Milky Way Heavier Than Thought, and Spinning Faster 285
An anonymous reader writes "The Milky Way is spinning much faster and has 50 per cent more mass than previously believed. This means the Milky Way is equivalent in size to our neighbor Andromeda — instead of being the little sister in the local galaxy group, as had been believed. One implication of this new finding is that we may collide with Andromeda sooner than we had thought, in 2 or 3 billion years instead of 5."
Showing My Ignorance (Score:2, Insightful)
But how do you calculate the rate of rotation and mass of a galaxy that you're in? It's mind blowing that we can actually do that.
I haven't read the paper, but... (Score:2, Insightful)
I think the article oversimplifies. The Milky Way doesn't rotate as one single piece. It's made up of billions of stars (duh!) which revolve around the center at different velocities. So, the question is, is the quoted speed the speed at which the Sun revolves around the galactic center or the average speed of the arms (which move much slower than the stars)? Maybe more later if I can find the paper on arxiv.org
Re:Reassuring (Score:4, Insightful)
No can do.
However, we may be able to dupe this tomorrow and then again a few years from now when its on Digg.
Thanks for your understanding,
The Management
Re:From TFA (Score:4, Insightful)
"...the galaxy is rotating at a speed of 965,600 km/h, compared to previous estimates of 804,672 km/h, the astronomers report."
Anyone else think it odd that the previous estimate had six significant digits, yet was apparently off by ~20%?
Re:hello... (Score:3, Insightful)
Of course they are. But "more mass" implies "heavier" just as much as "more weight" does!
rj
Re:From TFA (Score:4, Insightful)
The odd thing is not the estimate (500,000 mph has one significant digit) but its conversion to km/h.
Re:Showing My Ignorance (Score:3, Insightful)
I'm no physicist, but I do know that the orbital velocity of an object depends on two things: its distance from the system's center of gravity and the mass of the system in question. Getting a more accurate measure of our orbital velocity gave us a better estimate of the mass.
They keep swapping the title (Score:3, Insightful)
It seems like whether the Milky Way or Andromeda is bigger changes every couple years, as this paper or that paper claims a measurement showing one or the other is actually a lot bigger than we all thought.
We used to think the Milky Way was bigger (and before that, thought Andromeda was bigger for the longest time), and then recently we got some evidence that Andromeda was actually bigger after all. And then there's this piece about the Milky Way actually be bigger after all.
Me? I'm going to sit back and let the scientists figure it out for a few more decades before deciding. All we really know is that Andromeda and the Milky Way are by far the two biggest galaxies in our Local Group, and they're probably close enough in size to make figuring out which one is really bigger a bit tricky.
You should PLAN on being dead. Just don't die. (Score:3, Insightful)
If you don't plan on what happens after that, someone else will (no pun intended).
Planning on something isn't the same as wishing for it.
As for me, WRT "the singularity"? If I could upload "myself", would I? I don't know. Probably. But if you think about it, "you" don't get to go, only your "branch/copy" does. Are you that selfless? What if it costs money? Are you willing to pay for "his" immortality? AFAIK, the first sentence stands alone.
Re:From TFA (Score:3, Insightful)
Precision != Accuracy.
The previous measurement had 6 significant digits of precision.
They just happened to be inaccurate.
Note that the new estimate seems to have *less* precision (assuming that only the first 4 digits are significant), but is claimed, at least, to have more accuracy.
Re:Science (Score:3, Insightful)
I've read that a bigger risk is that of a nearby super-nova. The collision will likely trigger extreme star formation due to the stirring up of interstellar gas. Thus, it will be quite a fire-works show for a while.
Re:Science (Score:1, Insightful)
Doesn't need to be a local collision to be deadly.
In colliding galaxies, a great deal of energy in the form of x-rays/gamma rays is emitted, making the whole neighborhood a dangerous place.
Re:Declaration of inter-galactic hostilities (Score:3, Insightful)
Ninjdromeda's gonna kick our ass...physics be damned!
Dude, we can see them coming 2-3 billion years in advance. I don't think they're ninjas.