Impressive photos from the ESA site: https://www.esa.int/Science_Exploration/Space_Science/Euclid...
First pictures from Euclid satellite reveal billions of orphan stars
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Re: First pictures from Euclid satellite reveal billions of orphan stars
#52The stars near us in the Milky Way are tens of light years away, and we’ll have to do some incredible science and technology to visit them. How much worse would it be if you were an intelligent life form on a planet orbiting one of those orphans, and the nearest star was a thousand, ten thousand, even a million light years away?
At some point, given the universe's expansion, galaxies will be moving away so fast that the observable universe will be just one galaxy. Already, the effective rate from galaxies far away is actually faster than the speed of light. Even at light speeds, we cannot reach 94% of them as we would never catch up if we left today. In cosmic scales of many billions of years, observers on every galaxy will eventually think…
The galaxies in our local group are gravitationally bound.
Re: First pictures from Euclid satellite reveal billions of orphan stars
#53The stars near us in the Milky Way are tens of light years away, and we’ll have to do some incredible science and technology to visit them. How much worse would it be if you were an intelligent life form on a planet orbiting one of those orphans, and the nearest star was a thousand, ten thousand, even a million light years away?
There is a novel written with that premise as the background! I can share the title with you, if you'd like - that particular premise is a very small part of the novel.
Re: First pictures from Euclid satellite reveal billions of orphan stars
#54Earlier quoted context omitted.
At some point, given the universe's expansion, galaxies will be moving away so fast that the observable universe will be just one galaxy. Already, the effective rate from galaxies far away is actually faster than the speed of light. Even at light speeds, we cannot reach 94% of them as we would never catch up if we left today. In cosmic scales of many billions of years, observers on every galaxy will eventually think…
The galaxies in our local group are gravitationally bound.
[deleted]
Re: First pictures from Euclid satellite reveal billions of orphan stars
#55Earlier quoted context omitted.
I suspect in any solar system, the mass of the non-stars are a rounding error compared to the whole system's mass.
> I suspect in any solar system, the mass of the non-stars are a rounding error compared to the whole system's mass. A brown dwarf orbiting a red dwarf would beg to differ.
Is the brown dwarf not considered a star? I don't know.
Re: First pictures from Euclid satellite reveal billions of orphan stars
#56The stars near us in the Milky Way are tens of light years away, and we’ll have to do some incredible science and technology to visit them. How much worse would it be if you were an intelligent life form on a planet orbiting one of those orphans, and the nearest star was a thousand, ten thousand, even a million light years away?
At some point, given the universe's expansion, galaxies will be moving away so fast that the observable universe will be just one galaxy. Already, the effective rate from galaxies far away is actually faster than the speed of light. Even at light speeds, we cannot reach 94% of them as we would never catch up if we left today. In cosmic scales of many billions of years, observers on every galaxy will eventually think…
> In cosmic scales of many billions of years, observers on every galaxy will eventually think that their galaxy is the only one that has ever existed.
Unless of course some of them manage to find ways to preserve information and keep records over those billions of years. The lost galaxies will be known from that.
Re: First pictures from Euclid satellite reveal billions of orphan stars
#57Re: First pictures from Euclid satellite reveal billions of orphan stars
#58Re: First pictures from Euclid satellite reveal billions of orphan stars
#59Earlier quoted context omitted.
> I suspect in any solar system, the mass of the non-stars are a rounding error compared to the whole system's mass. A brown dwarf orbiting a red dwarf would beg to differ.
Is the brown dwarf not considered a star? I don't know.
“A brown dwarf is an object which is made of the same stuff as stars, but does not have enough mass for hydrogen fusion (combining hydrogen atoms into helium atoms). Hydrogen fusion is what makes stars glow. Brown dwarfs are not massive enough to do this, so they are not stars. On the other hand, they are not regular giant planets, because they do glow.”
https://simple.wikipedia.org/wiki/Brown_dwarf
While very young they generate heat from both deuterium fusion but that only lasts millions to tens of millions of years. Energy from radioactive decay and their slow contraction lasts for much longer.
Re: First pictures from Euclid satellite reveal billions of orphan stars
#60Earlier quoted context omitted.
A lot of people outside of HN don't know what a trillion is.
Tell them it's comparable to $1 bills laid end to end from here to the sun. And tell them it's only 1/35 of the US national debt, which is roughly $350,000 per US taxpayer.
How many Olympic swimming pools is that?