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Space Science

Orion Nebula Gets New Milepost Marker, Now Closer 93

Posted by CowboyNeal
from the objects-in-mirror-may-be-closer-than-they-appear dept.
twilight30 writes "Discovery News is reporting that 'One of the most famous and scrutinized heavenly objects is 10 to 20 percent closer than we thought, say two teams of radio astronomers who have made some of the most precise cosmic distance measurements ever, with a telescope nearly as big as Earth. The Orion Nebula is the closest major stellar nursery to Earth, so it has been heavily studied to learn about the lives of stars. Its distance from Earth, however, has long been a matter of uncertainty, with an estimate made about 25 years ago in need of revision.'"
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Orion Nebula Gets New Milepost Marker, Now Closer

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  • by Anonymous Coward on Thursday October 11, 2007 @09:13PM (#20948407)
    That's nothing. They needed a computer nearly the size of Jupiter to process the data.
    • by opus (543) * on Thursday October 11, 2007 @09:17PM (#20948447)
      The VLBA was aimed at one of the few radio-wave emitting stars in Orion, which was viewed twice in a single a year. The almost 200-million-mile width of Earth's orbit around the sun allowed the VLBA to serve as one eye, then again as the other eye six months later.

      Wouldn't that be a telescope 200-million-miles wide, using the same poetic license that led them to say they used a telescope as big as the earth.

      • Re: (Score:1, Insightful)

        by Anonymous Coward
        Saying that the telescope was "nearly as big as Earth" is dead wrong. The effective aperture of the telescope, for this purpose, is twice the radius of the orbit of Earth around the sun, or almost 200 million miles. Gotta love those science reporters...
        • by glavenoid (636808) on Friday October 12, 2007 @12:47AM (#20949773) Journal
          Wrong again. The 2 points, ~200 million miles apart were used as points in a measure of parallax. The virtual aperture of the VLBA scope is ~5000 miles diameter, which isn't *quite* "nearly as big as earth". Still a pretty big aperture, even though it's not a complete circular area, the resolution provided is apparently sufficient to measure the stellar (nebular?) parallax wrt M42.

          What I find more interesting in this article is the close relationship alluded to between the trapezium and the nebula...

      • Re: (Score:3, Interesting)

        by SnoopJeDi (859765)
        Not to mention if you consider that the awful comparison seems to suggest Gravitational Lensing [wikipedia.org].
    • Re: (Score:2, Funny)

      by mstahl (701501)

      Maybe we'll get a better answer than "42" this time then!

    • "Impacted" Plot: In the year 2050 the Earth almost crashes into the Orion Nebula, only to be rescued from destruction by two nerdy radio astronomers from Parkes Observatory in the middle of nowhere in Australia, who, whilst trying to find a cure for constipation from eating too much McDongles(TM) Impact McBurglettes, find that by injecting massive amounts of First Fleet Enema into the Nebula they can cut a path through the Nebula. The romantic part of the movie is where the local district nurse shows up an
    • by Nimey (114278)
      How many Ping-Pong balls & how many Libraries of Congress, please.
      • by nschubach (922175)
        Pfft.. they measure things here in America on Football fields, Empire State Buildings and Statues of Liberty.
  • by syrinje (781614) on Thursday October 11, 2007 @09:18PM (#20948457)
    I wonder what they mounted it on! And yes, I did not RTFA - this is /., you insensitive clod
  • Aren't they measuring the distance to stars within a three-dimensional object? I would guess that they could pick two stars that appear close together along our line of sight and come up with wildly different distances. Now perhaps if they measured the distance to one of the Trapezium stars (a very bright formation thought to lie at the "heart" of the nebula) they could come up with some meaningful measurement of distance. Just thought of something else. Let's find a really large repository for data and cr
    • Re: (Score:3, Informative)

      Aren't they measuring the distance to stars within a three-dimensional object? I would guess that they could pick two stars that appear close together along our line of sight and come up with wildly different distances. Now perhaps if they measured the distance to one of the Trapezium stars (a very bright formation thought to lie at the "heart" of the nebula) they could come up with some meaningful measurement of distance. Just thought of something else. Let's find a really large repository for data and create a three-dimensional map of the nebula. Don't try to shove this single star data down my throat!

      It is true that the nebula is three dimensional, but it is nowhere near 1/10th the distance from earth to the orion nebula. The margin of error associated with the "front" of the nebula with the "back" or "center" of the nebula is a fraction of a fraction of a percent. (and I purposely used relative terms to demonstrate where error can lie)

      Additionally, they did not use line of sight. They were using radio telescopes making them able to "see" the star at the center of the nebula without necessarily havin

      • by nschubach (922175)
        But if you have two points of Earth in it's rotation and one point of star you should be able to triangulate the distance. So tracking one star should be enough to give you a guess. I assume they picked multiple stars to get an average for all bodies in question. I actually would have been interested to run the photos (or radio information as is the case) and the progression information from about every month for the six month rotation through a program to compare stars movement and form an average on mo
  • summary (Score:2, Funny)

    by evwah (954864)
    how the summary should have gone: /summary
    the orion nebula is ___ light years away /end summary

    end of story :P
  • by CODiNE (27417) on Thursday October 11, 2007 @09:48PM (#20948705) Homepage
    Let's just wait a little longer and we won't have to reprint all those textbooks.
  • by LordP (96602) on Thursday October 11, 2007 @10:04PM (#20948803) Homepage
    Measured incorrectly, or has the Orion Nebula just been sneaking closing over the last 25 years?
    • by jamesh (87723) on Thursday October 11, 2007 @10:33PM (#20949009)
      Hmmm... 10 to 20 percent closer in 25 years... (gets out calculator)... that means that it will be here in 125 to 250 years!!!

      I for one welcome our invading Orion Nebula overlords.
    • Bower and his colleagues came up with a distance of 1,270 light-years, give or take 76 light-years. That compares with the previous estimate of 1,565 light-years, give or take 266.

      There's still overlap in the uncertainties of the measurements. So it wasn't incorrectly measured, just measured with a 17% error margin. The only ones who are incorrect are the people who quote the estimate without including the uncertainty.

    • At best it should be only funny.

      Orion nebula distance : 1500 light years. 10% of this : 150 light years. IF you suppose that it is getting closer by that distance, then it means roughly 5+ light years for every years for 25 years. Nothing goes at a speed of 5+ light years per year. At best all physical stuff can only goes at near c (1 light year per year ;)...) with photon going at exactly c in vacuum. And we would remark the relativistic effect, at those speed with such an enormous mass... (is that even
    • by Mushdot (943219)

      Maybe it's like that scene in The Holy Grail, where the Knight is running toward the castle and not getting any closer.

      Then all of a sudden, 'ahaaaa!' he appears at the gate and stabs the guards.

  • by autophile (640621) on Thursday October 11, 2007 @10:05PM (#20948811)

    Warning: Objects in telescope are closer than they appear.

    --Rob

  • Translation (Score:5, Funny)

    by Anonymous Coward on Thursday October 11, 2007 @10:16PM (#20948883)
    >One of the most famous and scrutinized heavenly objects is 10 to 20 percent closer than we thought

    In other words, Natalie Portman moved from Boston to New York.
  • It *was* nearly the size of Earth after all!
  • Isn't the galaxy *lens*-shaped ... ;)
    Humour Disclaimer - yes, no medium change, therefore a refractive index ratio of 1 ... unless you count stars as being "like atoms" in that they are *relatively* small "solid" object with large spaces in between them, suspended in a "space". Then therefore we *do* have a medium change and a ratio of refractive indices: light passes from an area of space populated by N stars / lightyear^3 to an area of space with M stars / lightyear^3 where N << M, and the N popula
  • Oh My GOD! (Score:4, Funny)

    by grumling (94709) on Friday October 12, 2007 @01:08AM (#20949849) Homepage
    It's coming right at us!

    Looks like I picked the wrong week to stop sniffing glue...

    -Steve McCroskey
  • The Galactica is closer to Earth than we thought!
  • by SirBruce (679714) on Friday October 12, 2007 @03:52AM (#20950463) Homepage
    The old measurement was 1,565 +/- 266 LY.

    Bower's new measurement is 1,270 +/- 76 LY.

    Assuming both error bars are correct, then by combining the two measurements we get between 1,299 LY and 1,346 LY.

    Reid's new measurement is 1,350 +/- 23 LY.

    So combining again, we can conclude the Orion Nebula is between 1,327 and 1,346 LY away, or 1,336.5 LY +/- 9.5 LY.
    • You can't combine statistics like that.

      We have no idea of the accuracy of either measurement (specifically because we don't actually know how far away it is).

      What we do know is that the new measurement is more precise. It's probably also safe to assume that the new one's at least slightly more accurate.

      The troubling bit is that the median of the new measurement is considerably lower than the original, and lies outside of the error bars of the original estimate. This suggests that there's a good chance tha
    • That's not how you combine numbers with error bars. First, you do weighted average based on how small the error bars are: 1/(1/266+1/76+1/23) * (1565/266 + 1270/76 + 1350/23) = 1346 LY And then to find the error, you take the square root of the sum of the squares of all the errors in the final number that are introduced by the errors in the initial numbers: sqrt(1/(1/266+1/76+1/23) * ( (266/266)^2 + (76/76)^2 + (23/23)^2 ) = +- 7 light years.
    • by cdpage (1172729)
      Based on the Potential Old Measurement and Bowers measurement, 1565 + 266 = 1299 1270 + 76 = 1346 Rieds new new is 1350 +/- 23 seems like they were not far off in the first place.
      • Based on the Potential Old Measurement and Bowers measurement, 1565 + 266 = 1299
        Are you a programmer for Excel 2007?
    • "So combining again, we can conclude the Orion Nebula is between 1,327 and 1,346 LY away, or 1,336.5 LY +/- 9.5 LY."

      Since your numbers are not scientific, you should just round to 1337 LY. :P

      strike
  • NED: Oh, no it's coming right for us. Jimbo: Quick Ned, the rocket launcher.

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