Starship Asterisk*

SpaceCadet wrote: ↑Tue Apr 02, 2024 8:38 am How far out do the petals of the corona extend? They seem huge.

SpaceCadet wrote: ↑Tue Apr 02, 2024 8:38 am How far out do the petals of the corona extend? They seem huge.

Christian G. wrote: ↑Tue Apr 02, 2024 12:18 pm

SpaceCadet wrote: ↑Tue Apr 02, 2024 8:38 am 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 wrote: ↑Tue Apr 02, 2024 1:16 pm

Christian G. wrote: ↑Tue Apr 02, 2024 12:18 pm

SpaceCadet wrote: ↑Tue Apr 02, 2024 8:38 am 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. wrote: ↑Tue Apr 02, 2024 2:28 pm

Chris Peterson wrote: ↑Tue Apr 02, 2024 1:16 pm

Christian G. wrote: ↑Tue Apr 02, 2024 12:18 pm
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!

Chris Peterson wrote: ↑Tue Apr 02, 2024 2:39 pm

Christian G. wrote: ↑Tue Apr 02, 2024 2:28 pm

Chris Peterson wrote: ↑Tue Apr 02, 2024 1:16 pm

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.

SpaceCadet wrote: ↑Tue Apr 02, 2024 8:38 am How far out do the petals of the corona extend? They seem huge.

Ann wrote: ↑Wed Apr 03, 2024 4:46 am
Is the corona actually blue-white? I find the color magical.

Ann

Ann wrote: ↑Wed Apr 03, 2024 4:46 am 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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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

Chris Peterson wrote: ↑Wed Apr 03, 2024 4:19 pm
The red/pink is H-alpha.

Christian G. wrote: ↑Wed Apr 10, 2024 12:58 pm

Chris Peterson wrote: ↑Wed Apr 03, 2024 4:19 pm
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 wrote: ↑Wed Apr 10, 2024 1:25 pm

Christian G. wrote: ↑Wed Apr 10, 2024 12:58 pm

Chris Peterson wrote: ↑Wed Apr 03, 2024 4:19 pm
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.)