Cassiopeia A no longer the youngest supernova in Milky Way

Cassiopeia A has been famous for being the youngest supernova remnant in the Milky Way for a long time. That changed in 2008 with the discovery of G1.9+0.3 by Stephen Reynolds at North Carolina State University.

G1.9+0.3 is estimated to be 140 years old where as Cassiopeia A is estimated to be about 340 years old.  G1.9+0.3 is estimated to be roughly 26,000 light-years away whereas Cassiopeia A is around 11,000 light-years away.

Unfortunately, there are no historical records of either supernova being observed on Earth.  There was too much space dust to be able to see G1.9+0.3 when it occurred and the same reason might have been true for keeping Cassiopeia A from being observed.

Either way, there is a new youngest supernova in town for astronomers to get excited about.