Amazing images
Cassiopeia A’s ‘Green Monster’
8 January 2024
© NASA
The bizarre wisp of green light dubbed the Green Monster, first seen last year snaking through the glowing remnants of an exploded star, belongs to a blast wave bordering the debris field, a new study reveals. Last April, NASA’s James Webb Space Telescope photographed the unusual wall of emission in front of Cassiopeia A, or Cas A, an expanding shell of hot gas roughly 11,000 light years from Earth whose light first reached us 340 years ago. For the past year, astronomers have been trying to explain its origin and presence in the wellstudied supernova remnant.