APOD: Total Solar Eclipse Corona in HDR (2018 Apr 30)

[APOD Robot]

Total Solar Eclipse Corona in HDR

Explanation: How great was the Great American Eclipse? The featured HDR image shows it to be perhaps greater than we knew. On August 21 of last year, the Moon blocked the Sun for a few minutes along a narrow path across the USA. Although one of the most photographed events in human history, this image -- only recently completed after an extraordinary amount of digital processing -- shows one of the most detailed depictions of a solar corona ever taken. Composed of extremely hot gas, the solar corona is only visible to the unaided eye during a total solar eclipse. The featured image combined over 70 images of different time exposures. The series of complementary HDR images recovered enough detail to see motion of the solar corona. The images were taken in Unity, Oregon in the morning to get steady atmospheric seeing conditions. The next total solar eclipse visible on Earth will be in 2019 July, while the next one visible across North America and the USA will occur in 2024 April.

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[Roger]

Wonderfull! I really enjoy this one.
But could you explain what are the two bright dots on top left?
Thank you

[Wah!]

The best of the best!

[DAMGEM]

The smaller one looks to be a double star and the flared light I am going to guess is reflected light off a solar panel.

[Joe Stieber]

But could you explain what are the two bright dots on top left?

They are stars, the brighter one is Regulus (Alpha Leonis) and the fainter one is TYC 833-134-1. See Jerry Lodriguss’ page at...

http://www.astropix.com/eclipse/2017_To ... shine.html

Be sure to check out some of Jerry’s other eclipse pictures linked off the “index page” at...

http://www.astropix.com/eclipse/2017_To ... Index.html

[heehaw]

"... will be in 2019 July" Oh, how I approve of THAT way of expressing the time! For example, today is: 2018 April 30 Monday. And not 4/30/18 which is our usual American way: leading to dates such as 1/3/9. And in England I believe one writes 30/4/18 ?

[orin stepanek]

Powerful! What a beautiful picture of Old Sol!

[Guest]

"... will be in 2019 July" Oh, how I approve of THAT way of expressing the time! For example, today is: 2018 April 30 Monday. And not 4/30/18 which is our usual American way: leading to dates such as 1/3/9. And in England I believe one writes 30/4/18 ?

Speak for yourself, I personally had a blast writing checks on 11-11-11 !!!

[RJN]

Because the Sun was not visible in the Hubble Deep Field (HDF) during these exposures, the title of this APOD has had "HDF" changed to "HDR" (high dynamic range) in the NASA APOD version. I apologize for the oversight. - RJN

[MarkBour]

That's no moon ... it looks like the Death Star, just beginning to explode!

Seriously, I love those detailed wave patterns in the Corona. Also, the motion observable in the "motion of the solar corona" link.

Think about Albert Einstein's famous request, what is the star closest to the Sun that anyone photographed during this eclipse, I wonder?
In this image, I see one at about the 8-o'clock position, but it is not very close in.

[neufer]

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Think about Albert Einstein's famous request, what is the star closest to the Sun that anyone photographed during this eclipse, I wonder?

In this image, I see one at about the 8-o'clock position, but it is not very close in.

Due to atmospheric distortion no one has improved all that much on Eddington using visible light from the ground (and getting closer to the Sun doesn't help a lot).

[Craig Willford]

I had read in advance of the eclipse that if it was my first (it was) then I shouldn't bother trying to photograph it, but rather just enjoy it. The idea is that there will be people with better equipment and more experience than I and they will be sharing their pictures over the internet. Boy, was that good advice! The ten people who shared the quick views through my 10" richest field telescope (f/4) all enjoyed it greatly. None of us tried to take a picture. What an experience!

[FLPhotoCatcher]

Looking at the magnetic field lines, I notice a big difference between them near the poles vs equator. It seems like any charged particles escaping the sun near the equator would be moving slower because they would have to cross the magnetic field lines in a more perpendicular direction. And don't the denser magnetic field lines near the equator attract charged particles from the more polar regions? Might these things explain the barrel shape of "planetary nebulae"?

[neufer]

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Looking at the magnetic field lines, I notice a big difference between them near the poles vs equator. It seems like any charged particles escaping the sun near the equator would be moving slower because they would have to cross the magnetic field lines in a more perpendicular direction. And don't the denser magnetic field lines near the equator attract charged particles from the more polar regions? Might these things explain the barrel shape of "planetary nebulae"?

Ulysses observations of solar wind speed as a function of helio latitude during solar minimum. Slow wind (~400 km/s) is confined to the equatorial regions, while fast wind (~750 km/s) is seen over the poles. Red/blue colours show inward/outward polarities of the heliospheric magnetic field.

[FLPhotoCatcher]

Thanks for the info. So I wonder if the differing solar wind is the explanation for the shape of most planetary nebulae.

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Ulysses observations of solar wind speed as a function of helio latitude during solar minimum. Slow wind (~400 km/s) is confined to the equatorial regions, while fast wind (~750 km/s) is seen over the poles. Red/blue colours show inward/outward polarities of the heliospheric magnetic field.

[alter-ego]

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Think about Albert Einstein's famous request, what is the star closest to the Sun that anyone photographed during this eclipse, I wonder?

In this image, I see one at about the 8-o'clock position, but it is not very close in.

Due to atmospheric distortion no one has improved all that much on Eddington using visible light from the ground (and getting closer to the Sun doesn't help a lot).

Well not so anymore.

Precise starlight positions near the sun were measured during the 21 August 2017 total solar eclipse in order to measure their gravitational deflections. The equipment, procedures, and analysis are described in detail. A portable refractor, a CCD camera, and a computerized mount were set up in Wyoming. Detailed calibrations were necessary to improve accuracy and precision. Nighttime measurements taken just before the eclipse provided cubic optical distortion corrections. Calibrations based on star field images 7.4 deg on both sides of the sun taken during totality gave linear and quadratic plate constants. A total of 45 images of the sky surrounding the Sun were acquired during the middle part of totality, with an integrated exposure of 22 seconds. The deflection analysis depended on accurate star positions from the USNO's UCAC5 star catalog. The final result was a deflection coefficient L = 1.752 arcsec, compared to the theoretical value of L = 1.751 arcsec, with an uncertainty of only 3%.
...
The recent 21 August 2017 total solar eclipse across the United States provided a convenient opportunity to repeat this experiment. This paper reports successful starlight deflection measurements performed in Wyoming using high quality amateur astronomical equipment. The final results show the most precise and accurate measurements of this kind ever reported.

Done with 100mm aperture (stopped down to 87mm), and 543mm focal length, (comparison images taken within 1 minute before and after totality) these results are 2x better that the best previous measurements made in the 60's and 70's when the best technology provided "large photographic plates (0.2 m to 0.45 m), long refractor telescopes (1.5 m to 8.5 m focal length), and comparison images taken with the same telescope a few months before or after the eclipse to determine non-perturbed star positions."

Nice work by Donald Bruns. The S&T article: A Picture-Perfect Solar Eclipse Experiment by D. Bruns is informative and an easy read.

[DAMGEM]

THIS WONDERFUL IMAGE HAS CAPTURED OTHER NICE SOLAR FEATURES.
IS THAT A CME HOVERING BESIDE THE BOTTOM LEFT QUADRANT OF THE
MOON OR JUST SUSPENDED PLASMA.

[neufer]

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Precise starlight positions near the sun were measured during the 21 August 2017 total solar eclipse in order to measure their gravitational deflections. The equipment, procedures, and analysis are described in detail. A portable refractor, a CCD camera, and a computerized mount were set up in Wyoming. Detailed calibrations were necessary to improve accuracy and precision. Nighttime measurements taken just before the eclipse provided cubic optical distortion corrections. Calibrations based on star field images 7.4 deg on both sides of the sun taken during totality gave linear and quadratic plate constants. A total of 45 images of the sky surrounding the Sun were acquired during the middle part of totality, with an integrated exposure of 22 seconds. The deflection analysis depended on accurate star positions from the USNO's UCAC5 star catalog. The final result was a deflection coefficient L = 1.752 arcsec, compared to the theoretical value of L = 1.751 arcsec, with an uncertainty of only 3%.
...
The recent 21 August 2017 total solar eclipse across the United States provided a convenient opportunity to repeat this experiment. This paper reports successful starlight deflection measurements performed in Wyoming using high quality amateur astronomical equipment. The final results show the most precise and accurate measurements of this kind ever reported.

Done with 100mm aperture (stopped down to 87mm), and 543mm focal length, (comparison images taken within 1 minute before and after totality) these results are 2x better that the best previous measurements made in the 60's and 70's when the best technology provided "large photographic plates (0.2 m to 0.45 m), long refractor telescopes (1.5 m to 8.5 m focal length), and comparison images taken with the same telescope a few months before or after the eclipse to determine non-perturbed star positions."

Nice work by Donald Bruns. The S&T article: A Picture-Perfect Solar Eclipse Experiment by D. Bruns is informative and an easy read.

The convergence to Brun's constant ≈ 1.902160583104.

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<<In number theory, Brun's theorem states that the sum of the reciprocals of the twin primes (pairs of prime numbers which differ by 2) converges to a finite value known as Brun's constant, usually denoted by B2 (sequence A065421 in the OEIS). Brun's theorem was proved by Viggo Brun in 1919, and it has historical importance in the introduction of sieve methods. In 2002 Pascal Sebah and Patrick Demichel used all twin primes up to 10¹⁶ to give the estimate:

B2 ≈ 1.902160583104 =

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