Volunteers Use Annular Eclipse To Measure Sun More Accurately

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Volunteers Use Annular Eclipse To Measure Sun More Accurately

Posted by timothy on Thursday May 24, 2012 @06:54PM 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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Incidentally... by fuzzyfuzzyfungus · 2012-05-24 19:04 · 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 Anonymous Coward · 2012-05-24 19:11 · Score: 2
  
  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.
2. Re:Incidentally... by SuricouRaven · 2012-05-24 19:13 · 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.
3. Re:Incidentally... by Anonymous Coward · 2012-05-24 19:45 · Score: 0
  
  Answer: Yes. The sun will continue to gradually shrink until it runs out of H to burn.
4. Re:Incidentally... by Anonymous Coward · 2012-05-24 20:32 · 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.
5. Re:Incidentally... by Grayhand · 2012-05-24 21:03 · Score: 2
  
  Answer: Yes. The sun will continue to gradually shrink until it runs out of H to burn.
  Actually the opposite is true. Our sun is doomed to end up a red giant and eventually the Earth will be eaten by the sun. It's a middle aged star so there are billions of years to go.
6. Re:Incidentally... by thoughtsatthemoment · 2012-05-24 21:38 · 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.
7. Re:Incidentally... by Hognoxious · 2012-05-24 23:37 · 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."
8. Re:Incidentally... by amnezick · 2012-05-25 00:20 · Score: 0
  
  let's agree to disagree a little. Earth orbits the Sun .. pretty fast to cover 360 degrees in 365 days. Sun dies .. it loses mass (lots of it) because it burns it and radiates it away. Less mass means less gravity. Why doesn't anybody take into consideration the centripetal force acting on Earth (and everything else that orbits around the Sun)? My guess is that as the Sun's gravity weakens the Earth will be allowed to further away from the Sun. I'm sorry but I don't see this engulf scenario happening at all. A more likely scenario: Sun is weak. Jupiter compresses a lot because it cools too much. Jupiter's mass is still enormous but now compared to it's size it allows other planets to come closer. It will not further that much away from the sun because big mass means big .. really big inertia. Earth however will be sort of slingshot eventually and it will either be catched by Jupiter (direct hit or very very very lucky but way too long shot catched in orbit as Jupiter's moon) or it will rocket towards empty space and maybe somewhere an advanced civilisation will discover our history. Enjoy your week-end and let the next millionth generation worry about the Sun engulfing the Earth ...
  
  --
  mov ax,4c00h
  int 21h
9. Re:Incidentally... by Anonymous Coward · 2012-05-25 00:37 · Score: 0
  
  By the time the Sun goes red giant it will still dwarf Jupiter by a mass factor of about 700.
10. Re:Incidentally... by Gaygirlie · 2012-05-25 01:04 · Score: 1
  
  Earth orbits the Sun .. pretty fast to cover 360 degrees in 365 days. Sun dies .. it loses mass (lots of it) because it burns it and radiates it away. Less mass means less gravity. Why doesn't anybody take into consideration the centripetal force acting on Earth (and everything else that orbits around the Sun)?
  My guess is that as the Sun's gravity weakens the Earth will be allowed to further away from the Sun.
  Earth's orbit will become more and more elliptical over time and will eventually either slingshot Earth out of the orbit and directly into the Sun.
  
  Earth however will be sort of slingshot eventually and it will either be catched by Jupiter (direct hit or very very very lucky but way too long shot catched in orbit as Jupiter's moon)
  I'm not a rocket-scientist or anything, but as far as I can see if Earth was getting slingshot out of orbit Jupiter would in no way have enough mass to catch it.
11. Re:Incidentally... by CrimsonAvenger · 2012-05-25 01:33 · Score: 1
  
  Earth's orbit will become more and more elliptical over time and will eventually either slingshot Earth out of the orbit and directly into the Sun.
  Earth's orbit will increase in radius (without becoming more elliptical) as the Sun's mass decreases, and when the Sun goes red giant, the Earth will vaporize.
  Unless, of course, we move the Earth before then.
  
  I'm not a rocket-scientist or anything, but as far as I can see if Earth was getting slingshot out of orbit Jupiter would in no way have enough mass to catch it.
  I agree, you're not a rocket scientist.
  Yes, it might be possible for Jupiter to catch Earth. EXCEPT that Jupiter's orbit will also be changing as Earth's orbit changes, and there's no special reason to believe that the two will ever come close enough together to interact meaningfully.
  
  --
  
  "I do not agree with what you say, but I will defend to the death your right to say it"
12. Re:Incidentally... by Anonymous Coward · 2012-05-25 01:35 · Score: 0
  
  E=mc^2 means that you can generate a lot of energy from very little mass. More than 99% of the mass of the Sun will remain when it goes into a red dwarf stage. But the increasing intensity of the Sun will destroy all life on Earth before then. Life on Earth has maybe 1 billion years left before the Sun wipes it out.
  You also talk about the gravity well that the Sun creates. If the Sun were to eject a lot of its mass (which it isn't going to do until it goes nova), then its gravitational potential would decrease and the Earth's orbit would expand. The same would occur to Jupiter. The central force (centripetal force) is proportional to the negative slope of the gravitational potential. The inertia of Jupiter means little unless the hypothetical mass ejection is abrupt. In that case Jupiter would go into an elliptical orbit.
  I'm sort of at a loss of why you mentioned Jupiter's compression. It is occuring (helium rain), but I don't see how that changes much. The Earth isn't going to approach Jupiter (5 AU). If Jupiter had such a major effect, it would have ejected the inner planets billions of years ago. Jupiter is significant primarily for the outer planets: the ejection of comets has pushed out the orbit of Neptune (and probably Uranus).
13. Re:Incidentally... by dwye · 2012-05-25 03:19 · Score: 2
  
  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, or its X-ray image for that matter.
  They have managed to get the exact size of a balloon in the process of being blown up and released. Not its maximum size or its minimum, but merely that of one random moment in the cycle.
14. Re:Incidentally... by progician · 2012-05-25 03:28 · Score: 1
  
  I never really considered this scenario, but there could be something in it. As a fixing note: the Sun is going to be a red giant first before it blows off the outer layers. The E=mc^2 means of course that only tiny fraction of the stars mass is transformed to energy due to the fusion. However, you have to still account for the mass that has been blown off by this energy. Most of this energy is turned to heat, light and radiation. While the heat/light accounts for no serious mass losses, I can easily imagine that the constant radiation over its roughly 10 billion year life time means quite a number of protons, electrons and neutrons leaving the Sun. Not to mention the coronal mass ejection where the solar wind is pushing out billions of tons of matter out of the Sun and hurtling toward the periphery of the Solar System. AFAIK, CME's can easily throw a magnitude of 10^12 kg of matter out. Over the period of 10 billion years, there are plenty of CME event. Just to stick to the wikipedia. An CME causing a loss in the average 1.6*10^12kg matter. The solar minimum rate of CME's is around once in 5 days, to the solar maximum's 3 times a day. I go with an arbitrary in-between value: 1 a day because it's easy to use :). (I don't have the time to go through the numerical integral of the solar cycles over its lifetime :)). 1 CME/day means around 3.65*10^12 eruptions over ten billion years, but let's go from our point of time (5.5 billion years remaining until the sun runs out of hydrogen): ~2.01*10^12 eruptions. This means in mass: 2*10^12 * 1.6*10^12 kg matter over the remaining days of the sun, 3.2*10^24kg. The Sun's mass is: 1.9891×10^30 kg So even if I calculate the overall mass loss of CME's, the sun would only lose: 1 / 621593.75 of her mass. To be honest, when I started to look up the facts and calculate, I thought I ended up with a new Nobel prize, but it seems nothing significantly will change in the orbit of Earth. Throw the eggs!
15. Re:Incidentally... by K.+S.+Kyosuke · 2012-05-25 03:53 · Score: 1
  
  Earth's orbit will become more and more elliptical over time and will eventually either slingshot Earth out of the orbit and directly into the Sun.
  You can't slingshot unless you have three bodies. Sun, Earth...and what is the third one, larger than Earth, that Earth regularly approaches?
  
  --
  Ezekiel 23:20
16. Re:Incidentally... by tqk · 2012-05-25 04:35 · Score: 1
  
  You can't slingshot unless you have three bodies.
  Pardon? How about we think of it as Earth falling into the Sun's gravity well far enough to be accelerated but not far enough to be captured. What happens next? I'd guess Earth gets flung off into the Oort cloud. That sounds like a two body slingshot effect to me.
  
  --
  "Tongue tied and twisted, just an Earth bound misfit ..." -- Pink Floyd.
17. Re:Incidentally... by K.+S.+Kyosuke · 2012-05-25 06:12 · Score: 1
  
  You know what? Continue attending your high school and return back to me after you will have studied the law of conservation of energy. Look out especially for mechanical energy and its exchange between potential and kinetic form for a body on a free fall trajectory.
  
  --
  Ezekiel 23:20
18. Re:Incidentally... by Anonymous Coward · 2012-05-25 06:32 · Score: 0
  
  AARRRGGH!!!! Too much stupid!
  From now on, I shall trust no /.ers over 5 digit UID.
19. Re:Incidentally... by schroedingers_hat · 2012-05-25 08:02 · Score: 1
  
  Sunspots go up, sunspots go down..
  
  You can't explain that.
20. Re:Incidentally... by schroedingers_hat · 2012-05-25 08:05 · Score: 2
  
  UUID goes up, intelligence goes down.
  You can't explain that.
21. Re:Incidentally... by Anonymous Coward · 2012-05-25 12:18 · Score: 0
  
  Sunspots go up, sunspots go down..
  You can't explain that.
  Assuming he is meaning the number of sunspots, then yes they can explain why the number goes up and down.
  Due to the rotational differences, the equator rotates quicker than the poles, it causes the magnetic fields to get bent and twisted. The bent and twisted magnetic fields are what create sun spots. Over ~11 years they get so twisted that they begin to 'snap' and reset back to an untwisted state, that creates the solar low points as they begin to reset. Of course the rotational difference is still there so the newly reset fields start to distort again bringing a new high until they start to 'snap' again to the next low.
22. Re:Incidentally... by davester666 · 2012-05-25 17:27 · Score: 1
  
  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.
  
  --
  Sleep your way to a whiter smile...date a dentist!
Manned Mission Needed by Scarletdown · 2012-05-24 19:15 · 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.

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This space unintentionally left blank.
1. Re:Manned Mission Needed by Black+Parrot · 2012-05-24 19:31 · Score: 3, Funny
  
  Or during an eclipse.
  
  --
  Sheesh, evil *and* a jerk. -- Jade
2. Re:Manned Mission Needed by Grayhand · 2012-05-24 20:22 · 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.
3. Re:Manned Mission Needed by Scarletdown · 2012-05-24 20:34 · Score: 1
  
  If doing it during an eclipse, it may be worthwhile to measure the sun's corona. Even better though would be to measure its Alaskan Amber.
  
  --
  This space unintentionally left blank.
4. Re:Manned Mission Needed by qu33ksilver · 2012-05-24 20:37 · Score: 4, Funny
  
  Or during Winter.. You know this was a yahoo question. http://answers.yahoo.com/question/index?qid=20120430182228AAIk7uw
5. Re:Manned Mission Needed by knarf · 2012-05-24 23:28 · Score: 1
  
  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.
  Who needs astronauts and tape measures when you have Three Wolf Moon? That moon don't look no bigger than a wolfs head, and wolfs we have a'plenty 'round here. Just grab one of 'm, measure its head and viola (sic).
  
  --
  --frank[at]unternet.org
6. Re:Manned Mission Needed by __aaltlg1547 · 2012-05-25 00:56 · Score: 4, Funny
  
  Everybody knows a Corona is 12 ounces.
7. Re:Manned Mission Needed by Scarletdown · 2012-05-25 06:42 · Score: 1
  
  Or during Winter.. You know this was a yahoo question. http://answers.yahoo.com/question/index?qid=20120430182228AAIk7uw
  
  Well, mine was inspired by a quip in an old indy comic back in the late 80s or early 90s called Space Ark. The bit there was:
  "How can we get close enough to the sun without burning up?"
  "Simple. We go at night."
  As for the Yahoo Answers post, I found it hilarious... hilarious that so many people actually thought the OP was being serious instead of seeing it for the silliness that it is.
  
  --
  This space unintentionally left blank.
8. Re:Manned Mission Needed by Scarletdown · 2012-05-25 06:44 · Score: 1
  
  Just grab one of 'm, measure its head and viola (sic).
  Just don't forget that afterward, there is always room for cello.
  
  --
  This space unintentionally left blank.
9. Re:Manned Mission Needed by wavedeform · 2012-05-25 09:13 · Score: 1
  
  I'm more interested in its exact Trumer Pils, myself.
Wouldn't it be great... by Nkwe · 2012-05-24 19:17 · Score: 0

...if TFA were in the same language as the TFS?
1. Re:Wouldn't it be great... by Nkwe · 2012-05-24 19:19 · Score: 1
  
  Sorry about the extra "the". It is late.
2. Re:Wouldn't it be great... by Anonymous Coward · 2012-05-24 19:27 · Score: 0
  
  Its not too much to ask everyone to learn every language. There can only be 3 or 4, right?
3. Re:Wouldn't it be great... by Anonymous Coward · 2012-05-24 19:33 · Score: 0
  
  Oh sure.. just let me go out and learn all 6900+ living languages - then you can publish in whichever language you want...
  Alternatively, everyone could learn the same second language and publish in that. Which one of the options do you think makes more sense...?
4. Re:Wouldn't it be great... by Black+Parrot · 2012-05-24 19:34 · 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
5. Re:Wouldn't it be great... by Baron+Eekman · 2012-05-24 20:14 · Score: 3, Informative
  
  English language version:
  http://ajw.asahi.com/article/behind_news/social_affairs/AJ201205250024
6. Re:Wouldn't it be great... by Anonymous Coward · 2012-05-24 23:39 · Score: 0
  
  I know you say everyone should be able to puplish in the language of their choice, but don't you think there's a huge different between them puplishing in their on language vs puplishing in their off language?
7. Re:Wouldn't it be great... by mcgrew · 2012-05-25 04:09 · Score: 1
  
  So, how many languages do YOU speak?
  
  --
  Free Martian Whores!
8. Re:Wouldn't it be great... by niado · 2012-05-25 05:58 · Score: 1
  
  whoosh..?
Sorry, can't resist. by jtownatpunk.net · 2012-05-24 19:31 · Score: 3, Funny

That's a relatively open weave and I can still see your... annular area.
Currently in use by zmooc · 2012-05-24 19:43 · Score: 3, Funny

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

--
0x or or snor perron?!
Just jump through the Flaming Hoop of Death.... by rts008 · 2012-05-24 19:54 · Score: 1

Your method suggests that extreme accuracy is required.
You don't want to be off-center, otherwise you might singe your tail feathers.....;-)

--
Down With Slashdot BETA!!! I've been around the corner and seen the oliphant; you can only abuse me from your perspecti
Wasn't this already known? by Anonymous Coward · 2012-05-24 19:56 · Score: 3, Informative

NASA seemed to know it's 696,000km long before this experiment.
1. Re:Wasn't this already known? by IWannaBeAnAC · 2012-05-24 22:32 · Score: 1
  
  Indeed. And the value elsewhere http://solarsystem.nasa.gov/planets/profile.cfm?Object=Sun&Display=Facts&System=Metric of 6.9551 x 10^5 km implies also an error of the order of 10km. But it differs by 500km (or 50 standard deviations)! This is an incredibly large difference between the measurements, given the error bars. Perhaps they are measuring different things, the radius at the equator won't be the same as the radius at the poles.
I missed it by The+Evil+Atheist · 2012-05-24 20:09 · Score: 4, Funny

Oh well, look on the bright side...

--
Those who do not learn from commit history are doomed to regress it.
Oh my god by Anonymous Coward · 2012-05-24 20:14 · 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.
1. Re:Oh my god by Anonymous Coward · 2012-05-24 23:59 · Score: 0
  
  The sun did change its size during history, but the latest is 3/5: http://en.wikipedia.org/wiki/Flag_of_Japan.
2. Re:Oh my god by The+Evil+Atheist · 2012-05-25 23:14 · Score: 1
  
  We should stop now while there's still some Sun left.
  Too late. The remainder of Sun is too busy suing Google...
  
  --
  Those who do not learn from commit history are doomed to regress it.
Define 'Sun' by EasyTarget · 2012-05-24 21:20 · Score: 3, Interesting

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 ;-)

--
"Oops, I always forget the purpose of competition is to divide people into winners and losers." - Hobbes
1. Re:Define 'Sun' by Anonymous Coward · 2012-05-24 21:50 · Score: 0
  
  Not to mention that it's probably not a perfect sphere, so a single radius doesn't capture its size.
2. Re:Define 'Sun' by mister_playboy · 2012-05-24 22:35 · Score: 3, Informative
  
  Not to mention that it's probably not a perfect sphere, so a single radius doesn't capture its size.
  Wikipedia sayth:
  
  It is a near-perfect sphere, with an oblateness estimated at about 9 millionths, which means that its polar diameter differs from its equatorial diameter by only 10 km. As the Sun consists of a plasma and is not solid, it rotates faster at its equator than at its poles. This behavior is known as differential rotation, and is caused by convection in the Sun and the movement of mass, due to steep temperature gradients from the core outwards. This mass carries a portion of the Sun’s counter-clockwise angular momentum, as viewed from the ecliptic north pole, thus redistributing the angular velocity. The period of this actual rotation is approximately 25.6 days at the equator and 33.5 days at the poles. However, due to our constantly changing vantage point from the Earth as it orbits the Sun, the apparent rotation of the star at its equator is about 28 days. The centrifugal effect of this slow rotation is 18 million times weaker than the surface gravity at the Sun's equator. The tidal effect of the planets is even weaker, and does not significantly affect the shape of the Sun.
  So more round than you might think. :)
  
  --
  Do what thou wilt shall be the whole of the Law ::: Love is the law, love under will
3. Re:Define 'Sun' by Hentes · 2012-05-26 04:02 · Score: 1
  
  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.
4. Re:Define 'Sun' by Anonymous Coward · 2012-05-27 09:57 · Score: 0
  
  Generally this sort of work is done on a per-wavelength basis. When we look at exoplanets and measure their radii based on transits, the transit depth changes dependent on the composition of the atmopshere (which necessarily varies in opacity).
  I suspect there is a standard definition like the height at which the atmospheric density drops to 1/e^n of the density in the core or whatever (i.e. scale heights). It's a similar problem to how we define where Earth stops and where Space begins.
How accurate can it be ? by Alain+Williams · 2012-05-24 21:47 · Score: 4, Insightful

Is this not somewhat akin to trying to measure the depth of a saucepan of boiling water ?
1. Re:How accurate can it be ? by MalachiK · 2012-05-24 22:00 · Score: 2
  
  Yeah, but I'd guess it's pretty smooth when you consider the radius of the sun is of the order 10^9 m.
Re:first post dudes! by Anonymous Coward · 2012-05-25 00:40 · Score: 0

Not true. I have been lurking and posting here since the beginning of time.
In related news... by clickety6 · 2012-05-25 00:42 · Score: 1

... 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!"

--
----------------------------------- My Other Sig Is Hilarious -----------------------------------
Article unintelligible by __aaltlg1547 · 2012-05-25 00:52 · Score: 1

Can we get it translated from the original Japanese to English by a person who speaks both languages fluently?
1. Re:Article unintelligible by VortexCortex · 2012-05-25 01:28 · Score: 1
  
  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!"
Best solar radius ever made by Anonymous Coward · 2012-05-25 01:05 · Score: 0

Sorry if somebody already posted it, but the best solar optical radius ever made was accomplished by a team of the SoHO satellite. They obtained a value of (960.12 ± 0.09) arc sec or (696,342 ± 65) km. See "Measuring the Solar Radius from Space during the 2003 and 2006 Mercury Transits", Marcelo Emilio, Jeff R. Kuhn, Rock I. Bush, Isabelle F. Scholl. Read the complete work in the following link: http://arxiv.org/abs/1203.4898
Guigue
Measured using known dimensions? by n7ytd · 2012-05-25 02:25 · Score: 2

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!
1. Re:Measured using known dimensions? by Anonymous Coward · 2012-05-25 06:44 · Score: 0
  
  I puzzled for a while as to what they meant -- The obvious fix "using the known size and distance from the Earth to the Moon" isn't enough to accomplish it.
  I think it was initially "using the known size and distance of the Moon, and distance from the Earth to the sun", and a typist skipped from one "and distance" to the next (and botched "to" into "of")...
Asteroid Occultation Timing by Anonymous Coward · 2012-05-25 03:25 · Score: 0

This is kind of like timing asteroid occultations, but for the opposite purpose. An asteroid will blot out a star for a few seconds. By precisely recording the time and location, you are effectively measuring a chord of the asteroid's "shadow" cast by that dim star. Astronomers can use the data to determine the size, shape, and rotation of the asteroid. This crowdsourcing effort is just about the last area of astronomy where a backyard amateur can really contribute to science.
In this case, the participants were looking for the effect when the edge of the sun is peaking through the texture of the moon's edge, creating "beads" that prove they are precicely aligned on that edge. But instead of using the info to measure the asteroid (moon) they can use it to measure the star (sun).
I agree that the article could have been better written or translated. I'm sure astronomers can determine the angular measure of the sun directly with extremely high precision.
I'm still sore that it rained where I live by mark-t · 2012-05-25 03:26 · Score: 1

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 hates me.

--
File under 'M' for 'Manic ranting'
1. Re:I'm still sore that it rained where I live by Anonymous Coward · 2012-05-25 05:36 · Score: 0
  
  I am sorry you didn't get to see it. Here in sunny california we had 96% coverage with no clouds, it was amazing! So to sum it all up, yes the universe does hate you.
Correction Factors? by xfade551 · 2012-05-25 03:43 · Score: 1

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.
1. Re:Correction Factors? by Anonymous Coward · 2012-05-25 07:24 · Score: 0
  
  Have a better handle on how to treat the data for correct answer? Yes, possibly (though I expect there were some similarly qualified professionals involved in this, so they may have done it all correctly anyway).
  Have a better handle on the exact diameter? If so, only because of the better corrections (which can be applied to this data) -- there's no way they've got a better set of raw data than this.
×10^6 by Anonymous Coward · 2012-05-25 11:24 · Score: 0

Change article as one may start believing that Sun is much smaller than Earth and even smaller than Moon...
Whole story is junk by Old+Wolf · 2012-05-25 13:17 · Score: 1

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