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Space Science

Milky Way Heavier Than Thought, and Spinning Faster 285

Posted by kdawson
from the bulking-up dept.
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."
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Milky Way Heavier Than Thought, and Spinning Faster

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  • 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.

    • by conureman (748753)

      A far more stimulating demise, IMHO.

    • by NotQuiteReal (608241) on Monday January 05, 2009 @09:56PM (#26338689) Journal
      At least now we don't have to worry about our sun going nova, we'll all die in an intergalactic traffic accident first. Probably not. Even when galaxies collide, the odds of something hitting the solar system are remote.

      But the night sky will look even prettier for the future cockroach decedents, if they have evolved enough to "look up" by then.

      Personally, I plan on being dead in a time span that measures in decades, not billions of years.
      • Re:The good news (Score:5, Informative)

        by Deadstick (535032) on Monday January 05, 2009 @10:23PM (#26338901)

        the future cockroach decedents

        They'll be the descendants. We'll be the decedents.

        rj

      • Why plan on being dead at all? We may yet live to see the singularity...

        • by click2005 (921437) on Monday January 05, 2009 @11:31PM (#26339279)

          I was hoping to win a Darwin Award in a few billion years for 'collided with another galaxy'

        • Statistically speaking, you will die.

          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.
      • by shiftless (410350)

        Personally, I plan on being dead in a time span that measures in decades, not billions of years.

        Speak for yourself--I plan to live forever.

    • Re: (Score:3, Informative)

      by Anonymous Coward

      I know you're trying to be funny but when the two galaxies do meet, the odds are no stars will collide.

    • by MrNaz (730548) * on Monday January 05, 2009 @10:21PM (#26338885) Homepage

      I hope we're insured. Imagine if the other guy sues!

    • by aliquis (678370)

      Except collapsing galaxies probably isn't as bad as it sound.

    • by wtansill (576643)

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

      Better start getting quotes from Geico on upgraded insurance then...

    • by Kingrames (858416)
      No, we'll be fine. We've installed intergalactic airbags. They're called politicians.
    • Re: (Score:3, Informative)

      by Dasher42 (514179)

      Actually, at the rate our sun is heating up [bbc.co.uk] as a natural part of its life cycle, we've got about 500 million years to get off this rock. So, we don't get to see that firey end anyway.

    • Good thing, because our local star (aka the Sun) doesn't have enough mass to go nova. It'll be a Red Giant swelling to absorb the atmospheres of the inner planets. It will then eventually shrink back down to a white dwarf and eventually die a completely lonely death. Unless we get lucky and we slam into one of those Andromedan supergiants.

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

    ..on my Zune

  • hello... (Score:2, Informative)

    by Anonymous Coward

    Mass != weight

    • by Deadstick (535032)

      OK, so you want to maintain scientoideological purity and claim "heavy" only has to do with gravity...so what? Two kilograms is still heavier than one kilogram, no matter what gravity you apply to them.

      rj

      • Re: (Score:2, Informative)

        by MrNaz (730548) *

        No, he's pointing out the pretty basic fact that mass and weight are measures of two different things.

        • Re: (Score:3, Insightful)

          by Deadstick (535032)

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

          rj

          • by Nutria (679911)

            just as much as "more weight" does

            No. It implies that you're near a much larger mass. Astronaut on Moon vs astronaut on Earth.

          • 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.

      • Re: (Score:3, Funny)

        by fm6 (162816)

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

    • Re: (Score:3, Informative)

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

    • 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:2, Funny)

      by Anonymous Coward

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

      Let's go to the Magellanic Clouds and look for somebody to beat up!

    • "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,"

      True. I've heard estimates that predict in about 900 million years, the oceans will have boiled due to the increased energy output from the sun. Between that, and whatever else we could do to doom ourselves, it kind of wants to make you get into space as quickly as possible, no?
    • by Nutria (679911)

      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.

      It's also what makes many educated lay people suspicious when scientists categorically assert that Global Warming Is Upon Us, and We're All Going To Die, so quick, lets over-regulate every facet of everyone's lives, because We Went To University, So We Know What's Good For You.

      I love the Scientific Method, and I think it's the only way to discover Reality, but we have

    • 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 :).

  • by dfsmith (960400) on Monday January 05, 2009 @09:59PM (#26338721) Homepage Journal
    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).
  • by somewhere in AU (628338) <alexm@findmap.com.au> on Monday January 05, 2009 @10:00PM (#26338735) Homepage

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

  • 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.

      • "...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%?

        Anyone else think it odd that they measured angular velocity in linear units? WTF?

  • by notseamus (1295248)

    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.

    • by Rakishi (759894)

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

    • by McGiraf (196030)

      it seem they got it wrong at least once so far ...

    • by mhall119 (1035984)

      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.

      Science.
      It works, Bitches [xkcd.com].

    • Re: (Score:3, Funny)

      by Tablizer (95088)

      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.)
           

    • Speed: if you know a constellation of stars is in our galaxy, then you can track it's movement speed. Especially since we have software that'll give the position of constellations right back to egyptian times, etc.

      Mass: they're working this out based on the rotation speed.

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

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

  • 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

    • 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 ...

       

    • by Tablizer (95088)

      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.

      No wonder our neighbors keep shifting away. I thought it was because they were on to our wireless thievery.
         

  • ... should have used low fat milk...
  • Whoa, for a moment I thought you said _million_ years. No need to panic, people.

  • 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!
  • Does this mean they'll take the candy out of the vending machines since it's obviously leading to obesity on a galactic scale?
  • You know an astronomer has found an unusually accurate measuring technique when the error bars get as low as 50%. Now that best value for the mass of the Milky Way has 1-sigma error bars of 50%, I'm glad to be able to say with 95% statistical confidence that its mass is greater than zero. On the other hand, for the "glass is half empty" folks, there's still a 5% chance that its mass is negative.
  • Milky Way heavier than thought? Maybe it's your mom.

    Zing!

  • OK, so now that the galaxy is heavier/massive. Do we still need dark matter to explain how it works?
    • OK, so now that the galaxy is heavier/massive. Do we still need dark matter to explain how it works?

      More than ever. Dark matter was discovered (well, supposed) because of the way the galaxy rotates in an even fashion. Loose particles (ie, atoms of water in a cup) don't do that. Dense particles (ie, atoms of plastic in a CD) do. So there must be even _more_ dark matter than previously thought.

  • 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.

    • Re: (Score:2, Funny)

      by Tablizer (95088)

      It seems like whether the Milky Way or Andromeda is bigger changes every couple years, ... 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.

      When the tax collector comes by, we tinker with the books a bit, but then put it back big for advertising reasons.

  • Remember that the reason dark matter supposedly exist is because scientists calculated the weight of the visible matter in the entire universe and said "well that doesn't match up with the energy/gravity" so they make up some imaginary object to make up the difference. And then a couple years later OMG I guess we were 50% off of the mass of the milky way, oops. If they can't even measure our galaxy properly, then dark matter probably doesn't exist because they're just calculating it wrong. Either that or
    • You do realize that this discovery means that there is _more_ dark matter in the Milky Way, not less?

  • 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?

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