Slashdot Mirror

← Back to Stories (view on slashdot.org)

Volunteers Use Annular Eclipse To Measure Sun More Accurately

Posted by timothy on 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."

13 of 75 comments (clear)

  1. Incidentally... by fuzzyfuzzyfungus · · Score: 4, Interesting

    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?

    1. Re:Incidentally... by SuricouRaven · · Score: 4, Interesting

      Don't forget the cycle too. Sunspots go up, sunspots go down.. that means a change in temperature, and as basically a ball of gas a change in temperature means a change in volume. I don't know how significent this pulsing effect would be, but if you can do measurements to 20km it might be measurable.

    2. Re:Incidentally... by Anonymous Coward · · Score: 5, Informative

      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.

    3. Re:Incidentally... by thoughtsatthemoment · · Score: 5, Informative

      To be more precise, the sun will become a red giant in about 5 billions, engulf the earth, and eventually fade as a white dwarf, whose volume is about the same as the earth.

    4. Re:Incidentally... by Hognoxious · · Score: 5, Funny

      You had me in a panic there - I thought you said millions.

      --
      Confucius say, "Find worm in apple - bad. Find half a worm - worse."
  2. Manned Mission Needed by Scarletdown · · Score: 5, Funny

    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.

    --
    This space unintentionally left blank.
    1. Re:Manned Mission Needed by Grayhand · · Score: 4, Funny

      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.

      A waste of time and money. The eclipse proved that the sun is only slightly larger than the moon. Now you just have to use a tape measure to get an accurate size for the moon. Too bad the astronauts didn't think to take one.

    2. Re:Manned Mission Needed by qu33ksilver · · Score: 4, Funny

      Or during Winter.. You know this was a yahoo question. http://answers.yahoo.com/question/index?qid=20120430182228AAIk7uw

    3. Re:Manned Mission Needed by __aaltlg1547 · · Score: 4, Funny

      Everybody knows a Corona is 12 ounces.

  3. Re:Wouldn't it be great... by Black+Parrot · · Score: 4, Funny

    Wouldn't it be great if people learned foreign languages ? If people would allow foreigners to puplish in their on language ?...
    Yeah too much to ask, I guess.

    IMO everyone should be allowed to puplish in the language of their choice, so long as they do it in the privacy of their own home.

    --
    Sheesh, evil *and* a jerk. -- Jade
  4. I missed it by The+Evil+Atheist · · Score: 4, Funny

    Oh well, look on the bright side...

    --
    Those who do not learn from commit history are doomed to regress it.
  5. Oh my god by Anonymous Coward · · Score: 5, Funny

    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.

  6. How accurate can it be ? by Alain+Williams · · Score: 4, Insightful

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