Skip to comments.How Big is the Sun, Really?
Posted on 03/23/2012 1:29:41 AM PDT by U-238
With all the attention that astronomers have lavished on old Sol over the centuries, you'd think that by now they'd know its diameter to, oh, 10 or 12 significant digits.
During the past 40 years, astronomers have attempted to measure the Sun's sizedozens of times using various methods. The dashed line corresponds to a radius of 696,000 km, the value most often used.
While the Sun's girth has indeed been measured dozens of times over the past 40 years, the results haven't converged on a single value and scatter by as much as ± 0.1%. One big reason is that, though some measurement techniques are extremely precise, their accuracy suffers because of the turbulence induced by Earth's atmosphere. Most often astronomers use a compromise value of 865,000 miles (1,392,000 km).
So Marcelo Emilio (State university of Ponta Grossa, Brazil) has teamed with observers at the University of Hawaii and Stanford to approach this measurement with, literally, space-age techniques. They used images taken by the Michelson Doppler Imager (MDI) aboard NASAs Solar and Heliospheric Observatory (SOHO), homing in on transits of the planet Mercury across the solar disk in 2003 and 2006.
This makes perfect sense. The spacecraft sits at the L1 Lagrange point, a million miles from Earth, and Mercury has nothing but the barest wisps of atmosphere a made-to-order combination for crisp images.
(Excerpt) Read more at skyandtelescope.com ...
Earth's atmosphere? What can cause that? Must be Earth's Anthropomorphic Turbulence... or EAT! Only one way to deal with that... might take many Trillion$, but we gotta do it. Do we have consensus yet?
That's an easy one:
It's about the size of a grapefruit...
I like it..
That kinda reminds me of my last prostate exam.
Even though the sun is so far away, it manages to have a major effect on our lives here at Earth. Within the next hour, it is going to appear once again on the eastern horizon here in New England - at least I hope it does, otherwise we are in for one hell of a dark, cold day here.
Vote Republican in November and you can kiss the ground goodbye.
The sun is a big ball of hot gas - it does not have a sharply defined circumference and hence no precise diameter.
I’ve always wanted to know just how big the sun is. Within 0.1%.
That's why there is no Climate Science - those claiming to be "Climate Scientists" can't even predict the sign much less the magnitude.
I’m going to go out on a limb here and suggest a ball of hydrogen plasma 850,000 miles in diameter with a fusion reaction core converting tons of matter per second just might be larger factor in global warming than my SUV.
I tried to measure it a couple of times, but my tape measure kept melting.
You should have measured it from the dark side.
What are they measuring it for, a tuxedo? Just leave a few extra inches in the waist and it’ll be fine.
I don't believe there was a total solar eclipse during 1969. Where did you see this? There was an annular eclipse in 1969, but seeing that would have led you to conclude that the sun is bigger than the moon!
(I've been in the path of totality twice, but the only total eclipse I actually saw was on March 7, 1970, on Nantucket Island.)
“the only total eclipse I actually saw was on March 7, 1970, on Nantucket Island”
Did you fly your Lear Jet up there? Geez you’re vain.. You probably think this post is about you.
They seem to be assuming that it has a constant diameter. Isn’t it possible that the sun’s diameter changes from time to time? As a great big ball of burning gas and plasma it might swell up and contract back again, if only a little, every now and then.
And why exactly do we need to know this with such precision? Are we buying it a new pair of pants?