Here’s arguably the coolest video I’ve ever seen. The Hubble timelapse over 4 years of star V838 Monocerotis, or V838 Mon.
Captured over the course of 4 years by the Hubble Space Telescope, it’s a time-lapse that shows a very unusual star’s ‘light echo’ rippling out through space in the most spectacular fashion.
A light echo happens with any object in space that brightens very quickly, such as a nova or a supernova. The light from the star itself reaches us first, but if there is dust and other stellar debris around the star, some light is reflected from the clouds and takes a bit longer to reach us.