The Green Monster would have gotten away with it too, if it weren’t for these two meddling space telescopes 🔎⁣ ⁣ In April 2023, NASAWebb infrared data detected an unusual structure. It was dubbed the “Green Monster” because of its resemblance to the wall in the left field of Fenway Park. However, by combining the Webb data with X-rays from NASAChandraXray, researchers think they have hunted down the source of the Green Monster.⁣ ⁣ When a massive star exploded to create Cassiopeia A (aka Cas A) about 340 years ago, from Earth’s perspective, it created a ball of matter and light that expanded outward. The debris from the star is seen by Chandra because it is heated to tens of millions of degrees by shock waves, akin to sonic booms from a supersonic plane. Webb can see some material that has not been affected by shock waves, what can be called “pristine” debris. Much of this lies behind the Green Monster. The combination of Webb and Chandra data therefore gives a better idea of the total...