APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

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Expand view Topic review: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by ThePiper » Wed Sep 12, 2012 11:03 am

neufer wrote:Looking South at the Pipe Nebula:
Ok, it's heavy labour and a torture for my poor brain. It would be much easier to live in a flat, 2-dimensional world.
Anyway, I like this photo with the lovely drawing; I'm pipesmoker, in good company with Edwin Hubble. :ssmile:

Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by neufer » Tue Sep 11, 2012 2:49 pm

Chris Peterson wrote:
ThePiper wrote:
Oh no - something is wrong here. Today there's a picture of the Milkyway over Australia where the Pipe nebula is on top (northern) of the galactic Center, as it should be.
Reunion and Australia - both are located southern of the Equator.
This has nothing to do with which side of the equator you're on. The Pipe Nebula is a bit north of the center of the Milky Way. If you make a Milky Way image when you are facing ~west, you'll see the nebula on top; if you're facing ~east, you'll see it on the bottom. "Top" and "bottom" aren't astronomical directions. Imagine a moonrise with a conjunction of Jupiter rising first. You'd say that Jupiter was "above" the Moon, right? But when you get to moonset, on the opposite horizon, Jupiter will appear "below" the Moon. Or for any Moon, the Man (bunny, grandmother, etc) will be flipped in the opposite direction between moonrise and moonset.
http://en.wikipedia.org/wiki/Dark_Horse_%28astronomy%29 wrote: <<The Dark Horse Nebula or Great Dark Horse is a large dark nebula, which as seen from Earth, obscures part of the upper central bulge of the Milky Way. The Dark Horse lies in the southern constellation Ophiuchus (the Serpent Bearer), near its borders with the more famous constellations Scorpius and Sagittarius.

This region of dark nebulae is called Dark Horse because it resembles the side silhouette of a horse and appears dark as compared with the background glow of stars and star clouds. It is also known as "Great" because it is one of the largest (in apparent size) groups of dark nebulae in the sky.

The rear of The Great Dark Horse (its rump and hind legs), is also known as the Pipe Nebula, which itself carries the designation B77, B78, and B59. (The 'B' numbers named after the astronomer Edward Emerson Barnard, who catalogued dark nebulae.) The Snake Nebula extends from the Dark Horse to the Rho Ophiuchus nebulosity.>>

Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by Chris Peterson » Tue Sep 11, 2012 2:35 pm

ThePiper wrote:Oh no - something is wrong here. Today there's a picture of the Milkyway over Australia where the Pipe nebula is on top (northern) of the galactic Center, as it should be.
Reunion and Australia - both are located southern of the Equator.
This has nothing to do with which side of the equator you're on. The Pipe Nebula is a bit north of the center of the Milky Way. If you make a Milky Way image when you are facing ~west, you'll see the nebula on top; if you're facing ~east, you'll see it on the bottom. "Top" and "bottom" aren't astronomical directions. Imagine a moonrise with a conjunction of Jupiter rising first. You'd say that Jupiter was "above" the Moon, right? But when you get to moonset, on the opposite horizon, Jupiter will appear "below" the Moon. Or for any Moon, the Man (bunny, grandmother, etc) will be flipped in the opposite direction between moonrise and moonset.

Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by neufer » Tue Sep 11, 2012 2:34 pm

ThePiper wrote:
eltodesukane wrote:
ThePiper wrote:
Why is the Pipe nebula BELOW the center of the Milkyway? Normally (in my brain) it shoud be on top! :?:
Image was taken from the Piton de l'Eau on Reunion Island, which is in the southern hemisphere.
Oh no - something is wrong here. Today there's a picture of the Milkyway over Australia where the Pipe nebula is on top (northern) of the galactic Center, as it should be.
Reunion and Australia - both are located southern of the Equator.

So: This picture is a joke - isn't it? :roll:
It matters most whether one is facing east or west.

Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by ThePiper » Tue Sep 11, 2012 1:40 pm

eltodesukane wrote:
ThePiper wrote:Why is the Pipe nebula BELOW the center of the Milkyway? Normally (in my brain) it shoud be on top! :?:
Image was taken from the Piton de l'Eau on Reunion Island, which is in the southern hemisphere.
Oh no - something is wrong here. Today there's a picture of the Milkyway over Australia where the Pipe nebula is on top (northern) of the galactic Center, as it should be.
Reunion and Australia - both are located southern of the Equator.

So: This picture is a joke - isn't it? :roll:

Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by Flase » Tue Jun 26, 2012 12:53 am

Guest wrote:Why does the central band of the Milky Way typically appear arching? I would think that from Earth it would appear as a flat line since we are looking at the disc straight on.
I would suggest that it's because it takes so much of the sky that some sort of fish-eye lens is needed. Otherwise it is pretty straight as you say.

Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by Anthony Barreiro » Mon Jun 25, 2012 11:30 pm

I forgot to mention in my earlier post: this is a lovely image, very well composed, and full of interesting things to look at!

Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by Boomer12k » Mon Jun 25, 2012 9:20 pm

M. Perrot... I admire your DEDICATION!!!!!! :mrgreen:

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Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by Boomer12k » Mon Jun 25, 2012 9:17 pm

Great Pic!!!!!!!!


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Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by lup974 » Mon Jun 25, 2012 6:45 pm

Ann wrote:I admire the lovely composition and the wonderful tranquility and also majesty of the scene. And because I am a color nerd, I also admire the lovely colors of the Milky Way. Note the yellow color of the Large Sagittarius Star Cloud, the bright yellow patch at between ten and eleven o'clock. Note the blue color of the Small Sagittarius Star Cloud at about eleven o'clock. Note the pink color of the Lagoon Nebula to the left of the Small Sagittarius Star Cloud and M16 and M17 to the right of it.

Indeed, that's a lovely image!

Ann
I always try to progress in terms of color processing. It's not always easy for someone who comes from photography and not astronomy. This is why your comment makes me particularly happy. thank you Ann :D

Luc Perrot

Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by Dan Schroeder » Mon Jun 25, 2012 6:35 pm

Fantastic photo. One quibble with the caption. Most of the naked-eye stars in the night sky are more than 100 light-years away (but less than 1000).

Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by Anthony Barreiro » Mon Jun 25, 2012 6:25 pm

Guest wrote:Why does the central band of the Milky Way typically appear arching? I would think that from Earth it would appear as a flat line since we are looking at the disc straight on.
You may have noticed that the Sun, Moon, and planets follow an arching path through Earth's sky. This happens because the plane of the Earth's rotation (the equator) is inclined about 23 degrees relative to the plane of the Earth's orbit around the Sun (the ecliptic).

The Milky Way follows a more pronounced arch through the sky because the plane of the Milky Way (the galactic equator) is inclined about 60 degrees relative to the Earth's equator. If you observe the Milky Way at midnight over the course of a year (one orbit of the Earth around the Sun), you will see that it appears low all around the horizon during spring (March and April in the northern hemisphere, September and October in the southern hemisphere) and highest overhead during summer and winter. At midnight during northern winter / southern summer we are looking out away from the galactic center, into the thinner part of the disk of the Milky Way. At midnight during northern summer / southern winter we are looking in toward the galactic center. Because the center of the Milky Way is south of the equator in Sagittarius, southern hemisphere observers are blessed to see all the rich star fields in and around Sagittarius crossing high overhead, whereas in the northern hemisphere the galactic center is low in the sky during the best observing months.

Because of light pollution many people live our whole lives without ever seeing the milky way with our own eyes, or it's a rare treat when we're on vacation. That's sad.

Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by Ann » Mon Jun 25, 2012 5:58 pm

I admire the lovely composition and the wonderful tranquility and also majesty of the scene. And because I am a color nerd, I also admire the lovely colors of the Milky Way. Note the yellow color of the Large Sagittarius Star Cloud, the bright yellow patch at between ten and eleven o'clock. Note the blue color of the Small Sagittarius Star Cloud at about eleven o'clock. Note the pink color of the Lagoon Nebula to the left of the Small Sagittarius Star Cloud and M16 and M17 to the right of it.

Indeed, that's a lovely image!

Ann

Re: Typo

by Moonlady » Mon Jun 25, 2012 5:44 pm

Case wrote:
APOD Robot wrote:Far is the distance, ...
Typo -- should be: “Far in the distance, ...”

Fixed now.

I think "Far is the distance" is so poetic, that it fits with this stunning picture :D

Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by eltodesukane » Mon Jun 25, 2012 5:23 pm

ThePiper wrote:Why is the Pipe nebula BELOW the center of the Milkyway? Normally (in my brain) it shoud be on top! :?:
Image was taken from the Piton de l'Eau on Reunion Island, which is in the southern hemisphere.

Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by ThePiper » Mon Jun 25, 2012 5:13 pm

Why is the Pipe nebula BELOW the center of the Milkyway? Normally (in my brain) it shoud be on top! :?:

Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by Lordcat Darkstar » Mon Jun 25, 2012 5:09 pm

It could be that he exposed the landscape longer to bring out the colors. A good 30 plus seconds could have been necessary to bring out the greens, and in that amount of time the stars would have made short trails making them appear brighter.

Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by luigi » Mon Jun 25, 2012 4:34 pm

And BTW Luc: Awesome photo and congrats! It's a beautiful nightscape. Sometimes beautiful is not enough as an adjective.

Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by luigi » Mon Jun 25, 2012 4:29 pm

Chris Peterson wrote:
lup974 wrote:This consideration is right. So, I checked one of the original raw files (there are 12 to compose this panorama). I had a doubt about the quality of my post processing. But I confirm, on the originals, the stars are brightest in the water than in the sky. God knows why...
I can think of a couple of possibilities. In a long exposure, bright stars tend to saturate, so their apparent brightness in the image is less than their actual brightness. But the reflected stars have their light spread around on more pixels (because the water isn't perfectly still), so the total intensity can be higher, even if no individual pixel actually is brighter.

The other possibility is hardware dependent. Some cameras, like Canons, produce raw images that are nearly good enough for photometric purposes. Others, like Nikons, are notorious for the amount of internal processing that occurs, making them poor for many astronomical imaging applications.
Chris I think your first option is correct. When using a fog filter to make the stars diffuse I got the star colors and they seem much brighter. I think the water acts like a natural diffuser.

Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by Chris Peterson » Mon Jun 25, 2012 4:04 pm

lup974 wrote:This consideration is right. So, I checked one of the original raw files (there are 12 to compose this panorama). I had a doubt about the quality of my post processing. But I confirm, on the originals, the stars are brightest in the water than in the sky. God knows why...
I can think of a couple of possibilities. In a long exposure, bright stars tend to saturate, so their apparent brightness in the image is less than their actual brightness. But the reflected stars have their light spread around on more pixels (because the water isn't perfectly still), so the total intensity can be higher, even if no individual pixel actually is brighter.

The other possibility is hardware dependent. Some cameras, like Canons, produce raw images that are nearly good enough for photometric purposes. Others, like Nikons, are notorious for the amount of internal processing that occurs, making them poor for many astronomical imaging applications.

Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by neufer » Mon Jun 25, 2012 4:01 pm

briandonohue wrote:
Stars don't do vengeance; that is, so far as we know, an exclusively human phenomenon.
http://en.wikipedia.org/wiki/Influenza#Etymology wrote:
<<The word Influenza comes from the Italian language meaning "influence" and refers to the cause of the disease; initially, this ascribed illness to unfavorable astrological influences. Archaic terms for influenza include epidemic catarrh, grippe (from the French, first used by Molyneaux in 1694), and sweating sickness. The 1918 flu pandemic (the "Spanish flu") was an unusually severe and deadly pandemic that spread across the world. Most victims were healthy young adults, in contrast to most influenza outbreaks, which predominantly affect juvenile, elderly, or weakened patients. The pandemic lasted from January 1918 to December 1920, spreading even to the Arctic and remote Pacific islands. Between 50 and 130 million died.>>

Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by geckzilla » Mon Jun 25, 2012 3:51 pm

lup974 wrote:
neufer wrote:
Mactavish wrote:
The astrophotographer reports waiting for nearly two years for the sky and clouds to be just right to get the above shot.
How long did he have to wait for the stars reflected in the lake
to be brighter than the stars in the sky? (Or are those fireflies?)
This consideration is right. So, I checked one of the original raw files (there are 12 to compose this panorama). I had a doubt about the quality of my post processing. But I confirm, on the originals, the stars are brightest in the water than in the sky. God knows why...

Luc Perrot
Could it be that over the time of the exposure the movement of the water made the brightest stars appear elongated and seem brighter?

Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by lup974 » Mon Jun 25, 2012 3:43 pm

neufer wrote:
Mactavish wrote:
The astrophotographer reports waiting for nearly two years for the sky and clouds to be just right to get the above shot.
How long did he have to wait for the stars reflected in the lake
to be brighter than the stars in the sky? (Or are those fireflies?)
This consideration is right. So, I checked one of the original raw files (there are 12 to compose this panorama). I had a doubt about the quality of my post processing. But I confirm, on the originals, the stars are brightest in the water than in the sky. God knows why...

Luc Perrot

Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by biddie67 » Mon Jun 25, 2012 2:23 pm

Beautiful photograph ~~ kudos to the photographer for his persistance! And does the dog belong to the photographer? It looks like he's as patient as his possible owner.

Re: APOD: Milky Way Over Piton de l'Eau (2012 Jun 25)

by briandonohue » Mon Jun 25, 2012 1:53 pm

Stars don't do vengeance; that is, so far as we know, an exclusively human phenomenon.

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