“Which is quite a lot and would ruin your appetite if you ate a whole one.”
Yeah, but the fun size ones are too small
Chinese scientists have estimated the mass of the Milky Way. To do so the authors considered 260,000 stars – a larger number than has previously been used for a study of this type – many of them identified by the European Space Agency's GAIA observatory. GAIA was designed to observe distant stars with greater precision than …
To date, maybe, but that is just an estimate.
And I still can't find the definitive amount of stars in our Milky Way. Even on scientific channels on YouTube, quotes are in the 100 to 400 billion range, which is quite a range IMO.
On top of that, they only pulled an estimate after sampling less than 300,000 stars. I know you only need to poll 2000 people to get a statistically significant result, but still, 300,000 out of 100 to 400,000,000,000 seems a bit light to take that as an accurate figure.
But okay, it's the best we have for now. I can accept that.
You don't need to know the number of stars to know how much mass there is. It's easy to imagine calculating the average mass of a sample of stars, then multiplying by the number of stars overall but that's not how it's done.
The motion of stars as they orbit the galaxy is measured and from that you can estimate the galaxy's mass. The more stars' motions you look at, the better the result will be. It's just like working out the earth's mass from measuring the orbital parameters of a satellite, it bypasses the need to count all the earth's particles and sum their masses.
This is the method that led to the notion of "dark matter" in the first place. Measuring the mass of galaxies via stellar orbits and comparing to the mass derived from measuring the energy output of the same galaxies showed a big difference. It suggested that a lot of a typical galaxy's mass is not in shining stars, hence "dark".
Personally I still think that they have all made big "oops" somewhere in all these mass and distance calculations and that "dark" mass and energy stuff is just a fudge to make the flawed maths work.
One day someone will find the error and poof !! dark mass/energy vanish, probably a Nobel prize awaits those who find it.
To me when they say that "x" galaxy is 13 billion light years away and this just after the "big bang", that's where it was that time ago, it certainly is not there now and everything has been moving for that time. Yeah I know all about space/time fabric and all that stuff they go on about in "how the universe works" documentaries but I feel there is a fundamental flaw in these distance measurements.