Has it already happened?
Even for high-mass stars, the time it takes for a star to form from a molecular cloud is on the order of a million years (see Figs 5 and 6 of this paper). A human lifetime is essentially just a snapshot of this process; you’re not really going to see a new star form over such timescales (unless you count supernovae as “new stars”).
Also, all of the stars visible to the unaided eye are relatively close: only a few thousand light years away at most. All of the other stars in the milky way are too far away to see as anything more than a collective haze.
It has certainly happened. We know of stars that are younger than humans.
But has someone directly observed this happening? Well, it depends. As already noted, star formation takes a long time. It’s not like dark, cold dust suddenly collapses and ignites into a star. During the formation process, the dust is compressed, and as you might recall, as volume decreases on a mass, pressure and temperature increase. As it heats up, it starts emitting radiation. So it’s possible to observe this even before becoming a true main sequence star. And we have definitely observed a lot of those, and if you go outside and point your sufficiently powerful telescope in the right direction, you too can see one with your own eyes!
There’s not really one instant where a new star goes from not shining to shining where a human looking up at night would see a star “turn on.” The process of turning on takes between 10,000 - 1,000,000 years, depending on the size of the star and how many stages you include in the process.
Yes. New stars are still being born. We can also see stars going supernova that we couldn’t see with our bare eyes before.
Yes, it has already happened. When you look.up the sky, you are pretty much looking at ghosts. Due to the speed of light being finite.
Well yeah, but I mean has there been or could there be a time where someone actively looking at the sky sees a new star appear before their eyes and it wasn’t a super nova of a star dying or a newly formed star relatively nearby? IE the star has been there longer than Earth existed, but it is so far away it took until today to finally arrive where we could see it.
I know it has limited speed, but does it have a limited range before it would just always be invisible beyond a certain range based on size and luminosity, like a flashlight? I am ptetty sure atmosphere has something to do with that, but not 100% certain if light could travel in a vaccum forever.
We know of old supernovae because ancient astronomers catalogued them as new stars (nova means new). Maybe they also managed to find new stars.
The new Vera C. Rubin Observatory should help us with finding new stars and other objects. It will scan the whole southern night sky in three days, marking all changes when it gets to the same patch of sky again.
If sharks have a culture they might have recorded the appearance of Polaris, the north star. Sharks have been longer on earth than Polaris has existed.
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