APOD: Detailed View of a Solar Eclipse Corona (2024 Apr 02)

[APOD Robot]

Detailed View of a Solar Eclipse Corona

Explanation: Only in the fleeting darkness of a total solar eclipse is the light of the solar corona easily visible. Normally overwhelmed by the bright solar disk, the expansive corona, the sun's outer atmosphere, is an alluring sight. But the subtle details and extreme ranges in the corona's brightness, although discernible to the eye, are notoriously difficult to photograph. Pictured here, however, using multiple images and digital processing, is a detailed image of the Sun's corona taken during the April 20, 2023 total solar eclipse from Exmouth, Australia. Clearly visible are intricate layers and glowing caustics of an ever changing mixture of hot gas and magnetic fields. Bright looping prominences appear pink just around the Sun's limb. A similar solar corona might be visible through clear skies in a narrow swath across the North America during the total solar eclipse that occurs just six days from today

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[SpaceCadet]

How far out do the petals of the corona extend? They seem huge.

[Locutus76]

How far out do the petals of the corona extend? They seem huge.

Given that the sun is about 1.4 million Kilometer (865 m Mi) in diameter, they appear to be at least 1.5 mK long, depending on what is considered the edge of the ‘petals’.

[Christian G.]

How far out do the petals of the corona extend? They seem huge.

Not sure if this is a correct way to put it but solar wind is the corona spreading ever further out into space, so even we here on Earth are in a sense bathing in the Sun's corona! Luckily it has cooled down on the way.

[Chris Peterson]

How far out do the petals of the corona extend? They seem huge.

Not sure if this is a correct way to put it but solar wind is the corona spreading ever further out into space, so even we here on Earth are in a sense bathing in the Sun's corona! Luckily it has cooled down on the way.

While the density of the coronal material (the solar wind) is much reduced by the time it reaches Earth, its temperature is about the same: 1 million K.

[Christian G.]

How far out do the petals of the corona extend? They seem huge.

Not sure if this is a correct way to put it but solar wind is the corona spreading ever further out into space, so even we here on Earth are in a sense bathing in the Sun's corona! Luckily it has cooled down on the way.

While the density of the coronal material (the solar wind) is much reduced by the time it reaches Earth, its temperature is about the same: 1 million K.

And why exactly is this corona so friggin' hot?! Seriously I am baffled that it should be so much hotter than the very surface of the Sun. Like a fireplace that somehow produces way more heat in your living room than right next to its flames!

[MelvzLuster]

Nice photo, thanks for sharing, keep it up & more success!

[Chris Peterson]

Not sure if this is a correct way to put it but solar wind is the corona spreading ever further out into space, so even we here on Earth are in a sense bathing in the Sun's corona! Luckily it has cooled down on the way.

While the density of the coronal material (the solar wind) is much reduced by the time it reaches Earth, its temperature is about the same: 1 million K.

And why exactly is this corona so friggin' hot?! Seriously I am baffled that it should be so much hotter than the very surface of the Sun. Like a fireplace that somehow produces way more heat in your living room than right next to its flames!

The mechanism or mechanisms involved in heating the corona are very poorly understood. It's a plasma, which means it is influenced by magnetic fields. It is presumed that some kind of coupling is occurring in the corona with solar magnetic fields which is inducing currents and other phenomena that transfer energy. It doesn't actually take that much energy, given that the corona is a million times less dense than the solar surface- effectively a pretty hard vacuum.

[Christian G.]

While the density of the coronal material (the solar wind) is much reduced by the time it reaches Earth, its temperature is about the same: 1 million K.

And why exactly is this corona so friggin' hot?! Seriously I am baffled that it should be so much hotter than the very surface of the Sun. Like a fireplace that somehow produces way more heat in your living room than right next to its flames!

The mechanism or mechanisms involved in heating the corona are very poorly understood. It's a plasma, which means it is influenced by magnetic fields. It is presumed that some kind of coupling is occurring in the corona with solar magnetic fields which is inducing currents and other phenomena that transfer energy. It doesn't actually take that much energy, given that the corona is a million times less dense than the solar surface- effectively a pretty hard vacuum.

Thanks for your answer. A pretty good one for something poorly understood!

[AVAO]

How far out do the petals of the corona extend? They seem huge.

As the final countdown to the April 8 total solar eclipse approaches, use the Helioviewer Eclipse Watch tool to observe eclipse-like images that are captured over 100 times each day by the LASCO C2 coronagraph on the Solar and Heliospheric Observatory (SOHO), a joint NASA-ESA mission stationed one million miles from Earth:

Click to view full size image

https://eclipse.helioviewer.org/

[Ann]

I should have commented on this APOD before, because it is really stunning!

Detailed View of a Solar Eclipse Corona. Image Credit & Copyright: Phil Hart

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So these are my questions. Are the long straight lines magnetic lines, where particles rush out away from the Sun into the outer parts of the solar system?

Why does the corona also form "petal" structures?

Do we see magnetic loops at the Sun's limb?

Does the pink stuff that we see at the Sun's limb at left get its color from Hα? If not, why is it pink?

Is the corona actually blue-white? I find the color magical.

Ann

[Christian G.]

Is the corona actually blue-white? I find the color magical.

Ann

I feel so lucky to be able to say: I'll tell you next week! (I live in the path of totality)

[Chris Peterson]

I should have commented on this APOD before, because it is really stunning!

Detailed View of a Solar Eclipse Corona. Image Credit & Copyright: Phil Hart

---

APOD 2 April 2024 annotated.png

So these are my questions. Are the long straight lines magnetic lines, where particles rush out away from the Sun into the outer parts of the solar system?

Why does the corona also form "petal" structures?

Do we see magnetic loops at the Sun's limb?

Does the pink stuff that we see at the Sun's limb at left get its color from Hα? If not, why is it pink?

Is the corona actually blue-white? I find the color magical.

Ann

The red/pink is H-alpha. The corona in actuality is colorless, giving the impression of silver white.

[Christian G.]

The red/pink is H-alpha.

Is that to say that upon seeing the red/pink during totality, we are seeing with our own eyes the actual H-alpha colours of distant pink/red nebulae?

[Chris Peterson]

The red/pink is H-alpha.

Is that to say that upon seeing the red/pink during totality, we are seeing with our own eyes the actual H-alpha colours of distant pink/red nebulae?

The Sun is made of hot hydrogen. That hydrogen is emitting the same red light we see in emission nebulas. But where its gas is optically thick (what we call the "surface") it is a blackbody (thermal) source of white light that is a million times brighter than the narrowband hydrogen emissions. An eclipse blocks the bright white light so we can see any glowing hydrogen being carried above the surface (prominences). It's the same thing we see when we view the Sun through a filter that isolates the hydrogen emission line (except in that case we can see the entire surface, not just prominences above it).

(The color we see is a narrow line at 656 nm, which is deep ruby red. In nebulas we always see it photographically, and usually mixed with other colors from reflections and the emissions of other elements. That, combined with processing techniques, means we see it as a range of reddish colors covering pink, magenta, and others. But visually, when there's no other light? It's red. That's what I saw during this eclipse, and every other eclipse where the Sun has been active enough to have high prominences. No pink, but intense, deep red.)

[Christian G.]

The red/pink is H-alpha.

Is that to say that upon seeing the red/pink during totality, we are seeing with our own eyes the actual H-alpha colours of distant pink/red nebulae?

The Sun is made of hot hydrogen. That hydrogen is emitting the same red light we see in emission nebulas. But where its gas is optically thick (what we call the "surface") it is a blackbody (thermal) source of white light that is a million times brighter than the narrowband hydrogen emissions. An eclipse blocks the bright white light so we can see any glowing hydrogen being carried above the surface (prominences). It's the same thing we see when we view the Sun through a filter that isolates the hydrogen emission line (except in that case we can see the entire surface, not just prominences above it).

(The color we see is a narrow line at 656 nm, which is deep ruby red. In nebulas we always see it photographically, and usually mixed with other colors from reflections and the emissions of other elements. That, combined with processing techniques, means we see it as a range of reddish colors covering pink, magenta, and others. But visually, when there's no other light? It's red. That's what I saw during this eclipse, and every other eclipse where the Sun has been active enough to have high prominences. No pink, but intense, deep red.)

Thank you for this most complete answer!

[VLL]

Are these images Original?