In July 1054, Chinese astronomers recorded a ‘guest star’ in the constellation of Taurus. A ‘star’ never seen before had suddenly became brighter than all other stars in the sky
Visible in broad daylight
The ‘star’ was so bright that it was easily visible in broad daylight and one could even read by it at night, writes Carl Sagan in Cosmos. But it disappeared after some time. Where did it come from. Where did it go?
Gone with a bang
It wasn’t a new star. The bright object was a supernova—which can occur when a massive star runs out of fuel; its inner core blows up in a nuclear inferno. Our sun, which is not that massive, would never become a supernova. A grimmer fate awaits us
No more after 1604?
A supernova was observed in 1572, and described by astronomer Tycho Brahe. Another, in 1604, was described by Johannes Kepler. But no supernova explosion has been observed in our galaxy since the invention of the telescope
‘Invisible’ supernovas
They weren’t seen with optical telescopes as they occurred near the galaxy’s centre, an area clouded by dense gas and dust. But they leave other signatures. The galaxy’s youngest supernova explosion, around 110 years old, was identified recently using NASA’s Chandra X-ray Observatory