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Japan Space

Volunteers Use Annular Eclipse To Measure Sun More Accurately 75

Posted by timothy
from the maybe-it's-just-been-eating-differently dept.
Anonymous Squonk writes "The measurement of the sun currently in use was actually calculated over 120 years ago, and is off by hundreds of kilometers. Thousands of ordinary Japanese citizens worked together to improve this estimate. By measuring the borders of the 'ring of fire' effect of the recent eclipse, and using the known size and distance from the Earth of the sun, the radius of the Sun was measured as 696,010 kilometers, with a margin of error of only 20 kilometers."
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Volunteers Use Annular Eclipse To Measure Sun More Accurately

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  • Incidentally... (Score:5, Interesting)

    by fuzzyfuzzyfungus (1223518) on Friday May 25, 2012 @03:04AM (#40107057) Journal
    I very strongly doubt that this is relevant on the scale of recorded human history and naked-eye observation; but doing all that mass-energy conversion and indiscriminate radiating must be slowly changing the sun's size, with some sort of balance between loss of mass and thermal expansion or contraction.

    I'm told that the 'expands and engulfs the inner planets' stage will be dramatic; but is the expectation before that event a very, very gradual shrinking or something more complex?
    • by Anonymous Coward

      Well, I would assume a gradual expansion.

      Since the more reactions happen, the more mass it loses, thus the attraction on the nearby atoms/molecules lessen, thus allowing them to go a bit further away.

    • Re:Incidentally... (Score:5, Informative)

      by Anonymous Coward on Friday May 25, 2012 @04:32AM (#40107359)

      The Sun is growing right now and it is getting brighter by the day. This is not occurring at a rapid rate at the present time. It is due to the slow accumulation of helium in the core of the Sun. Helium doesn't undergo fusion at this time (not hot enough). The increase in helium would imply a decrease in the fusion rate, but due to maintaining a hydrostatic equilibrium, the temperature of the core increases and the fusion rate actually increases. This causes the radius to increase.

      • Obviously the sun is getting hotter. Haven't you heard of global warming? If we don't do something soon, we'll get completely enveloped by the sun.

    • by dwye (1127395)

      but doing all that mass-energy conversion and indiscriminate radiating must be slowly changing the sun's size

      This assumes that the Sun actually *has* a size, in a real, rather than purely mathematical sense. The outer layers of the Sun are a translucent vacuum. A harder vacuum than we were able to achieve for most of the 20th C, glowing like a neon light so that the visibility through those outer layers is about what the old London Pea Soup fogs were like. If we could view it in infrared, the Sun would have a larger "diameter" than this measurement, and of course smaller if measured from its ultraviolet image,

  • by Scarletdown (886459) on Friday May 25, 2012 @03:15AM (#40107093) Journal

    I think to get the most accurate measurement, we need to send a manned mission to the sun and do it the old fashioned way, with a tape measure.

    Of course, to keep from burning up, they will have to go at night.

  • ...if TFA were in the same language as the TFS?
  • by jtownatpunk.net (245670) on Friday May 25, 2012 @03:31AM (#40107147)

    That's a relatively open weave and I can still see your... annular area.

  • by zmooc (33175) <zmooc&zmooc,net> on Friday May 25, 2012 @03:43AM (#40107201) Homepage

    Good to see they focused their research on the sun that's currently in use and not on one of those old disposed ones!

  • by Anonymous Coward on Friday May 25, 2012 @03:56AM (#40107233)

    NASA seemed to know it's 696,000km long before this experiment [nasa.gov].

  • I missed it (Score:4, Funny)

    by The Evil Atheist (2484676) on Friday May 25, 2012 @04:09AM (#40107277) Homepage
    Oh well, look on the bright side...
  • Oh my god (Score:5, Funny)

    by Anonymous Coward on Friday May 25, 2012 @04:14AM (#40107299)

    The measurement of the sun currently in use was actually calculated over 120 years ago, and is off by hundreds of kilometers.

    By the best available measurements the sun has shrunk by hundreds of kilometers in a space of 120 years... and in that time is when we've started using solar power. We should stop now while there's still some Sun left.

  • Define 'Sun' (Score:4, Interesting)

    by EasyTarget (43516) on Friday May 25, 2012 @05:20AM (#40107451) Journal

    Seriously; it has a atmosphere thousands of miles thick, with a fuzzy, boiling edge..

    The margin of error on this is ludicrous.

    Plus.. of course, it is continually boiling itself off onto space, so even if you could define a 'hard edge' to it, your measurements would become worthless in, say, a few million years ;-)

    • by Hentes (2461350)

      This, it's a cloud of gas and defining its surface based on a given brightness (I guess, since this is an optical measurement) is pretty arbitrary.

  • by Alain Williams (2972) <addw@phcomp.co.uk> on Friday May 25, 2012 @05:47AM (#40107517) Homepage

    Is this not somewhat akin to trying to measure the depth of a saucepan of boiling water ?

    • by MalachiK (1944624)
      Yeah, but I'd guess it's pretty smooth when you consider the radius of the sun is of the order 10^9 m.
  • ... strange cases of sudden blindness have been sweeping across Japan, affecting thousands of citizens. Said one man, "I saw a blinding ring of light and then nothing! It was as though I had seen the nuclear breath of Gojira!"
  • Can we get it translated from the original Japanese to English by a person who speaks both languages fluently?
    • Can we get it translated from the original Japanese to English by a person who speaks both languages fluently?

      Well, I don't have time to do the whole thing, but here's the gist: </moz-synch-lips> "Oh no Sun-Zilla!"

  • by n7ytd (230708) on Friday May 25, 2012 @10:25AM (#40108857)

    Japanese citizens worked together to improve this estimate. By measuring the borders of the 'ring of fire' effect of the recent eclipse, and using the known size and distance from the Earth of the sun, the radius of the Sun was measured as 696,010 kilometers, with a margin of error of only 20 kilometers."

    Wow! That's some breakthrough science!

  • I live in Western Canada, and we were supposed to get as much as 80% coverage of the sun at my location, near sunset. I even managed to secure some solar glasses especially for watching the event. It had been sunny for almost two whole weeks before the event, with barely a cloud in the sky. The eclipse happens and BAM... it's so freakin' overcast and rainy that you can't even tell which way the sun *IS*.

    Before sunset the next day, the clouds had cleared, and it's been sunny ever since.

    The universe h

  • Since I can't read the full article (due to both registration and source language), can someone who does read Japanese, go through the article and check to see how through they were about correcting for atmospheric refraction, using proper ephemeris data for the base distance, etc? Somehow, I think SOHO, STEREO, and professional ground-based solar observatories have a better handle on this.
  • Surely this is no news at all; the Sun has been measured as accurately as possible (given that it doesn't have a well-defined edge) by satellite telemetry long ago. This should perhaps be titled 'most accurate calculation by amateur Japanese without modern equipment' or something

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