Starship Asterisk*

by **sallyseaver** » Wed Mar 22, 2017 8:42 pm

canopia wrote:Thanks Ann! Actually that faint looking dot is indeed Mercury. It was at mag. -0.2 back then; I had to shoot it with the intervening clouds and the twilight had already begun. The brighter light above Mercury is the Moon, which was a thin crescent with earthshine.

Tunç Tezel
http://www.twanight.org

Thank you Tunç Tezel for this fabulous annotated image. How wonderful to be able to see the constellations this way as well as the planets. I have wanted a picture like this for a while; although, I'm not sure I could have articulated my desire as well as you fulfilled it.

Thank you, thank you!!

Most sincerely,
Sally

by **sallyseaver** » Wed Mar 22, 2017 8:34 pm

Ann wrote:Great image! It's fun to see the sky between two horizons, the eastern morning one at left and the western evening one at right.

Thanks a lot for the annotation! I would never have found Uranus, let alone Neptune, without it.

The labeling of Mercury is slightly confusing, though. Immediately to the upper left of the "M" in Mercury is a faint pinpoint of light, and I found myself wondering if that was Mercury. Much further from the "Mercury" lettering is a much brighter light, which would seem to be a much better match for the brightness I expect from Mercury.

Currently Mercury is magnitude −0.9, which makes it brighter than any star in the sky except Sirius. So I guess it is the bright light some distance away from the Mercury lettering that is the real Mercury.

Ann

Thank you Ann for getting this clarification from Tunç Tezel. I had the same question.

by **BDanielMayfield** » Mon Mar 06, 2017 4:42 pm

Atabakzadeh wrote:Oh, yeah, OK. You're really right. I do apologize.
I forgot the rotation of the earth. So even if you fix your camera on tripod, you can take almost 180° panorama from sky, at night, without rotating your camera.
And this amazing picture is an almost 350-360° panorama (except the sun itself). Yes, it's true.

I'm so ashamed.
But I want to be a great astronomer. Can I?

You could become a good astronomer, perhaps. You have learned to let go of a firmly held conviction when evidence called for adjusting your understanding. This was good for you Atabakzadeh, even though it was embarrassing. Even some once leading astronomers have found it so hard to let go of a wrong idea that their "greatness" has been tarnished. Being overly confident of the rightness of one's own understanding can block us off in the quest for truth.

"Knowledge puffs up,
love builds up."

Bruce

by **Ann** » Mon Mar 06, 2017 6:45 am

Atabakzadeh wrote:
Chris Peterson wrote:
Atabakzadeh wrote: and this panorama is 180°
I'm RIGHT.
No, you're not. You're not understanding how the image was made. It's a mosaic made between sunset and sunrise, as the sky was moving. It is possible with such an image to capture all of the ecliptic except about 20° on either side of the Sun, which will be too bright. Compare the image with any decent star map and you'll see that it covers a bit under 300° of starry sky.

Think of it this way: if you want to observe some particular object along the ecliptic, you only have about a 50% chance of catching it at any given time. But if you wait all night, you can observe almost anywhere along it. (That's not just true for the ecliptic, of course. If you've ever done a Messier marathon, you know that the timing is critical- you start with objects low in the west after sunset and end with objects low in the east near sunrise.)
Oh, yeah, OK. You're really right. I do apologize.
I forgot the rotation of the earth. So even if you fix your camera on tripod, you can take almost 180° panorama from sky, at night, without rotating your camera.
And this amazing picture is an almost 350-360° panorama (except the sun itself). Yes, it's true.

I'm so ashamed.
But I want to be a great astronomer. Can I?

If you want to be an astronomer, you have to consider what it takes to become one. I briefly considered becoming an astronomer myself, but then I realized I would have to work with equations all day (or a lot of the time anyway), and I knew that I couldn't do it. I became an astronomy nerd instead, getting my knowledge from reading and looking at pictures (and asking questions of other people, for example here at Starship Asterisk* - a great learning experience).

Ask yourself if you've got what it takes to become a professional astronomer. If you believe that you do, then go for it! Go to university, and work hard to get the money to do so.

But you should ask someone else, preferably Chris Peterson who is himself an astronomer, how you should go about to become an astronomer yourself.

And remember that even if you end up doing something else than astronomy for a living, astronomy is always there for you, for example here at Starship Asterisk*!

Ann

by **Atabakzadeh** » Mon Mar 06, 2017 5:44 am

Chris Peterson wrote:
Atabakzadeh wrote: and this panorama is 180°
I'm RIGHT.
No, you're not. You're not understanding how the image was made. It's a mosaic made between sunset and sunrise, as the sky was moving. It is possible with such an image to capture all of the ecliptic except about 20° on either side of the Sun, which will be too bright. Compare the image with any decent star map and you'll see that it covers a bit under 300° of starry sky.

Think of it this way: if you want to observe some particular object along the ecliptic, you only have about a 50% chance of catching it at any given time. But if you wait all night, you can observe almost anywhere along it. (That's not just true for the ecliptic, of course. If you've ever done a Messier marathon, you know that the timing is critical- you start with objects low in the west after sunset and end with objects low in the east near sunrise.)

Oh, yeah, OK. You're really right. I do apologize.
I forgot the rotation of the earth. So even if you fix your camera on tripod, you can take almost 180° panorama from sky, at night, without rotating your camera.
And this amazing picture is an almost 350-360° panorama (except the sun itself). Yes, it's true.

I'm so ashamed.

But I want to be a great astronomer. Can I?

by **BDanielMayfield** » Sun Mar 05, 2017 3:07 pm

I'm reminded of the story Flatland. It can be hard to think in 4D.

by **Chris Peterson** » Sun Mar 05, 2017 2:30 pm

Atabakzadeh wrote: and this panorama is 180°
I'm RIGHT.

No, you're not. You're not understanding how the image was made. It's a mosaic made between sunset and sunrise, as the sky was moving. It is possible with such an image to capture all of the ecliptic except about 20° on either side of the Sun, which will be too bright. Compare the image with any decent star map and you'll see that it covers a bit under 300° of starry sky.

Think of it this way: if you want to observe some particular object along the ecliptic, you only have about a 50% chance of catching it at any given time. But if you wait all night, you can observe almost anywhere along it. (That's not just true for the ecliptic, of course. If you've ever done a Messier marathon, you know that the timing is critical- you start with objects low in the west after sunset and end with objects low in the east near sunrise.)

by **neufer** » Sun Mar 05, 2017 2:20 pm

I'm SURE, this is a 360° panorama as below:

1- Look to the sunset horizon
2- Turn your head up slooooowly until you see the sky above your head vertically at midnight.
2-1- Now you covered 180° of observable field. (right angle is 90°)
3- Continue rotating your head behind yourself to see the rest of the sky until you see the sunrise horizon.
3-1 Now you added other 180° to the previous viewed filed of sky.

So 180° + 180° makes 360° of total sky viewed.[/quote]

by **Atabakzadeh** » Sun Mar 05, 2017 7:13 am

neufer wrote:
Chris Peterson wrote:
neufer wrote:
... the question is whether the image as presented covers 360° along the ecliptic
(i.e., is the distance between Antares & Aldebaran half the width of the screen?).
Well, that's not possible with an image that is made over only three days and which excludes the Sun. The Sun is at the western edge of Capricornus, so we are simply unable to record stars over much of Sagittarius and Capricornus. We can't help but to lose about 40° of stellar visibility along the ecliptic to the Sun's glare.
I measure the distance between Antares & Aldebaran to be just slightly less than half the width of the screen.

That qualifies as a full 360° panorama along the ecliptic so far as I'm concerned
regardless of whether land and sea get in the way of seeing Sagittarius & Capricornus.

I'm SURE, this is a 180° panorama as below:
1- Look to the horizon (e.g. west)
2- Turn your head up slowly until you see the sky above your head vertically.
2-1- Now you covered 90° of observable field. (right angle is 90°)
3- Continue rotating your head behind yourself to see the rest of the sky until you see the opposite side of horizon. (be carefull not to fall behind!)
3-1 Now you added other 90° to the previous viewed filed of sky.

So 90° + 90° makes 180° of total sky viewed.

The above method is VERTICAL observation, as this panorama made.
This panorama is NOT HORIZONTAL observation that camera rotates along to the horizon line.
The camera captured sky VERTICALLY.

and this panorama is 180°
I'm RIGHT.

by **Atabakzadeh** » Sun Mar 05, 2017 7:12 am

I'm SURE, this is a 180° panorama as below:
1- Look to the horizon (e.g. west)
2- Turn your head up slowly until you see the sky above your head vertically.
2-1- Now you covered 90° of observable field. (right angle is 90°)
3- Continue rotating your head behind yourself to see the rest of the sky until you see the opposite side of horizon. (be carefull not to fall behind!)
3-1 Now you added other 90° to the previous viewed filed of sky.

So 90° + 90° makes 180° of total sky viewed.

The above method is VERTICAL observation, as this panorama made.
This panorama is NOT HORIZONTAL observation that camera rotates along to the horizon line.
The camera captured sky VERTICALLY.

and this panorama is 180°
I'm RIGHT.

by **Chris Peterson** » Tue Feb 28, 2017 5:57 pm

neufer wrote:
Chris Peterson wrote:
neufer wrote:
... the question is whether the image as presented covers 360° along the ecliptic
(i.e., is the distance between Antares & Aldebaran half the width of the screen?).
Well, that's not possible with an image that is made over only three days and which excludes the Sun. The Sun is at the western edge of Capricornus, so we are simply unable to record stars over much of Sagittarius and Capricornus. We can't help but to lose about 40° of stellar visibility along the ecliptic to the Sun's glare.
I measure the distance between Antares & Aldebaran to be just slightly less than half the width of the screen.

That qualifies as a full 360° panorama along the ecliptic so far as I'm concerned
regardless of whether land and sea get in the way of seeing Sagittarius & Capricornus.

That's fine, if you like that definition. I wouldn't put it that way, since the image and the context lead most people to see this as a sky panorama, and calling it 360° from that viewpoint is confusing and possibly misleading.

by **neufer** » Tue Feb 28, 2017 5:49 pm

Chris Peterson wrote:
neufer wrote:
... the question is whether the image as presented covers 360° along the ecliptic
(i.e., is the distance between Antares & Aldebaran half the width of the screen?).
Well, that's not possible with an image that is made over only three days and which excludes the Sun. The Sun is at the western edge of Capricornus, so we are simply unable to record stars over much of Sagittarius and Capricornus. We can't help but to lose about 40° of stellar visibility along the ecliptic to the Sun's glare.

I measure the distance between Antares & Aldebaran to be just slightly less than half the width of the screen.

That qualifies as a full 360° panorama along the ecliptic so far as I'm concerned
regardless of whether land and sea get in the way of seeing Sagittarius & Capricornus.

by **Chris Peterson** » Tue Feb 28, 2017 5:15 pm

neufer wrote:
Chris Peterson wrote:
neufer wrote: There is also the fact that one reason we can't see either Sun is that the land/sea gets in the way.
In this image, that's only by the design of the imager. It could have included a full 360° and the Sun using the same technique.
Well, yes, but the question is whether the image as presented covers 360° along the ecliptic
(i.e., is the distance between Antares & Aldebaran half the width of the screen?).

Well, that's not possible with an image that is made over only three days and which excludes the Sun. The Sun is at the western edge of Capricornus, so we are simply unable to record stars over much of Sagittarius and Capricornus. We can't help but to lose about 40° of stellar visibility along the ecliptic to the Sun's glare.

by **neufer** » Tue Feb 28, 2017 4:57 pm

Chris Peterson wrote:
neufer wrote:
geckzilla wrote:
I get it now, but it's still a little under 360° due to whatever space the Sun takes up.
There is also the fact that one reason we can't see either Sun is that the land/sea gets in the way.
In this image, that's only by the design of the imager. It could have included a full 360° and the Sun using the same technique.

Well, yes, but the question is whether the image as presented covers 360° along the ecliptic
(i.e., is the distance between Antares & Aldebaran half the width of the screen?).

by **Chris Peterson** » Tue Feb 28, 2017 4:50 pm

neufer wrote:
geckzilla wrote: I get it now, but it's still a little under 360° due to whatever space the Sun takes up.
There is also the fact that one reason we can't see either Sun is that the land/sea gets in the way.

In this image, that's only by the design of the imager. It could have included a full 360° and the Sun using the same technique.

by **neufer** » Tue Feb 28, 2017 4:40 pm

geckzilla wrote:
I get it now, but it's still a little under 360° due to whatever space the Sun takes up.

There is also the fact that one reason we can't see either Sun is that the land/sea gets in the way.
............................................................................................................................
Curiously enough the angular distance between Antares & Aldebaran is almost exactly 180°

so all one really needs is a ruler to measure the full width of the screen.

Code: Select all

                   ecliptic longitude       ecliptic latitude
-------------------------------------------------------------
Antares                249.762°                 -4.570°
Aldebaran               69.789°                 -5.467°

by **geckzilla** » Tue Feb 28, 2017 2:49 pm

I get it now, but it's still a little under 360° due to whatever space the Sun takes up.

by **BDanielMayfield** » Tue Feb 28, 2017 2:09 pm

geckzilla wrote:
Atabakzadeh wrote:
neufer wrote: It's a space time composite shot from sunset west to sunrise east.
So, this should compose a 180 degrees panorama, not a 360 degrees.
Take your camera. Capture from west to east in upward direction. you should take about 10 pictures. Then combine theme.
It creates a 180 degrees panorama. You didn't take pictures from the earth under your feet. You just shoot from sky.
There's an old internet troll where someone pretends to be wrong and say "turn 360 degrees and walk away" and then when people correct them they laugh and tell them they fell for it. The editor made a mistake and is not trolling us, but it made me think of it.

Art (neufer) is right. This is a 4 dimensional sky (spanning three nights) mapped to a 2 dimensional surface. Count up the number of constellations. There's no way to see that many from the Earth's surface at any one time. Plus, you can't see both evening and morning twilight at the same time.

by **geckzilla** » Tue Feb 28, 2017 1:33 pm

Atabakzadeh wrote:
neufer wrote:
Atabakzadeh wrote:
This is 180 degrees panorama, not 360 degrees.
The camera shoot sky from west to east, in upward direction.
If this was a 360 degree panorama, then you could see the earth under your feet.
Am I right?
It's a space time composite shot from sunset west to sunrise east.
So, this should compose a 180 degrees panorama, not a 360 degrees.
Take your camera. Capture from west to east in upward direction. you should take about 10 pictures. Then combine theme.
It creates a 180 degrees panorama. You didn't take pictures from the earth under your feet. You just shoot from sky.

There's an old internet troll where someone pretends to be wrong and say "turn 360 degrees and walk away" and then when people correct them they laugh and tell them they fell for it. The editor made a mistake and is not trolling us, but it made me think of it.

by **Atabakzadeh** » Tue Feb 28, 2017 1:24 pm

neufer wrote:
Atabakzadeh wrote:
This is 180 degrees panorama, not 360 degrees.
The camera shoot sky from west to east, in upward direction.
If this was a 360 degree panorama, then you could see the earth under your feet.
Am I right?
It's a space time composite shot from sunset west to sunrise east.

So, this should compose a 180 degrees panorama, not a 360 degrees.
Take your camera. Capture from west to east in upward direction. you should take about 10 pictures. Then combine theme.
It creates a 180 degrees panorama. You didn't take pictures from the earth under your feet. You just shoot from sky.

by **neufer** » Tue Feb 28, 2017 12:19 pm

Atabakzadeh wrote:
This is 180 degrees panorama, not 360 degrees.
The camera shoot sky from west to east, in upward direction.
If this was a 360 degree panorama, then you could see the earth under your feet.
Am I right?

It's a space time composite shot from sunset west to sunrise east.

by **Atabakzadeh** » Tue Feb 28, 2017 6:48 am

Hello.
This is 180 degrees panorama, not 360 degrees.
The camera shoot sky from west to east, in upward direction.
If this was a 360 degree panorama, then you could see the earth under your feet.
Am I right?

Thank you.

by **alter-ego** » Sun Feb 26, 2017 3:49 am

tomatoherd wrote:Wonderful image. Only one thing could have added a bit to helping me orient: maybe a faint pink line representing the celestial equator across the image....

Here's a pretty accurate mapping of the equator onto the APOD:

by **MarkBour** » Sat Feb 25, 2017 9:46 pm

Nice composition!

So, if I were to go outside on a typical night, and (in central Illinois, USA, the big news would be: "Hey, there aren't clouds everywhere spoiling the view tonight!"), then what is the probability that some time in that night between dusk and dawn, all 7 of our solar planetas would be in view (assuming I had the kind of magnification/brightening that could show them all)? I guess that question boils down to: how much of the plane does the Sun wash out, and what is the probability that on a given night not one of the planets is in that region ...

by **tomatoherd** » Sat Feb 25, 2017 1:49 pm

Wonderful image. Only one thing could have added a bit to helping me orient: maybe a faint pink line representing the celestial equator across the image....

Starship Asterisk*

APOD: All Planets Panorama (2017 Feb 25)

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