This is Cassiopeia A. Astronomers call it Cas A for short. It’s the youngest supernova remnant in the Milky Way and brightest extrasolar source of radio waves in our sky. This image – taken in X-rays by NASA’s CHANDRA X-ray Observatory – shows the debris field left behind after a massive star exploded. The explosion should have appeared in Earth’s sky over 300 years ago, but there are no historical records of any sightings of the supernova. One theory is that interstellar dust absorbed the visible radiation before it reached Earth.
New analysis shows that this supernova remnant acts like a relativistic pinball machine by accelerating electrons to enormous energies.
In this image, the blue, wispy arcs show where the acceleration is taking place in an expanding shock wave generated by the explosion. The red and green regions show material from the destroyed star that has been heated to millions of degrees by the explosion.
Eleanor Imster has helped write and edit EarthSky since 1995. She was an integral part of the award-winning EarthSky radio series almost since it began until it ended in 2013. Today, as Lead Editor at EarthSky.org, she helps present the science and nature stories and photos you enjoy. She also serves as one of the voices of EarthSky on social media platforms including Facebook, Twitter and G+. She and her husband live in Tennessee and have two grown sons.