> The one billion to be catalogued by Gaia is still only 1% of the Milky Way's total
I mean, wow. We are so tiny.
> The called-for specification was to get to know the brightest objects' coordinates down to an error of just seven micro-arcseconds. This angle is equivalent to the size of a euro coin on the Moon as seen from Earth.
It's amazing, and completely depressing at the same time. 1% of the stars in 0.00000000001% of all galaxies.
Totally out there thought of the day.
I'm hoping some day my atoms are reformed into another human in the much distant future, where we are technologically advanced to get something meaningful out of all of it.
Why don't you see that it's meaningful now? We didn't know about the galaxies only some 100 years ago. Now we know a lot even about how the universe started, read as an example, we will never see most of the first 500 million years, except on some places where the reionization process ended sooner:
"Instead of clusters and superclusters of galaxies, there will be… nothing. Dark energy will take care of that, driving all the other galaxies in the Universe, everything that isn’t bound to our local group, our beyond our visible horizon. Even the closest galaxies to us beyond the local group, like the Virgo Cluster, the Leo triplet, and even the extremely nearby M81 group will have redded out, and will leave no measurable signature behind."
"Even the leftover glow from the Big Bang would be undetectable! What appears now as a 2.725 Kelvin afterglow, with a relatively dense 411 photons-per-cubic centimeter, will look nothing like that 100 billion years from now."
Unfortunately the distance to even the nearest stars, makes travel to them unrealistic in any of our lifetimes. Sure we're getting new observational knowledge, but it's still depressing to think about the scale of the universe.
Yes, there may be more galaxies than stars in our milky way. But almost all of them are extremely far away and we will never have a chance to interact, or even visit them. Worse, the rate they are moving away from our galaxy/local cluster is accelerating. We have a bit time to study those galaxies before they fade into the eternal redshift, but the real interesting stuff, what at least has a decent chance to matter beyond pure curiosity is what Gaia observes.
Until they are so far redshifted that they fade into background noise. And the expansion of the universe is accelerating. We have a bit time to watch this spectacle, but the fate seems it is just our local cluster that will matter, for most of the time while stars generate heat. That is why I am not so keen on emphasising the billions and billions of galaxies. It's only a nice good-bye firework.
Edit: I still think there are much more galaxies in our universe than stars in our milky way: The universe must be bigger than our observable part and there is no reason to believe that it is much different there (read less or no galaxies) than where we happen to be. So the "eternal redshift" already happened for many galaxies (from mutual perspective).
I mean, wow. We are so tiny.
> The called-for specification was to get to know the brightest objects' coordinates down to an error of just seven micro-arcseconds. This angle is equivalent to the size of a euro coin on the Moon as seen from Earth.
This is quite an impressive feat of engineering!