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Explanation: Why is the image of Cassiopeia A changing? Two images of the nearby supernova remnant taken a year apart in infrared light appear to show outward motions at tremendous speeds. This was unexpected since the supernova that created the picturesque nebula was seen 325 years ago. The reason is likely light echoes. Light from the supernova heated up distant ambient dust that is just beginning to show its glow. As time goes by, more distant dust lights up, giving the appearance of outward motion. The above image is a composite of X-ray, optical, and infrared light exposures that have been digitally combined. The infrared light image was taken by the orbiting Spitzer Space Telescope and was used in the discovery of the light echo. Cassiopeia A spans about 125 light years and lies 10,000 light years away toward the constellation of Cassiopeia.
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NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: Cas A - infrared - supernova remnant
Publications with words: Cas A - infrared - supernova remnant
See also:
- APOD: 2024 September 18 Á The Mermaid Nebula Supernova Remnant
- APOD: 2024 April 16 Á Filaments of the Vela Supernova Remnant
- APOD: 2024 April 3 Á Unusual Nebula Pa 30
- APOD: 2024 March 25 Á Sonified: The Jellyfish Nebula Supernova Remnant
- APOD: 2024 February 27 Á Supernova Remnant Simeis 147
- The Pencil Nebula Supernova Shock Wave
- APOD: 2023 December 26 Á IC 443: The Jellyfish Nebula