APOD: Airglow, Gegenschein, and Milky Way (2013 Apr 20)

Comments and questions about the APOD on the main view screen.
User avatar
APOD Robot
Otto Posterman
Posts: 4685
Joined: Fri Dec 04, 2009 3:27 am

APOD: Airglow, Gegenschein, and Milky Way (2013 Apr 20)

Post by APOD Robot » Sat Apr 20, 2013 4:13 am

Image Airglow, Gegenschein, and Milky Way

Explanation: As far as the eye could see, it was a dark night at Las Campanas Observatory in the southern Atacama desert of Chile. But near local midnight on April 11, this mosaic of 3 minute long exposures revealed a green, unusually intense, atmospheric airglow stretching over thin clouds. Unlike aurorae powered by collisions with energetic charged particles and seen at high latitudes, the airglow is due to chemiluminescence, the production of light in a chemical reaction, and found around the globe. The chemical energy is provided by the Sun's extreme ultraviolet radiation. Like aurorae, the greenish hue of this airglow does originate at altitudes of 100 kilometers or so dominated by emission from excited oxygen atoms. The gegenschein, sunlight reflected by dust along the solar system's ecliptic plane was still visible on that night, a faint bluish cloud just right of picture center. At the far right, the Milky Way seems to rise from the mountain top perch of the Magellan telescopes. Left are the OGLE project and du Pont telescope domes.

<< Previous APOD This Day in APOD Next APOD >>
[/b]

User avatar
Ann
4725 Å
Posts: 12081
Joined: Sat May 29, 2010 5:33 am

Re: APOD: Airglow, Gegenschein, and Milky Way (2013 Apr 20)

Post by Ann » Sat Apr 20, 2013 5:55 am

Really fascinating. The sky looks almost like a Turner painting. As beautiful as it is, I find it mildly worrying, as if chemicals in the atmosphere are taking over the atmosphere, making it green above those orange clouds. If that green chemiluminescence is getting stronger and stronger, then perhaps the Earth will really begin to look green from space?

The clouds look strange too, as if the sky was on fire.

A faint wisp of a blue smudge - the Gegenschein? - can be seen near picture center around an intrinsically blue star, which I think is Spica.

A surprisingly bright white star(?) can be seen just to the left of the luminous band of the Milky Way. I think that "star" is Omega Centauri. And there is a fine cluster at far left. Is it the Beehive Cluster?

This skyscape is like a glorious painting and almost otherworldly. It's beautiful and strange.

Ann
Color Commentator

User avatar
geckzilla
Ocular Digitator
Posts: 9169
Joined: Wed Sep 12, 2007 12:42 pm
Location: Modesto, CA

Re: APOD: Airglow, Gegenschein, and Milky Way (2013 Apr 20)

Post by geckzilla » Sat Apr 20, 2013 8:00 am

Hopefully chemicals like oxygen which are responsible for this particular chemiluminescence stay in our atmosphere. :wink:
Just call me "geck" because "zilla" is like a last name.

User avatar
fausto.lubatti
Ensign
Posts: 66
Joined: Sun Jan 13, 2013 11:43 am

Re: APOD: Airglow, Gegenschein, and Milky Way (2013 Apr 20)

Post by fausto.lubatti » Sat Apr 20, 2013 10:31 am

It is a very inspiring picture! :-)

User avatar
neufer
Vacationer at Tralfamadore
Posts: 18805
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: Airglow, Gegenschein, and Milky Way (2013 Apr 20)

Post by neufer » Sat Apr 20, 2013 11:29 am

APOD Robot wrote:
Left are the OGLE project and du Pont telescope domes.>>
Ogle, v. t. [From a Dutch word corresponding to G. äugeln to ogle, fr. auge eye; cf. D. ooglonken to ogle, OD. oogen to cast sheep's eyes upon, ooge eye.] To view or look at with side glances, as in fondness, or with a design to attract notice.

"And ogling all their audience, ere they speak." - Dryden.
http://en.wikipedia.org/wiki/Optical_Gravitational_Lensing_Experiment wrote: <<The Optical Gravitational Lensing Experiment or OGLE is a Polish astronomical project based at the University of Warsaw that is chiefly concerned with discovering dark matter using the microlensing technique. Since the project began in 1992, it has discovered several extrasolar planets as a side benefit. The project is led by Professor Andrzej Udalski.

The main targets of the experiment are the Magellanic Clouds and the Galactic Bulge, because of the large number of intervening stars that can be used for microlensing during a stellar transit. Most of the observations have been made at the Las Campanas Observatory in Chile. Cooperating institutions include Princeton University and the Carnegie Institution.

The project is now in its fourth phase. The first phase, OGLE-I (1992–1995), was the project pilot phase; for OGLE-II (1996–2000), a telescope was specially constructed, placed in Las Campanas Observatory and dedicated to the project. The 8-chip mosaic CCD camera was built in Poland and shipped to Chile. OGLE-III (2001–2009) was primarily devoted to detecting gravitational microlensing events and transiting planets in four fields: the Galactic Bulge, the constellation Carina, and toward both Magellanic Clouds. As a byproduct of the constant monitoring of hundreds of millions of stars, the largest catalogs of variable stars were constructed, and the first exoplanets discovered using the microlensing technique were detected. In 2010, following engineering work in 2009, the fourth and current phase, OGLE-IV, was started using a 32-chip mosaic CCD camera. The main goal for this phase is to increase the number of planetary detections using microlensing, enabled by the new camera.

Seventeen planets have so far been discovered by the OGLE project. Eight of the planets were discovered by the transit method and six by the gravitational microlensing method.>>
William Makepeace Thackeray. (1811–1863). Vanity Fair. XXIV. The Old Piano

There are some splendid tailors’ shops in the High Street of Southampton, in the fine plate-glass windows of which hang gorgeous waistcoats of all sorts, of silk and velvet, and gold and crimson, and pictures of the last new fashions in which those wonderful gentlemen with quizzing glasses, and holding on to little boys with the exceeding large eyes and curly hair, ogle ladies in riding habits prancing by the Statue of Achilles at Apsley House.
Art Neuendorffer

User avatar
Beyond
500 Gigaderps
Posts: 6889
Joined: Tue Aug 04, 2009 11:09 am
Location: BEYONDER LAND

Re: APOD: Airglow, Gegenschein, and Milky Way (2013 Apr 20)

Post by Beyond » Sat Apr 20, 2013 11:39 am

Gives a whole new meaning to Googleing.
To find the Truth, you must go Beyond.

User avatar
neufer
Vacationer at Tralfamadore
Posts: 18805
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: Airglow, Gegenschein, and Milky Way (2013 Apr 20)

Post by neufer » Sat Apr 20, 2013 11:56 am

Click to play embedded YouTube video.
Beyond wrote:
Gives a whole new meaning to Googleing.
Art Neuendorffer

Spoonbender
Asternaut
Posts: 4
Joined: Fri Apr 05, 2013 12:56 pm

Re: APOD: Airglow, Gegenschein, and Milky Way (2013 Apr 20)

Post by Spoonbender » Sat Apr 20, 2013 12:22 pm

Ann wrote:Really fascinating. The sky looks almost like a Turner painting. As beautiful as it is, I find it mildly worrying, as if chemicals in the atmosphere are taking over the atmosphere, making it green above those orange clouds. If that green chemiluminescence is getting stronger and stronger, then perhaps the Earth will really begin to look green from space?

The clouds look strange too, as if the sky was on fire.

A faint wisp of a blue smudge - the Gegenschein? - can be seen near picture center around an intrinsically blue star, which I think is Spica.

A surprisingly bright white star(?) can be seen just to the left of the luminous band of the Milky Way. I think that "star" is Omega Centauri. And there is a fine cluster at far left. Is it the Beehive Cluster?

This skyscape is like a glorious painting and almost otherworldly. It's beautiful and strange.

Ann
Is that a city in the distance on the lower left/mid of the picture?

Boomer12k
:---[===] *
Posts: 2691
Joined: Sun Apr 22, 2007 12:07 am

Re: APOD: Airglow, Gegenschein, and Milky Way (2013 Apr 20)

Post by Boomer12k » Sat Apr 20, 2013 12:36 pm

The Southern Sky is always a bit confusing to me. Everything is, kind of Upside Down...But it is still an interesting picture of interesting phenomena, and the Milky Way.

What Chemicals are we talking here????

:---[===] *

User avatar
LocalColor
Science Officer
Posts: 266
Joined: Sat Mar 31, 2012 9:11 pm
Location: Central Idaho, USA

Re: APOD: Airglow, Gegenschein, and Milky Way (2013 Apr 20)

Post by LocalColor » Sat Apr 20, 2013 4:34 pm

Beautiful, thank you Yuri Beletsky.

User avatar
Ann
4725 Å
Posts: 12081
Joined: Sat May 29, 2010 5:33 am

Re: APOD: Airglow, Gegenschein, and Milky Way (2013 Apr 20)

Post by Ann » Sat Apr 20, 2013 7:12 pm

Spoonbender wrote:
Is that a city in the distance on the lower left/mid of the picture?
I don't know, but I don't think so. The picture was taken in the Atacama desert of Chile. That's a very good place for large telescopes, but not for cities. And if there had been a city moderately nearby, I doubt that any large telescopes would have been built there.

To me, that bright yellow light looks almost like reflections on a clear calm lake or the ocean, but again I don't think so. I would guess that we are seeing a cloud bank of some sort, which might reflect the light of the (hidden) Moon.

Ann
Color Commentator

luigi
Ensign
Posts: 93
Joined: Sat Sep 25, 2010 9:59 pm

Re: APOD: Airglow, Gegenschein, and Milky Way (2013 Apr 20)

Post by luigi » Sat Apr 20, 2013 10:09 pm

I like this panoramic view of the southern skies!

Can anyone help me with the position of the Gegenshein please? I previously thought it would be produced towards the North in the South hemisphere, here it is to the west... how do you calculate the position of the Gegenschein in the sky?

Ann: The white big star is Omega Centauri, you are right.

Reference: In this previous APOD from the same photographer and from the South Hemisphere it is towards North (see Andromeda low)
http://apod.nasa.gov/apod/ap080507.html

User avatar
neufer
Vacationer at Tralfamadore
Posts: 18805
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: Airglow, Gegenschein, and Milky Way (2013 Apr 20)

Post by neufer » Sat Apr 20, 2013 11:08 pm

luigi wrote:
Can anyone help me with the position of the Gegenshein please? I previously thought it would be produced towards the North in the South hemisphere, here it is to the west... how do you calculate the position of the Gegenschein in the sky?
"Gegenschein is a faint brightening of the night sky in the region of the antisolar point."
Art Neuendorffer

luigi
Ensign
Posts: 93
Joined: Sat Sep 25, 2010 9:59 pm

Re: APOD: Airglow, Gegenschein, and Milky Way (2013 Apr 20)

Post by luigi » Sun Apr 21, 2013 1:13 am

neufer wrote:
luigi wrote:
Can anyone help me with the position of the Gegenshein please? I previously thought it would be produced towards the North in the South hemisphere, here it is to the west... how do you calculate the position of the Gegenschein in the sky?
"Gegenschein is a faint brightening of the night sky in the region of the antisolar point."
Thanks, then when do you find it North and when West? In this APOD it is on the west and in the other APOD I linked it's in the North.

User avatar
alter-ego
Serendipitous Sleuthhound
Posts: 1043
Joined: Mon Apr 21, 2008 4:51 am
Location: Redmond, WA

Re: APOD: Airglow, Gegenschein, and Milky Way (2013 Apr 20)

Post by alter-ego » Sun Apr 21, 2013 3:47 am

Ann wrote:
Spoonbender wrote:
Is that a city in the distance on the lower left/mid of the picture?
I don't know, but I don't think so. The picture was taken in the Atacama desert of Chile. That's a very good place for large telescopes, but not for cities. And if there had been a city moderately nearby, I doubt that any large telescopes would have been built there.

To me, that bright yellow light looks almost like reflections on a clear calm lake or the ocean, but again I don't think so. I would guess that we are seeing a cloud bank of some sort, which might reflect the light of the (hidden) Moon.
Hi Ann,
I think Spoonbender is right. The yellow brightening on the horizon is at the same heading as Vallenar (population ~47000) which is ~50 kilometers distant. Although visible, the impact on viewing quality is negligible to nothing over the vast majority of the sky. Near-horizon viewing is typically avoided anyway. This is the nearest (an only sizeable) city that likely could be visible from the observatory.
Ann wrote: ... A faint wisp of a blue smudge - the Gegenschein? - can be seen near picture center around an intrinsically blue star, which I think is Spica.

A surprisingly bright white star(?) can be seen just to the left of the luminous band of the Milky Way. I think that "star" is Omega Centauri. And there is a fine cluster at far left. Is it the Beehive Cluster?
As luigi pointed out, you are right about Omega Cen. Yes, the star immersed in the Gegenschein is Spica, and as a bonus, the picture also shows Saturn to the lower right of Spica. It is the first whitish dot you encounter. Oh, and yes, you are correct about the Beehive.
Last edited by alter-ego on Sun Apr 21, 2013 4:16 am, edited 1 time in total.
A pessimist is nothing more than an experienced optimist

User avatar
alter-ego
Serendipitous Sleuthhound
Posts: 1043
Joined: Mon Apr 21, 2008 4:51 am
Location: Redmond, WA

Re: APOD: Airglow, Gegenschein, and Milky Way (2013 Apr 20)

Post by alter-ego » Sun Apr 21, 2013 4:11 am

neufer wrote:
luigi wrote:
Can anyone help me with the position of the Gegenshein please? I previously thought it would be produced towards the North in the South hemisphere, here it is to the west... how do you calculate the position of the Gegenschein in the sky?
"Gegenschein is a faint brightening of the night sky in the region of the antisolar point."
luigi-
In todays APOD, the Gegenschein is towards the northeast, not west. As Art pointed out it tracks the antisolar point. Just as the sun sweeps across the sky during the day, the antisolar point sweeps across the sky at night (in the same direction, but at the negative solar declination). With star charts, you can play around with this basic RA / Dec Gegenschein position calculator to see where the Gegenschein is in the sky.
A pessimist is nothing more than an experienced optimist

luigi
Ensign
Posts: 93
Joined: Sat Sep 25, 2010 9:59 pm

Re: APOD: Airglow, Gegenschein, and Milky Way (2013 Apr 20)

Post by luigi » Sun Apr 21, 2013 6:27 am

alter-ego wrote:
neufer wrote:
luigi wrote:
Can anyone help me with the position of the Gegenshein please? I previously thought it would be produced towards the North in the South hemisphere, here it is to the west... how do you calculate the position of the Gegenschein in the sky?
"Gegenschein is a faint brightening of the night sky in the region of the antisolar point."
luigi-
In todays APOD, the Gegenschein is towards the northeast, not west. As Art pointed out it tracks the antisolar point. Just as the sun sweeps across the sky during the day, the antisolar point sweeps across the sky at night (in the same direction, but at the negative solar declination). With star charts, you can play around with this basic RA / Dec Gegenschein position calculator to see where the Gegenschein is in the sky.
Thank you very much for the calculator, that's what I needed. Now I know where to aim for the Gegenschein. :D

User avatar
Ann
4725 Å
Posts: 12081
Joined: Sat May 29, 2010 5:33 am

Re: APOD: Airglow, Gegenschein, and Milky Way (2013 Apr 20)

Post by Ann » Sun Apr 21, 2013 8:56 am

alter-ego wrote:
I think Spoonbender is right. The yellow brightening on the horizon is at the same heading as Vallenar (population ~47000) which is ~50 kilometers distant. Although visible, the impact on viewing quality is negligible to nothing over the vast majority of the sky. Near-horizon viewing is typically avoided anyway. This is the nearest (an only sizeable) city that likely could be visible from the observatory.
Yes, the star immersed in the Gegenschein is Spica, and as a bonus, the picture also shows Saturn to the lower right of Spica.
Thanks for explaining this, alter-ego! :D



Ann
Color Commentator

Peggy

Re: APOD: Airglow, Gegenschein, and Milky Way (2013 Apr 20)

Post by Peggy » Sun Apr 21, 2013 4:26 pm

Has anyone noticed that if you enlarge and zoom in on the upper left hand corner of the image, that there are at least 4 'cloned' sections of the image?

It looks like it has been Photoshopped.

User avatar
Anthony Barreiro
Turtles all the way down
Posts: 793
Joined: Wed May 11, 2011 7:09 pm
Location: San Francisco, California, Turtle Island

Re: APOD: Airglow, Gegenschein, and Milky Way (2013 Apr 20)

Post by Anthony Barreiro » Mon Apr 22, 2013 10:36 pm

Ann wrote:Really fascinating. ... A faint wisp of a blue smudge - the Gegenschein? - can be seen near picture center around an intrinsically blue star, which I think is Spica.

A surprisingly bright white star(?) can be seen just to the left of the luminous band of the Milky Way. I think that "star" is Omega Centauri. And there is a fine cluster at far left. Is it the Beehive Cluster?

This skyscape is like a glorious painting and almost otherworldly. It's beautiful and strange.

Ann
Aha, so there is Leo, lying on his back hoping someone will rub his belly.
May all beings be happy, peaceful, and free.