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Posted: **Mon May 13, 2024 4:06 am**

AR 3664 on a Setting Sun

Explanation: It was larger than the Earth. It was so big you could actually see it on the Sun's surface without magnification. It contained powerful and tangled magnetic fields as well as numerous dark sunspots. Labelled AR 3664, it developed into one of the most energetic areas seen on the Sun in recent years, unleashing a series of explosions that led to a surge of energetic particles striking the Earth, which created beautiful auroras. And might continue. Although active regions on the Sun like AR 3664 can be quite dangerous, this region's Coronal Mass Ejections have not done, as yet, much damage to Earth-orbiting satellites or Earth-surface electrical grids. Pictured, the enormous active region was captured on the setting Sun a few days ago from Civitavecchia, Rome, Italy. The composite image includes a very short exposure taken of just the Sun's surface, but mimics what was actually visible. Finally, AR 3664 is now rotating away from the Earth, although the region may survive long enough to come around again.

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Posted: **Mon May 13, 2024 8:10 am**

So is it 3664 or 6443?

Posted: **Mon May 13, 2024 1:44 pm**

Rauf wrote: ↑Mon May 13, 2024 8:10 am So is it 3664 or 6443?

AR 3664.

Posted: **Mon May 13, 2024 6:18 pm**

Chris Peterson wrote: ↑Mon May 13, 2024 1:44 pm
Rauf wrote: ↑Mon May 13, 2024 8:10 am So is it 3664 or 6443?
AR 3664.

Yeah, I see it's now fixed

Posted: **Mon May 13, 2024 7:25 pm**

We are getting alot of photoshopped pictures .
What do I mean? In this case, a picture of the sunspots superimposed on the sun in a photo in which the sun would be too bright to look at, to cause an artistic view. Photo or portrait?

Posted: **Mon May 13, 2024 7:34 pm**

Rou wrote: ↑Mon May 13, 2024 7:25 pm We are getting alot of photoshopped pictures .
What do I mean? In this case, a picture of the sunspots superimposed on the sun in a photo in which the sun would be too bright to look at, to cause an artistic view. Photo or portrait?

It's an HDR image, composited from several different exposure times to extend the dynamic range and come closer to what the eye would see here. It's entirely likely that a Sun only 2° above the horizon could be viewed with the naked eye and sunspots seen on it.

Posted: **Mon May 13, 2024 7:49 pm**

Hi! I'd like to introduce myself, I'm Lee! I won't be contributing anything of value to these discussions. I just love to look at the pictures. As an example, the first thing I thought of when I saw this one was "ET phone home". So, there ya go! I do read the discussions and sometimes even understand some.

Posted: **Mon May 13, 2024 8:37 pm**

Lee wrote: ↑Mon May 13, 2024 7:49 pm Hi! I'd like to introduce myself, I'm Lee! I won't be contributing anything of value to these discussions. I just love to look at the pictures. As an example, the first thing I thought of when I saw this one was "ET phone home". So, there ya go! I do read the discussions and sometimes even understand some.

Different celestial body, but there's a definite resemblance:

And this one with a real biker:

And finally, welcome!

Posted: **Mon May 13, 2024 8:55 pm**

Hopefully someone can clear up some sun confusions for me.

Today's APOD shows AR-3664 towards the BOTTOM of the solar disk. That of May 11 showed this cluster to be towards the RIGHT.

Does the apparent orientation of the sun shift from day to day?

My understanding is that the storms move from left to right basically parallel to the solar equator? So why the above difference in location between the images—was the telescope simply rotated?

Also, expect this to be a another gobsmacking question for anyone who knows anything about astronomy (which is *not* me), but I do know from personal observation that when viewed from the southern hemisphere the moon appears both left/right and top/bottom reversed compared to how it appears in the northern hemisphere: Is the same true of the Sun?

Thanks

Posted: **Mon May 13, 2024 10:09 pm**

WonderingLaddie wrote: ↑Mon May 13, 2024 8:55 pm Hopefully someone can clear up some sun confusions for me.

Today's APOD shows AR-3664 towards the BOTTOM of the solar disk. That of May 11 showed this cluster to be towards the RIGHT.

Does the apparent orientation of the sun shift from day to day?

My understanding is that the storms move from left to right basically parallel to the solar equator? So why the above difference in location between the images—was the telescope simply rotated?

Also, expect this to be a another gobsmacking question for anyone who knows anything about astronomy (which is *not* me), but I do know from personal observation that when viewed from the southern hemisphere the moon appears both left/right and top/bottom reversed compared to how it appears in the northern hemisphere: Is the same true of the Sun?

Thanks

The apparent disk of the Sun rotates by about 180° between sunrise and sunset (with respect to the horizon). Consider that when you're watching the Sun rise in the east, its north pole is pointing to the left. At sunset, it is pointing to the right. So a camera that is oriented so that its lower edge is parallel to whatever horizon is in front of it will see the Sun at a varying angle as it crosses the sky. This is very obvious with the Moon since we can easily observe fixed features over the course of a night without any need for filters.

Posted: **Tue May 14, 2024 3:16 am**

Well, at first I also had the same question. Thanks for the explanation. I'm a newbie so I took pictures like that but most of them weren't that clear.

A nice picture.

Posted: **Tue May 14, 2024 4:01 am**

It's a matter of geometric perspective.

Posted: **Tue May 14, 2024 6:14 am**

As much as we do not question the educational value of studying solar activity, this image leaves me very puzzled. I believe that it is not a correct representation of reality even if made according to an HDR technique.

For one thing, the Sun is not aligned with the brightest part of the reflection on the sea, which seems to have been taken when the Sun was higher and further to the left.

Also, it is possible to see how the image is a photomontage by looking at the lower right branch at the point where it touches the horizon. A step on the sea horizon is visible at that position.

Another doubt arises from the fact that the sea horizon disappears to the right among the bushes and is no longer visible.

I checked the forum for other work by this author and found that he is responsible for a fake APOD image for which he has been much criticized by the astrophotography community. You can read the discussion on this same forum at the following address:viewtopic.php?t=37389

Posted: **Tue May 14, 2024 5:47 pm**

Chris Peterson wrote: ↑Mon May 13, 2024 10:09 pm
WonderingLaddie wrote: ↑Mon May 13, 2024 8:55 pm Hopefully someone can clear up some sun confusions for me.

Today's APOD shows AR-3664 towards the BOTTOM of the solar disk. That of May 11 showed this cluster to be towards the RIGHT.

Does the apparent orientation of the sun shift from day to day?

My understanding is that the storms move from left to right basically parallel to the solar equator? So why the above difference in location between the images—was the telescope simply rotated?

Also, expect this to be a another gobsmacking question for anyone who knows anything about astronomy (which is *not* me), but I do know from personal observation that when viewed from the southern hemisphere the moon appears both left/right and top/bottom reversed compared to how it appears in the northern hemisphere: Is the same true of the Sun?

Thanks
The apparent disk of the Sun rotates by about 180° between sunrise and sunset (with respect to the horizon). Consider that when you're watching the Sun rise in the east, its north pole is pointing to the left. At sunset, it is pointing to the right. So a camera that is oriented so that its lower edge is parallel to whatever horizon is in front of it will see the Sun at a varying angle as it crosses the sky. This is very obvious with the Moon since we can easily observe fixed features over the course of a night without any need for filters.

Man, I will never be able to visualize 3D motions correctly. A full 180° rotation is very hard to believe (but I believe you anyway). Is that rotation on the Sun's spin axis, or clockwise or counterclockwise from our sight line perspective? This diagram from Wikipedia doesn't help me much either, though it clearly should:

: Click to view full size image

Posted: **Tue May 14, 2024 5:57 pm**

johnnydeep wrote: ↑Tue May 14, 2024 5:47 pm
Chris Peterson wrote: ↑Mon May 13, 2024 10:09 pm
WonderingLaddie wrote: ↑Mon May 13, 2024 8:55 pm Hopefully someone can clear up some sun confusions for me.

Today's APOD shows AR-3664 towards the BOTTOM of the solar disk. That of May 11 showed this cluster to be towards the RIGHT.

Does the apparent orientation of the sun shift from day to day?

My understanding is that the storms move from left to right basically parallel to the solar equator? So why the above difference in location between the images—was the telescope simply rotated?

Also, expect this to be a another gobsmacking question for anyone who knows anything about astronomy (which is *not* me), but I do know from personal observation that when viewed from the southern hemisphere the moon appears both left/right and top/bottom reversed compared to how it appears in the northern hemisphere: Is the same true of the Sun?

Thanks
The apparent disk of the Sun rotates by about 180° between sunrise and sunset (with respect to the horizon). Consider that when you're watching the Sun rise in the east, its north pole is pointing to the left. At sunset, it is pointing to the right. So a camera that is oriented so that its lower edge is parallel to whatever horizon is in front of it will see the Sun at a varying angle as it crosses the sky. This is very obvious with the Moon since we can easily observe fixed features over the course of a night without any need for filters.
Man, I will never be able to visualize 3D motions correctly. A full 180° rotation is very hard to believe (but I believe you anyway). Is that rotation on the Sun's spin axis, or clockwise or counterclockwise from our sight line perspective? This diagram from Wikipedia doesn't help me much either, though it clearly should:

Click to view full size image

Let's just look at the simplest test case, the motion of the Sun on an equinox, viewed from the equator. You agree that the Sun rises due east, crosses the zenith at noon, and sets due west, right? So facing east at sunrise, you would see the north pole of the Moon on its left side (pointing north). If you follow the Sun all day, keeping your left side pointing north (so rubber necking in a major way, or maybe lying on a tilt table... and this is what an equatorial telescope mount does) the Sun's orientation will not appear to change. Of course, you'll be standing on your head at sunset! But if you face the Sun at sunset (standing on your feet), north is now on your right. So the Sun's north pole will be on its right side. Its orientation has only changed with respect to the horizon. It's not really about 3D motion at all.

Posted: **Tue May 14, 2024 9:23 pm**

Chris Peterson wrote: ↑Tue May 14, 2024 5:57 pm
johnnydeep wrote: ↑Tue May 14, 2024 5:47 pm
Chris Peterson wrote: ↑Mon May 13, 2024 10:09 pm
The apparent disk of the Sun rotates by about 180° between sunrise and sunset (with respect to the horizon). Consider that when you're watching the Sun rise in the east, its north pole is pointing to the left. At sunset, it is pointing to the right. So a camera that is oriented so that its lower edge is parallel to whatever horizon is in front of it will see the Sun at a varying angle as it crosses the sky. This is very obvious with the Moon since we can easily observe fixed features over the course of a night without any need for filters.
Man, I will never be able to visualize 3D motions correctly. A full 180° rotation is very hard to believe (but I believe you anyway). Is that rotation on the Sun's spin axis, or clockwise or counterclockwise from our sight line perspective? This diagram from Wikipedia doesn't help me much either, though it clearly should:

Click to view full size image

Let's just look at the simplest test case, the motion of the Sun on an equinox, viewed from the equator. You agree that the Sun rises due east, crosses the zenith at noon, and sets due west, right? So facing east at sunrise, you would see the north pole of the Moon on its left side (pointing north). If you follow the Sun all day, keeping your left side pointing north (so rubber necking in a major way, or maybe lying on a tilt table... and this is what an equatorial telescope mount does) the Sun's orientation will not appear to change. Of course, you'll be standing on your head at sunset! But if you face the Sun at sunset (standing on your feet), north is now on your right. So the Sun's north pole will be on its right side. Its orientation has only changed with respect to the horizon. It's not really about 3D motion at all.

Thanks. That helps! I keep defaulting to looking at these motions from afar ("God's eye view") instead of what I'll actually experience when standing in place perpendicularly on the surface of the Earth while celestial bodies revolve and rotate all around me (or under my feet!). This must be why I never got into astrophotography in the slightest.

Posted: **Wed May 15, 2024 11:26 am**

Chris Peterson wrote: ↑Mon May 13, 2024 10:09 pm
WonderingLaddie wrote: ↑Mon May 13, 2024 8:55 pm Hopefully someone can clear up some sun confusions for me...

...My understanding is that the storms move from left to right basically parallel to the solar equator? So why the above difference in location between the images—was the telescope simply rotated?

Also, expect this to be a another gobsmacking question for anyone who knows anything about astronomy (which is *not* me), but I do know from personal observation that when viewed from the southern hemisphere the moon appears both left/right and top/bottom reversed compared to how it appears in the northern hemisphere: Is the same true of the Sun?

Thanks
The apparent disk of the Sun rotates by about 180° between sunrise and sunset (with respect to the horizon). Consider that when you're watching the Sun rise in the east, its north pole is pointing to the left. At sunset, it is pointing to the right. So a camera that is oriented so that its lower edge is parallel to whatever horizon is in front of it will see the Sun at a varying angle as it crosses the sky. This is very obvious with the Moon since we can easily observe fixed features over the course of a night without any need for filters.

Thanks so much! Did not know that we look at the sun from that orientation.

What about the view from northern/southern hemispheres? At any given moment is the view of the sun reversed as is that of the constellations and the moon?

Posted: **Wed May 15, 2024 3:14 pm**

Apologise if this somehow is a Gigantic Post--not clear to me how to respond to an individual post.

It was dispiriting to follow up the link given by Astro Mark (in the discussion of this APOD) to a previous APOD which I had much enjoyed and which is asserted to be a montage which, in my perspective of what an APOD is, would be a fake if not explicitly explained what had been done.

As far as this APOD, out of curiosity I ran it through a site which estimates the probability that an image is human-vs-AI generated. The site gave this one a probability of 85% for being a human photograph--the converse 15% probability of being AI generated (which Astro Mark did NOT suggest) would, I think, be consistent with digital manipulation of the sort suggested.

Link to that site: https://isitai.com/ai-image-detector/

Astro_mark wrote: ↑Tue May 14, 2024 6:14 am As much as we do not question the educational value of studying solar activity, this image leaves me very puzzled. I believe that it is not a correct representation of reality even if made according to an HDR technique.

For one thing, the Sun is not aligned with the brightest part of the reflection on the sea, which seems to have been taken when the Sun was higher and further to the left.

Also, it is possible to see how the image is a photomontage by looking at the lower right branch at the point where it touches the horizon. A step on the sea horizon is visible at that position.

Another doubt arises from the fact that the sea horizon disappears to the right among the bushes and is no longer visible.

I checked the forum for other work by this author and found that he is responsible for a fake APOD image for which he has been much criticized by the astrophotography community. You can read the discussion on this same forum at the following address:viewtopic.php?t=37389

...

Starship Asterisk*

APOD: AR 3664 on a Setting Sun (2024 May 13)

APOD: AR 3664 on a Setting Sun (2024 May 13)

Re: APOD: AR 3664 on a Setting Sun (2024 May 13)

Re: APOD: AR 3664 on a Setting Sun (2024 May 13)

Re: APOD: AR 3664 on a Setting Sun (2024 May 13)

Re: APOD: AR 3664 on a Setting Sun (2024 May 13)

Re: APOD: AR 3664 on a Setting Sun (2024 May 13)

Re: APOD: AR 3664 on a Setting Sun (2024 May 13)

Re: APOD: AR 3664 on a Setting Sun (2024 May 13)

Re: APOD: AR 3664 on a Setting Sun (2024 May 13)

Re: APOD: AR 3664 on a Setting Sun (2024 May 13)

Re: APOD: AR 3664 on a Setting Sun (2024 May 13)

Re: APOD: AR 3664 on a Setting Sun (2024 May 13)

Re: APOD: AR 3664 on a Setting Sun (2024 May 13)

Re: APOD: AR 3664 on a Setting Sun (2024 May 13)

Re: APOD: AR 3664 on a Setting Sun (2024 May 13)

Re: APOD: AR 3664 on a Setting Sun (2024 May 13)

Re: APOD: AR 3664 on a Setting Sun (2024 May 13)

Re: APOD: AR 3664 on a Setting Sun (2024 May 13)