APOD: The Milky Way Over Monument Valley (2012 Aug 01)

[APOD Robot]

The Milky Way Over Monument Valley

Explanation: You don't have to be at Monument Valley to see the Milky Way arch across the sky like this -- but it helps. Only at Monument Valley USA would you see a picturesque foreground that includes these iconic rock peaks called buttes. Buttes are composed of hard rock left behind after water has eroded away the surrounding soft rock. In the above image taken about two months ago, the closest butte on the left and the butte to its right are known as the Mittens, while Merrick Butte can be seen just further to the right. High overhead stretches a band of diffuse light that is the central disk of our spiral Milky Way Galaxy. The band of the Milky Way can be spotted by almost anyone on almost any clear night when far enough from a city and surrounding bright lights.

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[Beyond]

I can almost hear a faint echo of the music of Close Encounters of The Third Kind.

[neufer]

I can almost hear a faint echo of the music of Close Encounters of The Third Kind.

"Faint" because it's a long way to Wyoming: http://apod.nasa.gov/apod/ap090729.html

[Beyond]

Hey! These U.F.O. landing sites all look alike to me. And the Butte just left of center looks like it has a nice flat top. So... who knows At least it's a good place to view the Milky Way from, no matter where you're from.

[Ann]

This is a very beautiful picture. We may note that, unlike other pictures taken of this area, this one has been made with a technique that doesn't emphasize the bright stars. That makes it harder to pick out the constellations, but you can more easily see some other features.

One of the easiest deep-sky objects in this picture is the North America Nebula, right above the most obvious "mitten" formation on the ground. Just above the North America Nebula (but not "touching" it) is Deneb, the alpha star in constellation Cygnus.

To the left of the North America Nebula and Deneb you can see a very dark patch, and to the left of that is a rather faint pink region, seemingly with an arc-like "string of pearls" in front of it. This nebula ought to be IC 1396. On the other side of the North America Nebula, to the right of it, are the pink patches of the Gamma Cygni Nebula.

At the "top" of the Arch of the Milky Way is a strange bluish "hook" attached to a faint "line". That is actually the Coathanger asterism!

Towards the lower right part of the Milky Way arch, you can see yellowish patches peeking out. They are parts of the Milky Way bulge. The first really bright such yellowish patch (seemingly crossed by a "line" of stars) contains rich open cluster M11, although I can't pick the cluster out myself.

Inside the next "yellow patch", you can see two brightenings, one of which ought to be star cluster M25. Above them are three pink emission nebulae. The first, diffuse one is probably NGC 6604, the second one is M16 and the third one probably M17.

You can see slightly "plume-shaped" star cloud M24 sitting right in the dark dust lane of the Milky Way. Below M24 is an "arc" of stars, and below that is the Trifid Nebula and the pink Lagoon Nebula. Below that is the bright yellow "Sagittarius star cloud", the optically brightest unobscured part of the bulge of the Milky Way. Above it, on the other side of the Milky Way dust lane, is the large dark Pipe Nebula. One dust lane emerges from the Pipe Nebula, rising and turning to the right, ending at the Antares and Rho Ophiuchi region.

To the right of the bright yellow Sagittarius star cloud (also known as Baade's Window) is anothe ryellow patch, this one with an obvious white, grainy center in it. The white grainy patch is star cluster M7. Above it, inside the dark dust lane of the Milky Way, you can see an elongated patch, which is star cluster M6.

Finally, on the far right you can see an elongated feature. At far left this feature is pink from emission nebulosity, but farther right it turns into what looks like a series of star clusters. This is star cluster NGC 6231, supergiant Zeta1 Scorpii and related nebulosity.

As I said, this is a great picture! I agree that there is something otherworldly about it. It does look like a good landing site for UFOs!

Ann

[Boomer12k]

It is like a rainbow at night...awesome...what type of camera does that take to get a shot like that?

:---[===] *

[fcmbj]

I understood that our galaxy was a relatively flat disc, yet looking at today's picture of the Milky Way, I get the impression that we are not in the same formation - as though we are at a point well above such a disc. Can anyone please explain why?

[ritwik]

how many spiral arms does our galaxy have ? 6, 4 or 2 and how many arms are actually observed
what arm is this one ?
what are the locations on earth to see each arm of our galaxy ?

[ritwik]

It is like a rainbow at night...awesome...what type of camera does that take to get a shot like that?

:---[===] *

here is wally pacholka and his camera http://www.twanight.org/newTWAN/photogr ... 20Pacholka

[Boomer12k]

how many spiral arms does our galaxy have ? 6, 4 or 2 and how many arms are actually observed
what arm is this one ?
what are the locations on earth to see each arm of our galaxy ?

Here is a "YOU ARE HERE" APOD....hold mouse over picture for overlay...
http://apod.nasa.gov/apod/ap080606.html

:---[===] *

[biddie67]

OMG .... absolutely awesome!!!

[FloridaMike]

... awesomeness...

Thanks Ann, I always appreciate your "guided tours".

[orin stepanek]

When I was a kid; we used to be able to see the Milky Way from our front yard in the small town I grew up in! Now I'm lucky to see some of the major constellations! Today's APOD is really neat!

[Chris Peterson]

I understood that our galaxy was a relatively flat disc, yet looking at today's picture of the Milky Way, I get the impression that we are not in the same formation - as though we are at a point well above such a disc. Can anyone please explain why?

Since we are inside the galaxy's disc, we see it as a ring (spanning 360° of sky). Most of the time, part of the ring is below the horizon, so we see what looks like a sort of line of stars going from one part of the horizon to another. If we're outside and can look with our eyes, we really do see what looks linear, but when you map that onto a wide angle image, it almost always appears curved or arch-like. In an image like today's APOD, you have no real reference for where the zenith actually is, or for how many degrees of horizon are actually captured.

[Chris Peterson]

It is like a rainbow at night...awesome...what type of camera does that take to get a shot like that?

Nothing special. Any ordinary consumer DSLR made in the last few years can produce an equivalent image. The ability to recognize a photo opportunity, set up a shot, and process it, however, are not so easily purchased <g>.

[guest123456]

If we are in the plane of the Milky Way, why does it appear as an arch? Also, is the bright section to the right the direction of the center of the galaxy?

Thanks

[StormyKnight]

Beautiful photo. I remember a time when you couldn't see all those lights/glow on the horizon.

[neufer]

how many spiral arms does our galaxy have ? 6, 4 or 2

• 6, 4 or 2 depending upon how one counts.

<<Until recently, there were thought to be four major spiral arms which all start near the Galaxy's center. Two spiral arms, the Scutum–Centaurus Arm and the Carina–Sagittarius Arm, have tangent points inside the Sun's orbit around the center of the Milky Way. If these arms contain an overdensity of stars compared to the average density of stars in the Galactic disk, it would be detectable by counting the stars near the tangent point. Two surveys of near-infrared light, which is sensitive primarily to red giant stars and not affected by dust extinction, detected the predicted overabundance in the Scutum–Centaurus Arm but not in the Carina–Sagittarius Arm. In 2008, Robert Benjamin of the University of Wisconsin–Whitewater used this observation to suggest that the Milky Way possesses only two major stellar arms: the Perseus Arm and the Scutum–Centaurus Arm. The rest of the arms contain excess gas but not excess stars.>>

[b]Observed and extrapolated structure of the spiral arms. The gray lines radiating from the Sun's position (upper center) list the corresponding constellations. [size=135][u][color=#00CFFF]cyan 3-kpc and Perseus Arm[/color] / [color=#40BF00]green Scutum–Centaurus Arm[/color][/u][/size] [size=120][color=#FF307F]pink Carina–Sagittarius Arm[/color] / [color=#6F10FF]purple Norma and Outer arm[/color][/size] [size=100]Two smaller arms or spurs, including: [color=#FF8040]orange Orion–Cygnus Arm[/color] (containing Sun & Solar System)[/size][/b]

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how many arms are actually observed what arm is this one
what are the locations on earth to see each arm of our galaxy ?

Anytime, like here, that you can observe both Cygnus & Sagittarius then, essentially, you can see all the arms:

The highest part of the Milky Way seen here is towards
Kepler's view of Cygnus in our own Orion–Cygnus Spur

The Perseus Arm is to the left.

And to the right, in order, are:

• 1) The Carina–Sagittarius Arm
  2) The Scutum–Centaurus Arm and
  3) The Norma Arm.
  4) The Central Bar

Here is a "YOU ARE HERE" APOD....hold mouse over picture for overlay...
http://apod.nasa.gov/apod/ap080606.html

[neufer]

If we are in the plane of the Milky Way, why does it appear as an arch?

This wide angle shot really needs to be wrapped around you on half a cylinder.

Also, is the bright section to the right the direction of the center of the galaxy?

Yes: http://media.skysurvey.org/interactive360/index.html

[BobbleHeadNed]

Buttes are composed of hard rock left behind after water has eroded away the surrounding soft rock.

I believe that buttes are the remains of extinct volcanos - usually composed of the harder, newer rock (i.e. basalt) that was once the magma/lava core of a volcano and the softer, older rock that was the volcano's cone was partially or mostly eroded away. Does that seem right?

[Chris Peterson]

I believe that buttes are the remains of extinct volcanos - usually composed of the harder, newer rock (i.e. basalt) that was once the magma/lava core of a volcano and the softer, older rock that was the volcano's cone was partially or mostly eroded away. Does that seem right?

No. A butte is typically formed when you have a cap of hard rock (such as basalt) over softer rock (such as sandstone). The caprock protects the underlying material from erosion, so the area outside the caprock erodes faster, leaving behind a columnar or conical structure.

In some cases buttes may be produced by the material left behind in an extinct volcano, or by magma inclusions. But caprock formations are much more common, and are the cause of the buttes in Monument Valley.

[Chris Peterson]

If we are in the plane of the Milky Way, why does it appear as an arch?

Projection is everything. The image on your left is what you'd see at midnight (currently) lying on your back and looking straight up. On an image, we see the horizon as a circle. The second image is the same view four hours later. You can see how the band of the Milky Way changes position. The third view is at the same time as the second, but now looking to the north. In this projection, we flatten out the horizon (which is pretty much how we see it visually) and that makes the Milky Way look like an arch. At this time of the night, when the Milky Way is nearly overhead, the arch looks about the same to the north or south, except that the views are mirrored.

[Devil Particle]

When you click on the "far enough" link a map of sky brightness comes up. Does anyone know what the region of sky brightness off the east coast of Argentina is? It thought the Falkland islands were sparsely populated.

[LocalColor]

Lovely photo. We can see the milky way from where we live, but the tall mountains block out most of it. So this wide horizon photo is very nice to see.

[Chris Peterson]

When you click on the "far enough" link a map of sky brightness comes up. Does anyone know what the region of sky brightness off the east coast of Argentina is? It thought the Falkland islands were sparsely populated.

From the Night Sky Atlas FAQ:

What's all that light near the Falkland islands? For a small set of islands with more sheep than people, how can they possibly generate so much light?

Satellite data also record the offshore lights where oil and gas production is active (visible e.g. in the North Sea, Chinese Sea and Arabic Gulf), other natural gas flares (visible e.g. in Nigeria) and the fishing fleets (visible e.g. near the coast of Argentina, in Japan Sea and near Malacca). Note that their upward emission functions likely differ from the average emission function of the urban night-time lighting that we use so that the predictions of their effects have some uncertainty.