Betelgeuse Star.

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Continuing my current obsession with all things space, I'm now watching Ad Astra. Started off pretty well. Nice concept.
 


"I've tried to put this explosion into human terms and it's really, really difficult," co-author Melanie Johnston-Hollitt told BBC News.

"The best I can do is tell you that if this explosion continued to occur over the 240 million years of the outburst - which it probably didn't, but anyway - it'd be like setting off 20 billion, billion megaton TNT explosions every thousandth of a second for the entire 240 million years. So that's incomprehensibly big. Huge."

:eek:
 
^^^^ Ridiculous. It's all I can say to that. Comprehension isn't possible.
 
Dust clouds are to blame. Why is it that something cool happens in space and dust clouds are always there to spoil the fun!
 
If only a fraction of that energy could be captured.
Makes our fossil fuel, nuclear, wind and solar energy so insignificant.
 
If only a fraction of that energy could be captured.
Makes our fossil fuel, nuclear, wind and solar energy so insignificant.

Seeing the endless possibilities in outer space, is really awe-inspiring. We, however, are stuck in this system of complacency, where lobbying for "safer", more profitable options has bogged us down in a big way.
 
Yes, something completely out of our control will wipe us out. Enjoy life while you can!
 
I’ve always liked the ending to Men In Black. The way it depicts just how small we really are.

 
I agree! Of all the supernovae that have ever gone off, we're suck with this particular one because of it's convenient timing. For all we know, there must be some far off star system, where a star must be going nova every hour or so.
 
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I agree! Of all the supernovae that have ever gone off, we're suck with this particular one because of it's convenient timing. For all we know, there must be some far off star system, where a star must be going nova every hour or so.
~Engineer.AI
Every picosecond is probably closer to the truth.
 
Every picosecond is probably closer to the truth.

That's a really mind-blowing thought once you think about it. Betelgeuse will be there for another 10,000 years or so, meanwhile another system out there is enjoying a barrage of interstellar explosions from their cosmic backyard.
 
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There's about 1 supernova per millisecond in the observable Universe, and about 3 every microsecond in the entire Universe. Some estimates go as high as 10x that number.
 
How many have we observed?
As far as I can tell there are 39 supernovae in recorded history, the earliest being the year 185 by Chinese astronomers.

The earliest 10 were all in the Milky Way galaxy. The latest of these was in 1868, but not identified as a supernova until 1985.

The closest was the famous Crab Nebula in 1054, at 6,500 light-years. The furthest ever identified so far is 4.7bn light-years, in 2005. Light from that is as old as the Earth.

There have been none in the Milky Way since 1868, so statistically we're probably due for one.
 
As far as I can tell there are 39 supernovae in recorded history

Thanks - so what is the ELI5 for why there are 1000 per second in the observable universe but we have only observed 39 ever, which is a lot fewer by my back of an envelope calculation.
 
There's about 1 supernova per millisecond in the observable Universe, and about 3 every microsecond in the entire Universe. Some estimates go as high as 10x that number.
I think we need a large pinch of salt here. The estimates for the number of galaxies in the observable universe have risen from 100 billion through 200 billion to a current estimate of 2 trillion, which of course will be subject to many further revisions. The rate of production of various types of supernovae vary from one every two centuries to three or four per century per galaxy. Given these facts, to produce a figure to millisecond accuracy seems optimistic at best. As far as the "entire universe" is concerned, we have no idea how big it is (unknowable? Infinite?), microsecond accuracy is not remotely possible.
To answer some of @imightbewrong 'so questions as best I can:
All apart from one supernova detected in recent years have been extra-galactic. There are thousands. The most recent in our galaxy occurred about 140 years ago, detected by the Chandra telescope:
List of supernovae:
www.cbat.eps.harvard.edu/lists/Supernovae.html
www.rochesterastronomy.org/sn2019/snstats.html

The most distant supernova detected is at a distance of 10.5 billion light years:

 
Are you saying we have observed supernovae in other galaxies?
Oh, yes, absolutely. A supernova is pretty bright. For a few weeks it's nearly as bright as its galaxy. As I say, the remotest seen so far is 4.7 gigalightyears away. Our Galaxy is about 100,000 light-years across.
Thanks - so what is the ELI5 for why there are 1000 per second in the observable universe but we have only observed 39 ever, which is a lot fewer by my back of an envelope calculation.
Good question.

There are 200 billion galaxies in the observable universe, but most of them are at the limits of observation. So the chances of spotting one in a very distant galaxy is low. You must have seen the Hubble Deep Field Image:

Hubble Ultra-deep Field

That contains about 10,000 galaxies, in about 1/24,000,000th of the whole sky.

The chances of two successive images showing a galaxy which has brightened for a short while obviously depend on how far apart in time the two images are, and how easy it is to scan the picture. 10,000 galaxies will have about 100 supernovae a year between them, so that's one every 3-4 days. But pictures like the HDF are not taken every 3-4 days, at least not at the moment. That particular area of sky might never be photographed again, or at least not for many years.

Also, such major scans of the sky, even covering large areas per scan are pretty recent. I don't think it's a paradox that we've found so few supernovae in the past; but I think we can expect that to ramp up hugely in the future.
 
I think we need a large pinch of salt here. The estimates for the number of galaxies in the observable universe have risen from 100 billion through 200 billion to a current estimate of 2 trillion, which of course will be subject to many further revisions. The rate of production of various types of supernovae vary from one every two centuries to three or four per century per galaxy. Given these facts, to produce a figure to millisecond accuracy seems optimistic at best. As far as the "entire universe" is concerned, we have no idea how big it is (unknowable? Infinite?), microsecond accuracy is not remotely possible.
To answer some of @imightbewrong 'so questions as best I can:
All apart from one supernova detected in recent years have been extra-galactic. There are thousands. The most recent in our galaxy occurred about 140 years ago, detected by the Chandra telescope:
List of supernovae:
www.cbat.eps.harvard.edu/lists/Supernovae.html
www.rochesterastronomy.org/sn2019/snstats.html

The most distant supernova detected is at a distance of 10.5 billion light years:

One big apology here: I had no idea the numbers of observed supernovae was so high. The list I consulted must have been severely edited. Sorry. :blush:

In physics we have no real idea about anything. That doesn't mean we can't have a go at putting things into context. Even a big range of possibilities allows you to get a grasp of scales. I did say that some estimate are much different from my figures.
 
😯
Distance to earth is 642.5 light years, that's 3.774e+15 miles and it's radius is 617.1 million kilometres!😯🌏
Looks like it may be much ado about nothing:
 

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