Waiting for a supernova

If you recall seeing a very bright red star in the night sky last winter, like a glittering ruby, the likelihood is extremely high that what you saw was Betelgeuse - the bright top 'left' star in the constellation Orion. You can probably just about catch it in the early evening this time of the year, somewhere to the west, just before it sets below the horizon. And you'd probably not need a telescope to pick it out as the rich red hue of Betelgeuse is quite visible even to the naked eye.

On a telescope, the flashing red is even more evident, as seen in this video I took last winter, and in the single frame image I extracted from the video.

The reason that Betelgeuse is so red is because it is a red supergiant sun that is experiencing its final death throes. Betelgeuse (most people pronounce it 'Beetle-Juice', though Patrick Moore insists it's more like 'Bettle-Gerz') is one of the largest known stars and is probably at least the size of the orbits of Jupiter around the sun. That's a diameter about 700 times the size of our Sun or over 600 million miles. And the more massive a star, the shorter its lifespan. Red supergiants are the rock stars of the Universe - they live fast and die young. Astronomers think Betelegeuse is at the very end of its life and will go supernova soon.

You can imagine what size explosion something 700 times the size of our son will produce. A supernova is a titanic event that is among the most violent in the Universe. The Crab Nebula below was formed as the result of a sun going supernova (and the explosion was actually seen and documented by Arab, Chinese and Japanese astronomers in the year 1054). The nebula has a diameter of 11 light years (that's 700,000 times the distance between the Earth and the Sun) and it's still expanding today at a rate of about 1,500 kilometers per second. (This picture, by the way, is from the Hubble Space Telescope - not my puny 80mm refractor!)

So are we Earthlings going to be engulfed in seering heat, lethal gamma rays and deadly radioactive particles when Betelgeuse explodes any day now? Probably not.

For one thing, when I said that Betelgeuse is at the end of its life and will go supernova soon, "soon" in cosmic terms here may mean Betelgeuse might blow up tonight, or it might go boom 100,000 years from now or it might be a million years from now. Astronomers just aren't sure - a million years is a very short time in terms of a star's life span.

Another thing that may reassure you is that it may look very bright and close by but Betelgeuse is really quite far away. More than 600 light years away, in fact. That’s almost 4,000,000,000,000,000 miles. That's a long, long way away. And astronomers have estimated that a supernova would have to be within at least 50 light-years of Earth for it to harm us.

And. for all we know. Betelgeuse may well have already been blown to bits - and we still don't know about it. Betelgeuse is 600 light years away from us, which means it takes light 600 years to reach us from Betelgeuse. The Betelgeuse I saw in my scope is what Betelgeuse looked like 600 years ago - for all we know, it might no longer be there at this very moment!

While it may be harmless to Earth, a Betelgeuse supernova would be a breath-taking sight to see. Betelgeuse would brighten over the course of a fortnight until it would outshine the Moon. It would probably still be smaller in size than the moon and look like the picture below (compare that to my picture of the Orion constellation above). The supernova would also be visible during the day. It would stay at that brightness for a couple of months before dimming rapidly over a few days until it would not be visible to the naked eye (though a small nebula might result that could be viewed in a telescope).

Now, that would probably be the most astounding sight that any astronomer would behold in his or her lifetime. So every time I'm out observing, I almost always unconsciously give a quick glance to Betelgeuse, waiting for a supernova. Like I said earlier - you'll never know when it's going to happen.

And I really, really want  to see it go boom. Even if that means the complete obliteration of Betelgeusian civilization. Sorry!