The remnant known as G1.9+0.3 (shown here) came from the most recent supernova in our galaxy. To determine the age of the stellar explosion, astronomers tracked how quickly the remnant was expanding, by comparing a radio image from 1985 (blue) to an X-ray image taken in 2007 (orange). Credit: X-ray (NASA/CXC/NCSU/S.Reynolds et al.); Radio (NSF/NRAO/VLA/Cambridge/D.Green et al.)
