Orion image from winter 2019

Many click bait astronomy articles have surfaced claiming the star might be dimming due to its impending collapse and rebound as a supernova, but Betelgeuse is a known variable star and similar changes in its brightness have been noted in the past, although recent changes appear to deviate from established patterns.

Unusual gravitational waves have also been detected in the vicinity of the red supergiant, adding to the sense of mystery.  It’s important to note that these waves are merely in the vicinity, so could easily be generated by countless other sources behind Betelgeuse.

Still, it’s fun to speculate about the possibility of witnessing a relatively close supernova event in our lifetime.  The last two major naked eye supernovas were recorded in 1572 and and 1054, in Taurus (the Crab nebula) and Cassiopeia (Tycho Brahe supernova).  Both generated enough luminosity to be visible in daylight for several weeks, and shone as new ‘guest stars’ for around a year or so before fading.

Some work published by Dolan in 2016 estimated the impact of a Betelgeuse supernova on Earth and found it to be negligible.  At 500 light years distance the residual energy of the vastly expanded shockwave would be exponentially diminished as it passed Earth.  However the brightness predicted would be magnitude -12.4,  making such an event more luminous than a full Moon!

For the mathematically motivated I enclose an extract from his calculations below.