopeia, the queen. Thin blue lines in the outline of a “W” connect the actual stars of the constellation.

Cassiopeia A Zoom

This zoom-in video shows the relative location of supernova remnant Cassiopeia A (Cas A) on the sky. It begins with a ground-based photo by the late astrophotographer Akira Fujii. As it zooms into smaller portions of the sky, it fades into an image from the Digital Sky Survey....

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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, Danny Milisavljevic (Purdue University), Ilse De Looze (UGhent), Tea Temim (Princeton University)

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