Agreed. It really would be something to see. Odds are probably against us, though. {{sigh}}
We only see Orion in the winter. If it happens in the summer time, would we see it at all?
And now i’ve got Bruce Cockburn’s “When the Sun Goes Nova” running through my head.
If the supernova is bright enough to be seen in the daytime yes, we would see it in summer. It’s still there, we just can’t see it for the same reason we can’t see other stars in the daytime.
I hope it already happened, close to 640 years ago. I’ve got places to go, and a finite amount of pie.
How suddenly does such an event happen? Does a star just abruptly go kablooie over a span on, say, one hour? Or one week? Or one year? Or one hundred years?
Orion is a ‘winter’ constellation in that it only rises at night in winter in the northern hemisphere. During winter Orion is on the same side of the sun as we are, so at night when we are facing away from the sun it appears in the night sky. In summer Orion on the other side of the Sun, so the only time it is in our field of view is during the daytime.
A Betelgeuse supernova would be bright enough to see during the daytime, just as the moon is. But it would be really spectacular at night.
Betelgeuse has always been kind of explody, but you know it is a variable star, right?
How long it takes… do you mean the actual core collapse? Milliseconds? You don’t want to be around, let’s say.
Not quite milliseconds: the outer part of the core collapses at up to 70000 km/s. But then it blows…
There are a variety of types of supernovas*. Details vary. But within a few seconds a huge percentage of remaining fussionable material does just that. Due to intense radiation and heat a lot of stuff keeps doing it’s glow thing for a while, but the big excitement is over.
- Sorry, but I was born slightly after the Roman Empire collapsed.
Orion is visible at some time during the night through most of the year. We only consider it a “winter” constellation because in the northern hemisphere, winter coincides when Orion happens to be up through most of the night. Most other times of the year except for around June-July you can catch Orion while it’s dark out but it might be some inconvenient time in the morning before it rises.
It seems to me that there is a general misunderstanding about what *now *means in relativistic terms among the participants: the 640 (light-)years are irrelevant. *Now *is when we see it, there is no absolute time in the Universe out there. We don’t know and can’t know anything before we can measure it, and we can’t measure it before the signal arrives. But when the signal arrives, I want to look up. I hope it will be amazing. And fast in its development. I think it will be a joy to watch.
Right. As if the mere fall of a continent-spanning empire is a valid reason to give up on the rules of grammar. {{pffft}}
Which really puzzles me about an alleged supernova sighted in 1006, which was visible for about two weeks.
The months long thing is for an observer in the ~immediate vicinity. An observer quite far off will only see the very peak brightness which might last a few days. (But said observer with a good telescope will see it for longer.)
The inverse-square law applies to supernovas.
But aren’t all Earth-bound observers the same distance from a supernova?
I believe that ftg was talking about hypothetical observers around stars closer to the supernova than Sol.
Not all supernovas are the same distance from Earth-bound observers.
According to the Wiki article, the Big B is a variable star and normally varies from about 0.00 to +1.3 (faintest). Each order of stellar magnitude, by definition, is 2.5 so at the bottom of its normal variation it’s already more than twice as faint as when it’s at its brightest.
So what I’d l like to know now is just how faint Betelgeuse is at the moment. What is the current magnitude?
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Good point, but a minor nitpick: The logarithmic magnitude scale is based not on 2.5, but on 2.5118… (the fifth root of 100), so magnitude 5 is 100x dimmer than magnitude 0. The reason for this odd choice is historical. The magnitude scale is more than 2000 years old and originally had no precise mathematical definition. In the 19th century the modern definition was introduced to approximately match the historical magnitudes.