In October of 1604, a brilliant “new” star blazed to life in the constellation Ophiuchus. It was bright enough to see in the daytime for weeks. German astronomer Johannes Kepler kept a close eye on it until it faded from the night sky, in 1606. So today, it’s known as Kepler’s Supernova. It’s the last known supernova in the Milky Way Galaxy.

A space telescope has been keeping a close eye on the aftermath of that event for the past 25 years. That’s revealed a lot about the supernova and the environment around it.

The supernova flared to life when a stellar corpse known as a white dwarf tipped above its weight limit. The star either stole gas from a companion star, or it merged with another white dwarf. Either way, the star was blasted to bits. The explosion expelled a huge cloud of debris – a nebula that today spans about a light-year. It’s extremely hot, so it produces a lot of X-rays.

Chandra X-Ray Observatory has taken many looks at the nebula. It’s found that one side of it is expanding at about two percent of the speed of light. The opposite side is moving only one-third that fast. The slower side is also hotter. That’s because it’s running into more gas and dust around the nebula.

Chandra will keep an eye on the nebula for as long as it can – telling us much more about the violent death of a star.

Script by Damond Benningfield