APOD: Moon and Smoke Rings from Mt. Etna (2024 Apr 22)

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APOD: Moon and Smoke Rings from Mt. Etna (2024 Apr 22)

Post by APOD Robot » Mon Apr 22, 2024 4:08 am

Image Moon and Smoke Rings from Mt. Etna

Explanation: Yes, but can your volcano do this? To the surprise of some, Mt. Etna emits, on occasion, smoke rings. Technically known as vortex rings, the walls of the volcano slightly slow the outside of emitted smoke puffs, causing the inside gas to move faster. A circle of low pressure develops so that the emitted puff of volcanic gas and ash loops around in a ring, a familiar geometric structure that can be surprisingly stable as it rises. Smoke rings are quite rare and need a coincidence of the right geometry of the vent, the right speed of ejected smoke, and the relative calmness of the outside atmosphere. In the featured image taken about two weeks ago from Gangi, Sicily, Italy, multiple volcanic smoke rings are visible. The scene is shaded by the red light of a dawn Sun, while a crescent Moon is visible in the background.

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Ann
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Re: APOD: Moon and Smoke Rings from Mt. Etna (2024 Apr 22)

Post by Ann » Mon Apr 22, 2024 5:51 am

APOD 22 April 2024 cropped.png
Moon and Smoke Rings from Mt. Etna (cropped).
Image Credit & Copyright: Dario Giannobile


Great image! :D But I took the liberty of editing out Mt. Etna itself to bring out the otherworldliness of the almost organic and lifelike tendrils of smoke rising from Mt. Etna and "blooming into rings" at the top. The large-looking and very thin waning crescent Moon sure adds to the ethereal, dreamlike quality of the image.

Thanks to APOD Robot for providing a good explanation for the smoke rings:
Technically known as vortex rings, the walls of the volcano slightly slow the outside of emitted smoke puffs, causing the inside gas to move faster. A circle of low pressure develops so that the emitted puff of volcanic gas and ash loops around in a ring, a familiar geometric structure that can be surprisingly stable as it rises. Smoke rings are quite rare and need a coincidence of the right geometry of the vent, the right speed of ejected smoke, and the relative calmness of the outside atmosphere.

I started a thread about these smoke rings two weeks ago. I posted a video there which, however, you have to watch on Youtube, since it is not directly available at Starship Asterisk*. plasmaengine also posted a nice video there.

Ann
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Re: APOD: Moon and Smoke Rings from Mt. Etna (2024 Apr 22)

Post by JohnD » Mon Apr 22, 2024 10:06 am

That looks even more like the back drop for some SF movie!
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Re: APOD: Moon and Smoke Rings from Mt. Etna (2024 Apr 22)

Post by johnnydeep » Mon Apr 22, 2024 12:27 pm

Wow, that Youtube link is impressive and many of the closeups of the rings could easily be mistaken by those who "want to believe" of being UFOs/UAPs!

Click to play embedded YouTube video.
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"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}

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Re: APOD: Moon and Smoke Rings from Mt. Etna (2024 Apr 22)

Post by Bartolo » Mon Apr 22, 2024 1:54 pm

How wide are Mt Etna's smoke rings?

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Re: APOD: Moon and Smoke Rings from Mt. Etna (2024 Apr 22)

Post by wilddouglascounty » Mon Apr 22, 2024 3:15 pm

If it was around 2 weeks ago in the morning, that waning crescent was heading toward a solar eclipse!

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Re: APOD: Moon and Smoke Rings from Mt. Etna (2024 Apr 22)

Post by Chris Peterson » Mon Apr 22, 2024 3:26 pm

Bartolo wrote: Mon Apr 22, 2024 1:54 pm How wide are Mt Etna's smoke rings?
Well, the image was made about 70km from Etna, so given the Moon is a half degree wide, the smoke rings are about 0.08 degrees, and must therefore be about 100 meters across.
Chris

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Re: APOD: Moon and Smoke Rings from Mt. Etna (2024 Apr 22)

Post by ChrisHeinz » Mon May 06, 2024 11:56 pm

Wow! Those look so much like jellyfish ?!?!?

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Re: APOD: Moon and Smoke Rings from Mt. Etna (2024 Apr 22)

Post by ChrisHeinz » Tue May 07, 2024 12:03 am

OMG!!! IT'S THE FSM!!! (Flying Spaghetti Monster!) Finally, a religion delivers!
https://en.wikipedia.org/wiki/Flying_Spaghetti_Monster

ChrisHeinz

Re: APOD: Moon and Smoke Rings from Mt. Etna (2024 Apr 22)

Post by ChrisHeinz » Tue May 07, 2024 12:08 am

Pastafarianism, FTW! ;->