NASA held a press conference today to announce the discovery of a discovery of the most recent supernova in our galaxy. The discovery was made by tracking the rapid expansion of its remains.
The supernova explosion occurred about 140 years ago, making it the most recent supernova in the Milky Way as measured in Earth's time frame. Previously, the last known galactic supernova occurred around 1680, based on studying the expansion of its remnant Cassiopeia A.
The tracking of this source began in 1985 when astronomers, led by David Green of the University of Cambridge, used the VLA to identify G1.9+0.3 as the remnant of a supernova explosion near the center of our galaxy. Based on its small size, it was thought to have resulted from a supernova that exploded about 400 to 1000 years ago.