"This suggests that the recent dramatic fading observed at visual wavelengths is due mostly to local surface phenomena, such as changes in dust extinction or molecular opacity along the line of sight through the inner wind and complex atmosphere, and/or surface temperature fluctuations."
Super disappointing. Is there still hope to see the supernova in our lifetime ?
Honestly, the best use of this the light delay fact is that you can annoy transient observers by trying to get SN1987A renamed to SN-1678900A or something.
At the distance from Earth to Betelgeuse?
It was, basically, a joke. Nothing you see through an optical telescope by eye is going to burn your retina off a star, excluding the one we orbit.
I did find my vision was degraded looking at Saturn in a 10" reflector: it is surprisingly bright. I was locally blind in the night light, after looking at the moon through binoculars.
I do not believe you can damage eyes because of reflected sunlight off planets or moons, through a telescope. If somebody can find a fresnel lens fire-starter for moonlight, I'll learn to smoke midnight cigars to light them.
But you definitely can suffer temporary light adaption loss, from the huge difference between what you see in the scope or binoculars, and what you see with full eyes, in the wide. It was 40 years ago, I wouldn't even know what kind of lens was on the eyescope. Saturn was maybe 1/5th of the visual field? Binoculars, 30x or 50x you're already looking at segments of the Moon, not the entire face I think.
Most of the possibility of it happening comes from the error bars in our assumptions about its progress through the red giant phase, and the error bars in our understanding of how red giants collapse. Put another way, it’s not that we think it might happen in our lifetimes, it’s that we’re relatively sure it won’t (but we could be wrong).
It is still more likely to occur in our lifetime than we would have guessed before--these sorts of dust-belching events are likely to happen right before the end. We just can't quantify that likelihood very well because this is the first time we've seen a (pre-)supernova in our stellar neighborhood in modern times.
Even at the oldest it is likely to be, under the best possible conditions for the shortest possible lifespan, it will still likely spend another 150,000 years as a red supergiant before it collapses.
So I don’t believe your statement to be true. We could be wrong about the mass of Betelgeuse. We could be wrong about its age, its chemical composition, its rate of rotation, etc. We could be wrong about our theories of how red supergiants evolve. Any or all of those could lead us to incorrectly conclude that Betelgeuse won’t go supernova in our lifetime. But by our current cosmological understanding, it’s not that “it could go tomorrow or a hundred thousand years from now”. It’s that we’re pretty sure it won’t go for over a hundred thousand years. But if we’re wrong, it’s technically possible that it could happen tomorrow.
So people run spectral synthesis codes of varying complexity, essentially simulating the entire star, and tweak the parameters to get good agreement between observed and simulated spectra.