When asked to recount an experience from the Apollo program, Neil Armstrong stated:

[My] most indelible memory was approaching the moon and flying through the moon shadows so that the moon was eclipsing the sun and we could see the corona all around the moon. It was not circular, it was elliptical which was a big surprise, I didn't understand that. And then we could see the moon - the dark side of the moon of course, illuminated by earth-light...

This quote was taken from podcast StarTalk Radio, S1:EP9, "Anniversary of Apollo 11" starting at about 11:35. (Did my best to transcribe accurately).

In the quote, it seemed like Armstrong was referring to an unaided-eye observation. So why would the eclipse look different from his unique vantage point than an eclipse would have looked from Earth, which seemed to be what he was comparing to?

Here's what seems to be a typical solar eclipse as seen from Earth (source):

enter image description here

which overall seems to be circular; the irregularities don't seem obviously elliptical to me.

Presumably from Armstrong's vantage point, it didn't look like this.


Answer: The sun has an outrageously strong magnetic field. The corona is highly ionized and interacts with the magnetic field. This produces corona symmetry around the magnetic pole axis. The corona is not spherically symmetric.

I braved the world’s biggest traffic jam to witness the 2017 solar eclipse. I watched the corona with bare eyeballs through astronomic binoculars. Better than LSD (as described to me).

enter image description here https://www.forbes.com/sites/jamiecartereurope/2020/06/09/sherpas-unravel-secrets-of-the-suns-mysterious-corona-from-the-last-total-solar-eclipse/?sh=300c4f8c2f89

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    $\begingroup$ Is that a visible light image? Or a rendition of the magnetic field? or...? $\endgroup$ Jan 6 at 1:39
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    $\begingroup$ White light. It's from the 2019 eclipse I observed. This is identical to the view I had through binoculars. No filters. OMFG . Note you can still see features of the Moon's surface lit by Earthlight. forbes.com/sites/jamiecartereurope/2020/06/09/… $\endgroup$
    – Woody
    Jan 6 at 1:43
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    $\begingroup$ Interesting! Please add the source link to the answer. $\endgroup$ Jan 6 at 1:51
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    $\begingroup$ Correction: it was not the "last solar eclipse". it was the 2019 solar eclipse. The "last" eclipse was only visible in Antarctica. My buddy was down there (flying DC-3's). He texted a picture of himself doing a handstand beside the official South Pole (it looks like a barber pole) during the eclipse. $\endgroup$
    – Woody
    Jan 6 at 2:02
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    $\begingroup$ Re "This is identical to the view I had through binoculars": No, the prominences/protoburances are very clearly red, not white, no matter which eclipse (for example, first hand, from Wyoming, near Boysen Reservoir, 2017-08-21, through binoculars). $\endgroup$ Jan 6 at 17:10

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