APOD: A Volcano of Fire under a Milky Way... (2019 May 27)

Comments and questions about the APOD on the main view screen.
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APOD: A Volcano of Fire under a Milky Way... (2019 May 27)

Post by APOD Robot » Mon May 27, 2019 4:08 am

Image A Volcano of Fire under a Milky Way of Stars

Explanation: Sometimes it's hard to decide which is more impressive -- the land or the sky. On the land of the featured image, for example, the Volcano of Fire (Volcán de Fuego) is seen erupting topped by red-hot, wind-blown ash and with streams of glowing lava running down its side. Lights from neighboring towns are seen through a thin haze below. In the sky, though, the central plane of our Milky Way Galaxy runs diagonally from the upper left, with a fleeting meteor just below, and the trail of a satellite to the upper right. The planet Jupiter also appears toward the upper left, with the bright star Antares just to its right. Much of the land and the sky were captured together in a single, well-timed, 25-second exposure taken in mid-April from the side of Fuego's sister volcano Acatenango in Guatemala. The image of the meteor, though, was captured in a similar frame taken about 30 minutes earlier -- when the volanic eruption was not as photogenic -- and added later digitally.

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Re: APOD: A Volcano of Fire under a Milky Way... (2019 May 27)

Post by Ann » Mon May 27, 2019 4:42 am

What is the bright light at 10 o'clock? Surely not Saturn, current magnitude +0.3 (compared with -2.6 for Jupiter)?

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Re: APOD: A Volcano of Fire under a Milky Way... (2019 May 27)

Post by alter-ego » Mon May 27, 2019 5:24 am

Ann wrote:
Mon May 27, 2019 4:42 am
What is the bright light at 10 o'clock? Surely not Saturn, current magnitude +0.3 (compared with -2.6 for Jupiter)?
APOD Robot wrote:
Mon May 27, 2019 4:08 am
The planet Jupiter also appears toward the upper left, with the bright star just to its right. ... taken in mid-April ...
Neither the EXIF data or the APOD description make sense to me for what's imaged. Jupiter is very close to the imaged position on Feb 13, 2019, and on that date, the bright object corresponds exactly to Venus.
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Re: APOD: A Volcano of Fire under a Milky Way... (2019 May 27)

Post by NCTom » Mon May 27, 2019 10:10 am

My old eyes seem to have found three meteor streaks besides the satellite, and I have the same question as Ann.Three bright objects on the left of the photo, the brightest is farthest left, then second brightest with the least bright farthest right. Two planets and then Antares?

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Re: APOD: A Volcano of Fire under a Milky Way... (2019 May 27)

Post by orin stepanek » Mon May 27, 2019 10:42 am

I like the photo; lots of color; nicely done! :thumb_up: :thumb_up:
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Re: APOD: A Volcano of Fire under a Milky Way... (2019 May 27)

Post by Boomer12k » Mon May 27, 2019 11:23 am

Nice view...

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Re: APOD: A Volcano of Fire under a Milky Way... (2019 May 27)

Post by dddavids49 » Mon May 27, 2019 12:15 pm

What's the golden column of light to the left of the comet?

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Re: APOD: A Volcano of Fire under a Milky Way... (2019 May 27)

Post by alter-ego » Mon May 27, 2019 10:21 pm

dddavids49 wrote:
Mon May 27, 2019 12:15 pm
What's the golden column of light to the left of the comet?
Given how clear the sky appears, that is most likely a wind-blown plume from the volcano. It is front-lit from the population centers not directly visible, the largest of which is Guatemala City (pop. 1 million).
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Re: APOD: A Volcano of Fire under a Milky Way... (2019 May 27)

Post by MarkBour » Tue May 28, 2019 4:23 pm

Ann wrote:
Mon May 27, 2019 4:42 am
What is the bright light at 10 o'clock? Surely not Saturn, current magnitude +0.3 (compared with -2.6 for Jupiter)?

Ann
Well, I can see why you ask it that way ...

To go from From Volcan de Acatenango to Volcan de Fuego is a journey almost due south. This view, situated at approximately
14.42357356,-90.87312718
must have been taken while standing on the west side of the Volcan de Acatenango cone and looking almost due south, a little bit east.
https://earth.app.goo.gl/a2zsWA
Capture.JPG
With this info, if I set the Stellarium web
(https://stellarium-web.org/)
to these coordinates, looking SSE on 2019-04-15 at 03:00,
I get:

... so it seems to be in the right spot for Saturn !
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Re: APOD: A Volcano of Fire under a Milky Way... (2019 May 27)

Post by Ann » Tue May 28, 2019 4:27 pm

Thanks, Mark! I can see that Saturn grew awfully bright at least for a few hours one night in April this year! :wink:

Was the picture taken on April 14? Then Saturn must have turned on its fireworks to celebrate my brother, because it is his birthday on April 14! :D

Ohhh... the picture was taken on April 15. Darn it! You were one day late for my brother, Saturn!

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Re: APOD: A Volcano of Fire under a Milky Way... (2019 May 27)

Post by Astronymus » Tue May 28, 2019 5:37 pm

NCTom wrote:
Mon May 27, 2019 10:10 am
My old eyes seem to have found three meteor streaks besides the satellite, and I have the same question as Ann.Three bright objects on the left of the photo, the brightest is farthest left, then second brightest with the least bright farthest right. Two planets and then Antares?
I only see one meteor streak and three satellite trails.
» Oh, yeah. Oooh, ahhh, that's how it always starts. But then later there's running and... and screaming. «

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Re: APOD: A Volcano of Fire under a Milky Way... (2019 May 27)

Post by alter-ego » Wed May 29, 2019 4:48 am

MarkBour wrote:
Tue May 28, 2019 4:23 pm
Ann wrote:
Mon May 27, 2019 4:42 am
What is the bright light at 10 o'clock? Surely not Saturn, current magnitude +0.3 (compared with -2.6 for Jupiter)?

Ann
Well, I can see why you ask it that way ...

To go from From Volcan de Acatenango to Volcan de Fuego is a journey almost due south. This view, situated at approximately
14.42357356,-90.87312718
must have been taken while standing on the west side of the Volcan de Acatenango cone and looking almost due south, a little bit east.
https://earth.app.goo.gl/a2zsWA
Capture.JPG
With this info, if I set the Stellarium web
(https://stellarium-web.org/)
to these coordinates, looking SSE on 2019-04-15 at 03:00,
I get:

... so it seems to be in the right spot for Saturn !
You've got to look at the position of Jupiter carefully.
Your chart places Jupiter about 4° east of the imaged position. If you zoom in on the APOD you can see Jupiter lies roughly midway between mag 7.5 HIP 84491 and mag 7.9 HIP 84172. The only date possible for Jupiter to be at the image position is Feb 13, 11:00 UT ± <12 hours. Jupiter's J2000 RA = 258.6° ± 0.1°, J2000 Dec = -22.40° ± <0.05°.
In this case it is more important, and most accurate, to determine the planet's position wrt surrounding stars before positioning the observer. As I stated earlier, -4.4 mag Venus is exactly at the brightest object position, and, in fact, Saturn is located just below the rock outcropping nearest 37 Sgr. I invite you to identify the star fields. The 4° position in your chart will be pretty easy to identify. I could see it on your chart without any fainter magnitudes displayed.
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Re: APOD: A Volcano of Fire under a Milky Way... (2019 May 27)

Post by MarkBour » Wed May 29, 2019 10:24 pm

alter-ego wrote:
Wed May 29, 2019 4:48 am
You've got to look at the position of Jupiter carefully.
Your chart places Jupiter about 4° east of the imaged position. If you zoom in on the APOD you can see Jupiter lies roughly midway between mag 7.5 HIP 84491 and mag 7.9 HIP 84172. The only date possible for Jupiter to be at the image position is Feb 13, 11:00 UT ± <12 hours. Jupiter's J2000 RA = 258.6° ± 0.1°, J2000 Dec = -22.40° ± <0.05°.
In this case it is more important, and most accurate, to determine the planet's position wrt surrounding stars before positioning the observer. As I stated earlier, -4.4 mag Venus is exactly at the brightest object position, and, in fact, Saturn is located just below the rock outcropping nearest 37 Sgr. I invite you to identify the star fields. The 4° position in your chart will be pretty easy to identify. I could see it on your chart without any fainter magnitudes displayed.
Ah. Your comment came back with more force this time!
So you can rule out the statement in the APOD caption of "...taken in mid-April", whereas the first time you seemed not so certain.
This is a very nice example -- thanks for explaining how to work it out!
Mark Goldfain

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Re: APOD: A Volcano of Fire under a Milky Way... (2019 May 27)

Post by Jim Armstrong » Wed May 29, 2019 10:26 pm

[float=][/float]My first thought a few days ago was the same as alter-ego's: what is the golden column that dominates the left half of the Picture?
I figured someone would give a satisfactory answer, but I still don't know.
I hope it is not too late to find out.
Shouldn't have to redo the qualifying question after preview. Doesn't always work anyway.

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Re: APOD: A Volcano of Fire under a Milky Way... (2019 May 27)

Post by MarkBour » Wed May 29, 2019 11:10 pm

alter-ego wrote:
Wed May 29, 2019 4:48 am
You've got to look at the position of Jupiter carefully.
Your chart places Jupiter about 4° east of the imaged position. If you zoom in on the APOD you can see Jupiter lies roughly midway between mag 7.5 HIP 84491 and mag 7.9 HIP 84172. The only date possible for Jupiter to be at the image position is Feb 13, 11:00 UT ± <12 hours. Jupiter's J2000 RA = 258.6° ± 0.1°, J2000 Dec = -22.40° ± <0.05°.
In this case it is more important, and most accurate, to determine the planet's position wrt surrounding stars before positioning the observer. As I stated earlier, -4.4 mag Venus is exactly at the brightest object position, and, in fact, Saturn is located just below the rock outcropping nearest 37 Sgr. I invite you to identify the star fields. The 4° position in your chart will be pretty easy to identify. I could see it on your chart without any fainter magnitudes displayed.
Incidentally, if I put Stellarium to Feb 19, it looks like Venus and Saturn are in conjunction. Actually much better on Feb 18, but on Feb 19 close enough for me to think that both would be in view. Of course, as Saturn is so faint, it might be impossible to see on Feb 18, and might just be one of the dots of light near Venus on Feb 19. I guess Saturn should be brighter than Antares, though.

I note that you gave me an assignment in your comment, perhaps a simple student's assignment. But I confess I'm a bit lost as to how to identify a star field in an image of the Milky way. I tend to just start from ignorance and take the APOD caption at its word ("okay, they said that one was Antares") and go from there. I'm not sure how to go from a very rich image with a million dots in it to pick out which is which. Perhaps this comes from a bit of study of the Milky Way, to get some landmarks? (Would "skymarks" be a better word for that?)
Mark Goldfain

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Re: APOD: A Volcano of Fire under a Milky Way... (2019 May 27)

Post by neufer » Wed May 29, 2019 11:14 pm

alter-ego wrote:
Mon May 27, 2019 10:21 pm
dddavids49 wrote:
Mon May 27, 2019 12:15 pm

What's the golden column of light to the left of the comet?
Given how clear the sky appears, that is most likely a wind-blown plume from the volcano.

It is front-lit from the population centers not directly visible, the largest of which is Guatemala City (pop. 1 million).
Seems reasonable.
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Re: APOD: A Volcano of Fire under a Milky Way... (2019 May 27)

Post by Chris Peterson » Wed May 29, 2019 11:16 pm

Jim Armstrong wrote:
Wed May 29, 2019 10:26 pm
[float=][/float]My first thought a few days ago was the same as alter-ego's: what is the golden column that dominates the left half of the Picture?
I figured someone would give a satisfactory answer, but I still don't know.
I hope it is not too late to find out.
Shouldn't have to redo the qualifying question after preview. Doesn't always work anyway.
A bit of drifting cloud or smoke illuminated by the artificial lights on the ground.
Chris

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Re: APOD: A Volcano of Fire under a Milky Way... (2019 May 27)

Post by alter-ego » Sat Jun 01, 2019 7:53 pm

MarkBour wrote:
Wed May 29, 2019 11:10 pm
...
I note that you gave me an assignment in your comment, perhaps a simple student's assignment. But I confess I'm a bit lost as to how to identify a star field in an image of the Milky way. I tend to just start from ignorance and take the APOD caption at its word ("okay, they said that one was Antares") and go from there. I'm not sure how to go from a very rich image with a million dots in it to pick out which is which. Perhaps this comes from a bit of study of the Milky Way, to get some landmarks? (Would "skymarks" be a better word for that?)
Hi Mark - Yeah, I just thought you might be interested to look deeper so I wanted to nudge you to do so. I knew I added detail that wouldn't be easy to jump into, but was by no means intended as a talking-down-to. I apologize if I came across that way. I just wanted to remove all speculation, "put the last nail in the coffin so to speak.

Regarding "skymarks", or signposts, in this image, finding familiar star asterisms is difficult because of the quantity of stars and how they appear. The apparent relative star brightnesses are compressed so much that it's hard to see familiar constellations and identify stars. However, I did immediately recognize some Milky Way dark nebula and dust lanes. With these structures identified, I could then look and smaller regions and identify stars (Hint: In Stellarium, you can similarly compress relative star brightness to simulate quite well the star density and appearance in this image). The Pipe Nebula is one familiar nebula. Interestingly, I've known it, but I just learned that the Pipe Nebula is the butt and hind leg(s) of the Dark Horse Nebula. In the APOD, Jupiter is positioned very near the hoof of the bent front leg. From here, identifying surrounding stars is straight forward as you can focus on that region. That is how I located Jupiter, and the image exposure date. Oh, further refinement of the time is possible by accounting for photographer's location. I only cared about the day, not the exact time.
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Re: APOD: A Volcano of Fire under a Milky Way... (2019 May 27)

Post by MarkBour » Mon Jun 03, 2019 10:50 pm

Ann wrote:
Mon May 27, 2019 4:42 am
What is the bright light at 10 o'clock? Surely not Saturn, current magnitude +0.3 (compared with -2.6 for Jupiter)?

Ann
dddavids49 wrote:
Mon May 27, 2019 12:15 pm
What's the golden column of light to the left of the comet?
Here's confirmation of alter-ego's deduction and alter-ego's and Chris Peterson's answers.
From Diego Rizzo on facebook --
Capture.JPG
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