Stories
Slash Boxes
Comments
Search

News for nerds, stuff that matters

Slashdot Log In

Log In

Create Account  |  Retrieve Password

Milky Way Heavier Than Thought, and Spinning Faster

Posted by kdawson on Mon Jan 05, 2009 09:50 PM
from the bulking-up dept.
Space Science
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."
+ -
story

Related Stories

Submission: Milky Way faster and heavier than thought by Anonymous Coward
[+] New Paper Offers Additional Reasoning for Fermi's Paradox 774 comments
KentuckyFC writes "If the universe is teeming with advanced civilizations capable of communicating over interstellar distances, then surely we ought to have seen them by now. That's the gist of a paradoxical line of reasoning put forward by the physicist Enrico Fermi in 1950. The so-called Fermi Paradox has haunted SETI researchers ever since. Not least because if the number of intelligent civilizations capable of communication in our galaxy is greater than 1, then we should eventually hear from them. Now one astrophysicist says this thinking fails to take into account the limit to how far a signal from ET can travel before it becomes too faint to hear. Factor that in and everything changes. Assuming the average communicating civilization has a lifetime of 1,000 years, ten times longer than Earth has been broadcasting, and has a signal horizon of 1,000 light-years, you need a minimum of over 300 communicating civilizations in the Milky Way to ensure that you'll see one of them. Any less than that and the chances are that they'll live out their days entirely ignorant of each other's existence. Paradox solved, right?"
This discussion has been archived. No new comments can be posted.
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.

Milky Way Heavier Than Thought, and Spinning Faster 50 Comments More /

 Full
 Abbreviated
 Hidden
More
Loading... please wait.

  • The good news (Score:5, Funny)

    by Anonymous Coward on Monday January 05 2009, @09:51PM (#26338639)

    At least now we don't have to worry about our sun going nova, we'll all die in an intergalactic traffic accident first.

  • I'll be counting the days (Score:5, Funny)

    by Kohath (38547) on Monday January 05 2009, @09:54PM (#26338673)

    ..on my Zune

      • Re: (Score:3, Funny)

        by Kohath (38547)

        Timeline revisions of 2-3 Billion years are now to be expected. A patch will be made available before this becomes an issue in the year 2012000000.

  • hello... (Score:2, Informative)

    by Anonymous Coward

    Mass != weight

    • Mass may not equal weight, numerically, but the more mass, the more weight. So the idea is still relevent

      • Re: (Score:3, Funny)

        by fm6 (162816)

        That's some heavy thinking. You must have a massive intellect.

        • Re: (Score:3, Insightful)

          by Deadstick (535032)

          Of course they are. But "more mass" implies "heavier" just as much as "more weight" does!

          rj

          • Re: (Score:3, Informative)

            by mpeskett (1221084)

            A massive object in near-zero gravity weighs less than a smaller object in very strong gravity... that's sort of what weight means.

            I agree it's pedantry to insist that the headline be perfectly accurate, but you're still wrong.

  • Reassuring (Score:3, Funny)

    by Anonymous Coward on Monday January 05 2009, @09:57PM (#26338697)

    For a while there I was worried it had dropped down to 1 billion years.

  • Science (Score:5, Interesting)

    by maz2331 (1104901) on Monday January 05 2009, @09:59PM (#26338715)

    One thing that is great about science is that it does have a way of eventually finding errors and correcting them in the face of new evidence.

    As far as galactic collisions are concerned, we are in no immediate danger. 2-3 Gy vs 5 is an academic exercise, as the Sun will most likely increase its output sufficiently by then to boil off the Earth's oceans anyway,

    Besides, the density of a galaxy (outside of the core) is so low that the chance of a stellar or planetary collision is negligable anyway.

    Or, by then, we would have the technology to detect it and either deflect it or GTFO of the way anyhow.

    Still, it is nice to know we're not in the pipsqueak galaxy. Hoorah!?!?

    • Re:Science (Score:5, Funny)

      by Dutch Gun (899105) on Monday January 05 2009, @10:08PM (#26338781)

      Still, it is nice to know we're not in the pipsqueak galaxy. Hoorah!?!?

      The Miiilky Waaay... Fuck, yeah!

    • Re: (Score:3, Insightful)

      by Tablizer (95088)

      Besides, the density of a galaxy (outside of the core) is so low that the chance of a stellar or planetary collision is negligable anyway.

      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: (Score:3, Informative)

      by MBGMorden (803437)

      Still, it is nice to know we're not in the pipsqueak galaxy. Hoorah!?!?

      Well, we never really were. The Local Group contains a few dozen galaxies, of which the Milky Way was already known to be one of the "big 3" (Andromeda, The Milky Way, and The Triangulum galaxies all being pretty big in comparison to most of the others in the group). It's just that now instead of being #2 we might just be #1 :).

  • Well, that'll show those Andromedans not to attack "smaller" galaxies. Now who's laughing! We will plunder their mass (while watching colateral ejected mass fly out).

  • oh well.. still leaves plenty of time to debate which is the most robust backup method after all then?

  • I for one... (Score:4, Funny)

    by alexborges (313924) on Monday January 05 2009, @10:01PM (#26338739)

    Thought I was drunk.

    Good to know it was the milky way spinning all too fast.

  • The Earth's Solar System is located some 28,000 light years from the centre of the Milky Way. At that distance, the new measurements show that the galaxy is rotating at a speed of 965,600 km/h, compared to previous estimates of 804,672 km/h, the astronomers report.

    965,600 km/h = 268 222.222 m/s or about 1/1117th of the speed of light...

    • Re:From TFA (Score:4, Insightful)

      by thomasferraro (1445925) on Monday January 05 2009, @10:37PM (#26338969) Homepage

      "...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:From TFA (Score:4, Funny)

        by Quinapalus (1335067) on Monday January 05 2009, @10:42PM (#26339015)
        I think my chemistry teacher would have taken off points for that one.

      • Re:From TFA (Score:4, Insightful)

        by Anonymous Coward on Monday January 05 2009, @10:58PM (#26339105)

        The odd thing is not the estimate (500,000 mph has one significant digit) but its conversion to km/h.

      • Re: (Score:3, Insightful)

        by caerwyn (38056)

        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.

  • 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.

    • Depends, how much time do you have to make observations? It's probably rather easy if you got a couple million years to burn.

    • 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.

      Simple, the girl astronomers don't mind asking neighboring galaxies for directions. (Stubborn guys try to use math and stuff.)
           

      • As for mass, I would guess it has something to do with using spectrometers to get good ideas about out how much of each element is out there

        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.

  • Way Heavier Than Thought, and Spinning Faster (Score:5, Funny)

    by bobdotorg (598873) on Monday January 05 2009, @10:11PM (#26338813)

    Ugh. Sounds like scientists just discovered my last blind date.

  • Ahah! (Score:5, Funny)

    by sleeponthemic (1253494) on Monday January 05 2009, @11:02PM (#26339121) Homepage
    Twice as heavy! Talk about getting it wrong.

    It's only a matter of time before the earth's age is readjusted to 6000 years!

  • They keep swapping the title (Score:3, Insightful)

    by GleeBot (1301227) on Tuesday January 06 2009, @12:05AM (#26339503)

    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.

  • we age slower then (Score:3, Funny)

    by at_slashdot (674436) on Tuesday January 06 2009, @04:03AM (#26340493)

    Does that mean that we age slower compared to the people in Andromeda?

    • Re:I haven't read the paper, but... (Score:5, Interesting)

      by boot_img (610085) on Monday January 05 2009, @10:21PM (#26338887)

      Actually the orbital velocity is (surprisingly) close to constant, as in most spiral galaxies. In fact, it is these "flat" (i.e. constant as a function of galactocentric radius) rotation curves that were some of the earliest evidence for dark matter.

      That having been said, my guess is that the velocities quoted in the press release refer to the Sun's (or more accurately the Local Standard of Rest's) velocity around the Galactic center.

      Couldn't find the paper on arxiv.org ...

       

      • Re:From TFA: (Score:5, Interesting)

        by aXis100 (690904) on Tuesday January 06 2009, @12:04AM (#26339495)

        The visble arms of our galaxy's spiral aren't a fixed buch of stars clustered togther, it's a density wave that travels around the disk. Our solar system will pass in and out of various arms (eventually) as the density wave is travelling at a different speed to the actual rotation.

All trademarks and copyrights on this page are owned by their respective owners. Comments are owned by the Poster. The Rest © 1997-2009 Geeknet, Inc.