APOD: Moon Setting Behind Teide Volcano (2023 Dec 03)

[APOD Robot]

Moon Setting Behind Teide Volcano

Explanation: These people are not in danger. What is coming down from the left is just the Moon, far in the distance. Luna appears so large here because she is being photographed through a telescopic lens. What is moving is mostly the Earth, whose spin causes the Moon to slowly disappear behind Mount Teide, a volcano in the Canary Islands off the northwest coast of Africa. The people pictured are 16 kilometers away and many are facing the camera because they are watching the Sun rise behind the photographer. It is not a coincidence that a full moon rises just when the Sun sets because the Sun is always on the opposite side of the sky from a full moon. The featured video was made in 2018 during the full Milk Moon. The video is not time-lapse -- this was really how fast the Moon was setting.

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[Confused]

Is there a fire on the peak? There appears to be smoke rising from it. I do not however see the smoke when the Moon is not behind the peak, therefore it is probably an illusion.

[johnnydeep]

Is there a fire on the peak? There appears to be smoke rising from it. I do not however see the smoke when the Moon is not behind the peak, therefore it is probably an illusion.

Almost certainly no fire, but it conceivably might have been smoke rising from the volcano, assuming it's even active. But in this case I do think the "smoke" is just an optical effect of some kind.

[Chris Peterson]

Is there a fire on the peak? There appears to be smoke rising from it. I do not however see the smoke when the Moon is not behind the peak, therefore it is probably an illusion.

Almost certainly no fire, but it conceivably might have been smoke rising from the volcano, assuming it's even active. But in this case I do think the "smoke" is just an optical effect of some kind.

We're looking horizontally through 16 km of air! I'm amazed we don't see more thermal effects.

[johnnydeep]

Is there a fire on the peak? There appears to be smoke rising from it. I do not however see the smoke when the Moon is not behind the peak, therefore it is probably an illusion.

Almost certainly no fire, but it conceivably might have been smoke rising from the volcano, assuming it's even active. But in this case I do think the "smoke" is just an optical effect of some kind.

We're looking horizontally through 16 km of air! I'm amazed we don't see more thermal effects.

True!

[johnnydeep]

Almost certainly no fire, but it conceivably might have been smoke rising from the volcano, assuming it's even active. But in this case I do think the "smoke" is just an optical effect of some kind.

We're looking horizontally through 16 km of air! I'm amazed we don't see more thermal effects.

True!

Is occurred to me that the distance from the camera to the people on the volcano is 16 km, but there's also a few more km of atmosphere that the light from the moon would have to go through before reaching those people!

[Chris Peterson]

We're looking horizontally through 16 km of air! I'm amazed we don't see more thermal effects.

True!

Is occurred to me that the distance from the camera to the people on the volcano is 16 km, but there's also a few more km of atmosphere that the light from the moon would have to go through before reaching those people!

True... but they're at 12,000 feet or so, so most of the continuing path is largely above the strongest atmospheric effects, and mainly just blurs out lunar features a little. Probably most of the visible, convective motion we're seeing is quite close to the camera.

[johnnydeep]

True!

Is occurred to me that the distance from the camera to the people on the volcano is 16 km, but there's also a few more km of atmosphere that the light from the moon would have to go through before reaching those people!

True... but they're at 12,000 feet or so, so most of the continuing path is largely above the strongest atmospheric effects, and mainly just blurs out lunar features a little. Probably most of the visible, convective motion we're seeing is quite close to the camera.

Thanks. And I presume any atmospheric thermal effects would also be minimal in the more typical case of a telescope pointed at the moon much more vertically.

[Chris Peterson]

Is occurred to me that the distance from the camera to the people on the volcano is 16 km, but there's also a few more km of atmosphere that the light from the moon would have to go through before reaching those people!

True... but they're at 12,000 feet or so, so most of the continuing path is largely above the strongest atmospheric effects, and mainly just blurs out lunar features a little. Probably most of the visible, convective motion we're seeing is quite close to the camera.

Thanks. And I presume any atmospheric thermal effects would also be minimal in the more typical case of a telescope pointed at the moon much more vertically.

Seeing issues tend to involve ground effects in the few tens of meters close to the ground, and the effects of high altitude winds at thousands of meters. The latter is what makes stars twinkle and creates local distortion on the Moon here, but it just looks like random wiggling. The ground effects result from mostly rising air, so we see a different kind of structure if we're looking horizontally through it.

[johnnydeep]

True... but they're at 12,000 feet or so, so most of the continuing path is largely above the strongest atmospheric effects, and mainly just blurs out lunar features a little. Probably most of the visible, convective motion we're seeing is quite close to the camera.

Thanks. And I presume any atmospheric thermal effects would also be minimal in the more typical case of a telescope pointed at the moon much more vertically.

Seeing issues tend to involve ground effects in the few tens of meters close to the ground, and the effects of high altitude winds at thousands of meters. The latter is what makes stars twinkle and creates local distortion on the Moon here, but it just looks like random wiggling. The ground effects result from mostly rising air, so we see a different kind of structure if we're looking horizontally through it.

Ah - got it.

[Confused]

Is occurred to me that the distance from the camera to the people on the volcano is 16 km, but there's also a few more km of atmosphere that the light from the moon would have to go through before reaching those people!

Except whatever it is that I see, it is only near the land and only rising from the land, in the direction opposing the perceived direction of movement of the Moon. Twice in the video I see flashes of light, one at the very end of the video. If it is real smoke it is strange we do not see it when the Moon is not behind it.

[Chris Peterson]

Is occurred to me that the distance from the camera to the people on the volcano is 16 km, but there's also a few more km of atmosphere that the light from the moon would have to go through before reaching those people!

Except whatever it is that I see, it is only near the land and only rising from the land, in the direction opposing the perceived direction of movement of the Moon. Twice in the video I see flashes of light, one at the very end of the video. If it is real smoke it is strange we do not see it when the Moon is not behind it.

I don't think there is any smoke.

[johnnydeep]

Is occurred to me that the distance from the camera to the people on the volcano is 16 km, but there's also a few more km of atmosphere that the light from the moon would have to go through before reaching those people!

Except whatever it is that I see, it is only near the land and only rising from the land, in the direction opposing the perceived direction of movement of the Moon. Twice in the video I see flashes of light, one at the very end of the video. If it is real smoke it is strange we do not see it when the Moon is not behind it.

I don't think there is any smoke.

I do see the flashes of light, all from the same area - which also happens to have a bunch of people. Not sure what it is. Here's a flash near the end:

[Chris Peterson]

Except whatever it is that I see, it is only near the land and only rising from the land, in the direction opposing the perceived direction of movement of the Moon. Twice in the video I see flashes of light, one at the very end of the video. If it is real smoke it is strange we do not see it when the Moon is not behind it.

I don't think there is any smoke.

I do see the flashes of light, all from the same area - which also happens to have a bunch of people. Not sure what it is. Here's a flash near the end:


fire on the mountain.png

Since those people are watching the Sun come up behind the camera, it's hardly surprising that we'd see bright reflections off their cameras or other things they have with them.

[johnnydeep]

I don't think there is any smoke.

I do see the flashes of light, all from the same area - which also happens to have a bunch of people. Not sure what it is. Here's a flash near the end:


fire on the mountain.png

Since those people are watching the Sun come up behind the camera, it's hardly surprising that we'd see bright reflections off their cameras or other things they have with them.

Thanks. Funny how there's a very reasonable explanation for almost everything!

[pferkul]

Very good!

Here's a version with different background music, the conclusion to Beethoven's Moonlight Sonata:

Click to play embedded YouTube video.

[Daveman1]

Am I missing something? Shouldn't "It is not a coincidence that a full moon rises just when the Sun sets" be the other way around? We are watching the moon set behind people who are watching the sun rise, aren't we?

[Chris Peterson]

Am I missing something? Shouldn't "It is not a coincidence that a full moon rises just when the Sun sets" be the other way around? We are watching the moon set behind people who are watching the sun rise, aren't we?

Of course, the statement is correct either way. But yes... in the context of what's happening here, it would read better the other way.

[Daveman1]

Thanks Chris. Not complaining, just wanted to make sure I wasn't misunderstanding. I'm a big fan of these guys. I congratulated them on the 5th anniversary of APOD and one of them (can't remember which) wrote back. Nice!