You might be wondering why I haven’t jumped on the Betelgeuse “dimming” bandwagon and yelled from the roof top “The sky is falling!” err sorry, “Betelgeuse is about to go supernova!” Well, I decided to tap the brakes and take a wait and see approach. At least for a little bit. Often these types of reports travel at the speed of light only to fizzle out leaving people to later ask “Hey, whatever became of that star that they said dimmed a little bit, and might even explode?”
The reality is Betelgeuse is destined to go supernova and astronomically speaking it’s due to happen pretty soon. Betelgeuse is a red supergiant star and starting back in October of last year the star noticeably dimmed in brightness, thus far by a factor of 2.5 from magnitude +0.5 to +1.5. This is not totally out of the realm of possibility since Betelgeuse is a variable star whose brightness fluctuates from +0.0 to +1.3 but it was enough for astronomers to sit up and take notice.
The star is 650 to 700 light years from Earth, the second brightest star in the constellation Orion behind Rigel and is the 11th brightest star in the night sky. As luck would have it Orion is perfectly placed these February nights for you to step out after dark, and if you are in the U.S., face south. You’ll find Orion fairly high in the southeast and crossing the meridian around 9 p.m.
Betelgeuse is a high mass star meaning it’s a large star. If it were to replace our Sun it would envelop all the inner planets, the asteroid belt and probably Jupiter too. Large mass stars burn their fuel faster and are thus short-lived. The life span of a star like Betelgeuse is measured in millions of years where a star like our Sun is measured in billions of years.
Betelgeuse has been gobbling up it’s fuel for millions of years. Through nuclear fusion it first converted hydrogen to helium then it started burning the helium into heavier elements. That process can’t continue forever, and in it’s own time Betelgeuse will end its life thus resulting in an epic chain reaction explosion, a supernova. The big question everybody wants to know of course is when? It could be next Tuesday or 100,000 years from now. Just so we’re clear, 100,000 years is a drop in the bucket if we reference the cosmic timeline where the universe is 13.8 billion years old but decidedly that’s a looong time to you and me.
Betelgeuse going supernova would be a world-wide astronomical event for the ages. Oddly, the first signs of it actually going supernova would not be it brightening visually in the sky. Earth would first be flooded with neutrinos from the blast which would be picked up by observatories (detectors). Soon after the neutrino volley over a few hours the star will brighten eventually to the brightness of a full moon. It will be visible in the day time, and other than the Sun will dominate our sky. Thankfully, the star is far enough away that the blast should not pose any danger to us.
Day in and day out, as most people go about their lives the night sky seems pretty static to them. They might notice the Moon occasionally but most don’t pay much attention. They are engrossed in their routines and important stuff like who’s going to be selected and eventually win Dancing With The Stars this season?
Should Betelgeuse go supernova in our lifetimes it will be an amazing sight that will captivate the world. Visible for months after it’s initial brightening, it will be studied vigorously by astronomers. At its brightest it will mimic a full moon and will undoubtedly influence so many aspects of our lives, just as this type of event has done in the past. In the past? Yes, supernova have been recorded throughout the ages by many ancient cultures and civilizations including the Arabs, Chinese and Greeks.
In more recent history most of the supernova events have not been as brilliantly bright in our sky as would Betelgeuse going supernova, but should that happen it would certainly serve as a stark example of how dynamic and powerful the universe we reside in can be.
Clear Skies,