A spectacular explosion became visible on Earth during the Middle Ages.
NASA/CXC/D. Berry; NASA/STSci/Hubble; ESA/M. Kornmesser
When stars die, some explode into supernovas and leave behind shimmering remnants — many of which we’ve observed via telescope.
It’s not easy to tell how long ago a supernova explosion began, but sometimes telescope records can illuminate the past.