APOD: Total Solar Eclipse 2020 (2021 Jan 07)

[APOD Robot]

Total Solar Eclipse 2020

Explanation: Along a narrow path crossing southern South America through Chile and Argentina, the final New Moon of 2020 moved in front of the Sun on December 14 in the year's only total solar eclipse. Within about 2 days of perigee, the closest point in its elliptical orbit, the New Moon's surface is faintly lit by earthshine in this dramatic composite view. The image is a processed composite of 55 calibrated exposures ranging from 1/640 to 3 seconds. Covering a large range in brightness during totality, it reveals the dim lunar surface and faint background stars, along with planet-sized prominences at the Sun's edge, an enormous coronal mass ejection, and sweeping coronal structures normally hidden in the Sun's glare. Look closely for an ill-fated sungrazing Kreutz family comet (C/2020 X3 SOHO) approaching from the lower left, at about the 7 o'clock position. In 2021 eclipse chasers will see an annular solar eclipse coming up on June 10. They'll have to wait until December 4 for the only total solar eclipse in 2021 though. That eclipse will be total along a narrow path crossing the southernmost continent of Antarctica.

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[DL MARTIN]

Is there an accounting of the energy transferred and subsequently stored as a result of earthshine, moonshine...?

[orin stepanek]

Ow; Ow; Ow! Hot; Hot: Hot!
Sun's coronal ejections reach way out!

[Eclectic Man]

Wow!

[Chris Peterson]

Is there an accounting of the energy transferred and subsequently stored as a result of earthshine, moonshine...?

The energy we receive from the corona amounts to a nearly unmeasurably small fraction of the energy from the Sun's surface.

[Mountainjim62]

Is there an explanation for why the corona looks distinctly different on the right & left side of the sun compared to the top & bottom of the sum in the image?

[Chris Peterson]

Is there an explanation for why the corona looks distinctly different on the right & left side of the sun compared to the top & bottom of the sum in the image?

The shape of the corona is highly influenced by the Sun's magnetic field.

[johnnydeep]

Is there an accounting of the energy transferred and subsequently stored as a result of earthshine, moonshine...?

The energy we receive from the corona amounts to a nearly unmeasurably small fraction of the energy from the Sun's surface.

I believe DL MARTIN was talking about the energy the moon receives from earthshine, and how much energy the earth receives from moonshine. Nothing to do with the sun's corona. I imagine the solar flux (in watts/m²) in either case is pretty small.

[Guest1000]

So many who have seen totality live say what impressed them most was the active motion visible, waves rippling out etc.
I have never seen it live.
I have never seen a video of this brief moment. All videos seem to show the entire eclipse from start to end, time lapses etc., but never just the most fascinating part.
Does anyone have any links of such a video?

[Chris Peterson]

Is there an accounting of the energy transferred and subsequently stored as a result of earthshine, moonshine...?

The energy we receive from the corona amounts to a nearly unmeasurably small fraction of the energy from the Sun's surface.

I believe DL MARTIN was talking about the energy the moon receives from earthshine, and how much energy the earth receives from moonshine. Nothing to do with the sun's corona. I imagine the solar flux (in watts/m²) in either case is pretty small.

Maybe. People have looked at the effect of earthshine at the Moon. The Moon receives about 75 mW per square meter from light reflected off the Earth, and another 75 mW per square meter from thermal radiation emitted by the Earth. So a total of 150 mW per square meter. Clearly, the Earth will receive much less than this from sunlight reflected directly from the Moon, and even less from earthshine. Given the Moon's low albedo, the direct energy contribution at Earth from a full Moon can't be more than a few tens of milliwatts per square meter at most, compared with over a kilowatt per square meter from direct sunlight.

[Chris Peterson]

So many who have seen totality live say what impressed them most was the active motion visible, waves rippling out etc.
I have never seen it live.
I have never seen a video of this brief moment. All videos seem to show the entire eclipse from start to end, time lapses etc., but never just the most fascinating part.
Does anyone have any links of such a video?

I have seen a number of total eclipses, and there is no motion. Nothing we see at this scale moves visibly in a few minutes of totality. There are a few dynamic effects created around the edges as the Moon blocks and exposes the surface of the Sun, but that is all. Any sense that things are moving is just an optical illusion... which is why we don't see it in videos.

[johnnydeep]

The energy we receive from the corona amounts to a nearly unmeasurably small fraction of the energy from the Sun's surface.

I believe DL MARTIN was talking about the energy the moon receives from earthshine, and how much energy the earth receives from moonshine. Nothing to do with the sun's corona. I imagine the solar flux (in watts/m²) in either case is pretty small.

Maybe. People have looked at the effect of earthshine at the Moon. The Moon receives about 75 mW per square meter from light reflected off the Earth, and another 75 mW per square meter from thermal radiation emitted by the Earth. So a total of 150 mW per square meter. Clearly, the Earth will receive much less than this from sunlight reflected directly from the Moon, and even less from earthshine. Given the Moon's low albedo, the direct energy contribution at Earth from a full Moon can't be more than a few tens of milliwatts per square meter at most, compared with over a kilowatt per square meter from direct sunlight.

Thanks for the numbers. I hadn't even thought about the light the earth receives from earthshine hitting the moon! Then there's the energy the moon receives from moonshine hitting the earth, and so on reflecting ad infinitum.

[Guest1000]

I have seen a number of total eclipses, and there is no motion. Nothing we see at this scale moves visibly in a few minutes of totality. There are a few dynamic effects created around the edges as the Moon blocks and exposes the surface of the Sun, but that is all. Any sense that things are moving is just an optical illusion... which is why we don't see it in videos.

Thank you very much! Always great to clear up misunderstandings!

[DL MARTIN]

In reference to my question regarding the transference and storage (absorption) of energy resulting from earthshine and moonshine, I neglected to include time as a variable. In addition, I'm not limiting my question to a parochial moon-earth thing. The question I've in mind is how much energy is exchanged and stored among celestial bodies, seemingly in a passive format, yet collectively of possible consequence, in the search for dark energy.

[johnnydeep]

In reference to my question regarding the transference and storage (absorption) of energy resulting from earthshine and moonshine, I neglected to include time as a variable. In addition, I'm not limiting my question to a parochial moon-earth thing. The question I've in mind is how much energy is exchanged and stored among celestial bodies, seemingly in a passive format, yet collectively of possible consequence, in the search for dark energy.

Well, probably 99.999% of all light emitted by stars is not absorbed by anything, near or far. But that thought makes me wonder how much energy in the form of protonsphotons and neutrinos is free flying throughout the universe. I'll take that number in watts/m³ please, Chris. (is that even the correct unit?)

EDIT: of course I meant photons above, not protons! Though I supposed there can indeed be free protons (aka positively charged hydrogen ions) in most otherwise empty space, along with the occasional normal atom or molecule.

[Chris Peterson]

In reference to my question regarding the transference and storage (absorption) of energy resulting from earthshine and moonshine, I neglected to include time as a variable. In addition, I'm not limiting my question to a parochial moon-earth thing. The question I've in mind is how much energy is exchanged and stored among celestial bodies, seemingly in a passive format, yet collectively of possible consequence, in the search for dark energy.

Well, probably 99.999% of all light emitted by stars is not absorbed by anything, near or far. But that thought makes me wonder how much energy in the form of protons and neutrinos is free flying throughout the universe. I'll take that number in watts/m³ please, Chris. (is that even the correct unit?) :ssmile:

Watts per square meter would be a typical unit for irradiance. If you want to work with time and energy, you can consider the fact that a watt is one joule per second.

[DL MARTIN]

Is there not transference and absorption of light energy among galaxies? Or when I look at a star!

[Chris Peterson]

Is there not transference and absorption of light energy among galaxies? Or when I look at a star!

Energy is transferred by photons. It is always moving outward from sources like stars, and a tiny, tiny fraction will naturally get absorbed by atoms in distant places. But the energy a galaxy absorbs from the surrounding universe is such an immensely tiny fraction of the energy it generates locally that this absorbed energy has no meaningful physical effect.

Dark energy has no relationship to this.

[DL MARTIN]

Thanks to Chris Peterson and johnnydeep for your patience in clarifying things.

[johnnydeep]

In reference to my question regarding the transference and storage (absorption) of energy resulting from earthshine and moonshine, I neglected to include time as a variable. In addition, I'm not limiting my question to a parochial moon-earth thing. The question I've in mind is how much energy is exchanged and stored among celestial bodies, seemingly in a passive format, yet collectively of possible consequence, in the search for dark energy.

Well, probably 99.999% of all light emitted by stars is not absorbed by anything, near or far. But that thought makes me wonder how much energy in the form of protons and neutrinos is free flying throughout the universe. I'll take that number in watts/m³ please, Chris. (is that even the correct unit?)

Watts per square meter would be a typical unit for irradiance. If you want to work with time and energy, you can consider the fact that a watt is one joule per second.

Ok, so then (...after reading wikipedia...), I guess that energy density is what I was after, which is Joules/m³, and therefore also Watt seconds/m³, which tortured unit probably is helpful to no one.

[Chris Peterson]

Well, probably 99.999% of all light emitted by stars is not absorbed by anything, near or far. But that thought makes me wonder how much energy in the form of protons and neutrinos is free flying throughout the universe. I'll take that number in watts/m³ please, Chris. (is that even the correct unit?) :ssmile:

Watts per square meter would be a typical unit for irradiance. If you want to work with time and energy, you can consider the fact that a watt is one joule per second.

Ok, so then (...after reading wikipedia...), I guess that energy density is what I was after, which is Joules/m³, and therefore also Watt seconds/m³, which tortured unit probably is helpful to no one.

There are about a dozen ways of looking at luminance and flux and energy density and spectral irradiance and...

Many have tortured units, and keeping track of the sometimes subtle differences between them can be a challenge.

[Ann]

I was supposed to be there and see the eclipse, which would have been my first ever. But... then we got the pandemic, and we cancelled.

Ann

[sillyworm 2]

Gorgeous

[Chris Peterson]

I was supposed to be there and see the eclipse, which would have been my first ever. But... then we got the pandemic, and we cancelled

Well, that's a bummer! It's an experience that has no equal.

But you've got some good opportunities in the near future. A very good one in the U.S. in 2024 (if the U.S. is still here; stop by Colorado for a visit). 2026 in Spain, 2027 Spain and Northern Africa.

[Wolf]

Am I just having a pareidolia or is this a black eye for January 7th.