APOD: Hubble 25th Anniversary: Pillars of... (2015 Jan 07)

[geckzilla]

The infrared data is not included in this image. Or am I misunderstanding you? I'm actually putting together a visible + IR image out of the freshly released FITS data right now!

Maybe not. When you follow the Fast Facts link for this image it suggests (strongly) otherwise. But I think that the little image at the bottom describes what they're actually trying to say. Badly. Very, very badly.

I find the image at the bottom says it perfectly. This press release includes not one but two new images. The fast facts page very clearly states what colors were assigned to each filter for each image even without the picture to help explain.

[hughhyatt]

The infrared data is not included in this image. Or am I misunderstanding you? I'm actually putting together a visible + IR image out of the freshly released FITS data right now!

Maybe not. When you follow the Fast Facts link for this image it suggests (strongly) otherwise. But I think that the little image at the bottom describes what they're actually trying to say. Badly. Very, very badly.

Interesting. The text under the image says it's a "visible light snapshot". But the Fast Facts describe what sound like assignment of false colors, and the images at the bottom also seem to imply the same. Also,...

We are also seeing a near IR continuum from 900-1700 nm.

... visible light is 400–700 nm, no?

FYI, I'm a total but long-time (50+ year) amateur.

[geckzilla]

Today's APOD features only visible light and that visible light is from three narrowband passes. One blue (cyan if you are picky) at 502nm and two red at 657nm and 673nm. Today's APOD did NOT include the infrared image which consisted of two wideband near-infrared filters peaking at 1100nm and 1600nm. If you are still confused you can see the raw data at this page:
http://archive.stsci.edu/prepds/heritag ... alist.html

[Ron-Astro Pharmacist]

It's almost as if someone dripped three drops of a red-brown dye and now it's settling through dispersion.

Click to play embedded YouTube video.

Wonder if there is any analogy? I would doubt any gravitational influence from something unseen in the image but there does seem a sense of increasing entropy. It's always seemed, though, that new stars forming represents decreasing randomness. Very confusing to me but an amazing glimpse of our universe-in-action.

[Rusty Brown in Cda]

But, why is the sky blue?

[Chris Peterson]

I find the image at the bottom says it perfectly. This press release includes not one but two new images. The fast facts page very clearly states what colors were assigned to each filter for each image even without the picture to help explain.

Yeah, once you figure it out you can tell what they're trying to say. But it's extremely unclear. One of the worst written explanations I've encountered.

[Visual_Astronomer]

Is it possible to see any movement over the 25 year interval (a mere instant indeed) at this scale? of the gasses themselves or perspective shift as we float by? my guess is not much. We'll simply have to take a photo every twenty five years for the next several million, and have a pretty amazing time-lapse!

The link under the words "spectacular details" (http://heritage.stsci.edu/2015/01/supplemental.html) points out some regions where movement can be seen.

[geckzilla]

I find the image at the bottom says it perfectly. This press release includes not one but two new images. The fast facts page very clearly states what colors were assigned to each filter for each image even without the picture to help explain.

Yeah, once you figure it out you can tell what they're trying to say. But it's extremely unclear. One of the worst written explanations I've encountered.

It's the same as they've always used and I've found it very easy to understand since I began having enough interest in these things to understand them at all. I find it strange that you find it so unclear.

[bystander]

Maybe not. When you follow the Fast Facts link for this image it suggests (strongly) otherwise. But I think that the little image at the bottom describes what they're actually trying to say. Badly. Very, very badly.

Fast Facts at Hubble Heritage make it clear:

About this Image

This image is a composite of separate exposures acquired by the WFC3 instrument on the Hubble Space Telescope. Several filters were used to sample and narrow wavelength ranges. The color results from assigning different hues (colors) to each monochromatic (grayscale) image associated with an individual filter. In this case, the assigned colors are:

Code: Select all

WFC3/UVIS Image of M16

     F502N ([O III]) 	    blue
     F657N (Hα + [N II]) 	green
     F673N ([S II]) 	     red

There are also some interesting comparisons in Supplemental at Hubble Heritage: a mouse over comparison of the UVIS and IR images, as well as comparisons to the 1995 image.

[Visual_Astronomer]

[What you are actually seeing is a complex set of glowing gases. Instead of thinking of what you see as light and shadows coming from the nearby stars, think of the structures themselves glowing gently. There are shadows in a sense because the energy of the stars is what is causing the gas to be energized and emit light so places where the gas does not receive enough energy are not glowing or are glowing more dimly.

I'd say that the dominant thing we are seeing is dust structures, not glowing gases. The dust structures are directly illuminated by stars, and are also seen against a background of ionized gas. The dust casts shadows. I think it's perfectly proper to say that we're seeing light and shadows from nearby stars, just that most of it is stimulated, not reflected or scattered.

If you look at a wider view of the area (e.g.: http://apod.nasa.gov/apod/ap140607.html) it becomes more obvious that we are mostly seeing the silhouette of dust against a background of glowing gas. The infared-only image also reveals this (http://heritage.stsci.edu/2015/01/supplemental.html)

Narrow-band filters, color-mapping and other manipulations allow one to create beautiful works of art, but I constantly have to explain to people that there is no vantage point out in space where you could actually see a scene like this with your eye. With a 20" scope I can just make out a dark V-shape in the middle of a large nebulosity - similar to this image (http://messier.seds.org/Jpg/m16.jpg) but with less detail and not red!

[Chris Peterson]

Narrow-band filters, color-mapping and other manipulations allow one to create beautiful works of art, but I constantly have to explain to people that there is no vantage point out in space where you could actually see a scene like this with your eye.

Indeed, this is true for all nebulas. None can appear to our eyes as anything other than a vague grayish fog with bit of subtle structure visible (think of the Milky Way). Doesn't matter where we observe from, or what kind of purely optical instruments we use. These things are all extremely dim.

[Rules For]

Indeed, this is true for all nebulas. None can appear to our eyes as anything other than a vague grayish fog with bit of subtle structure visible (think of the Milky Way). Doesn't matter where we observe from, or what kind of purely optical instruments we use. These things are all extremely dim.

But wouldn't we see the color emerge through a sufficiently long-exposure photograph? And if so, couldn't we theoretically (though impractically!) also see the color if only we could look through a sufficiently enormous telescope that was able to collect and concentrate enough photons at once?

[Chris Peterson]

But wouldn't we see the color emerge through a sufficiently long-exposure photograph? And if so, couldn't we theoretically (though impractically!) also see the color if only we could look through a sufficiently enormous telescope that was able to collect and concentrate enough photons at once?

Certainly, images capture structure and color. That's how today's image was made. That's what APOD is all about!

But our eyes? No. It doesn't matter how big a telescope you use, what you see will never be brighter than your naked eye sees the same thing. Only larger.

[JohnD]

The UK national newspaper, the Guardian, today published as its centrefold, this APOD image together with an infra red image, said to reveal the young stars.
http://www.theguardian.com/world/pictur ... ion-hubble

John

[Rules For]

But our eyes? No. It doesn't matter how big a telescope you use, what you see will never be brighter than your naked eye sees the same thing. Only larger.

But when I look through a telescope at the Moon, it seems both larger and brighter...?

[sOnIc]

But when I look through a telescope at the Moon, it seems both larger and brighter...?

Larger but not brighter. Your eyes are the primary optics; the scope is secondary; which explains why a larger aperture scope yields brighter images; but ultimately you're actually losing light as a result of using secondary optics.

What about the relative movements of the cloud and its newborn stars? I was under the impression that the nebula continues moving with the same momentum and speed; but leaves the newborn stars behind? Presumably because they have more mass in a smaller space, is that right? And will the newly formed star cluster emerge from the top of this image? So relative to the background, is this cloud going up or down? EDIT: I presume from its appearance that there is a shock front at the top; and a compression in the gas thus forming stars; which implies that the stars will actually emerge from the bottom of the cloud ...? Or relative to the background; the cloud will move in an upward direction; leaving behind a star cluster in essentially the same place where it is now?

[BillBixby]

I've often wondered as I look at APOD photos whether the apparent light and shadows are what my eyes tell me they are. (And the "Pillars of Creation" seem the most extreme example.) Are there really bright light sources where they appear to be, in this case, behind and above the subject structure? Do they really cast what look like shadows in the photo? Are there no bright light sources in front of or below the structure to cast light where there those shadows appear?

What you are actually seeing is a complex set of glowing gases. Instead of thinking of what you see as light and shadows coming from the nearby stars, think of the structures themselves glowing gently. There are shadows in a sense because the energy of the stars is what is causing the gas to be energized and emit light so places where the gas does not receive enough energy are not glowing or are glowing more dimly.

Very interesting! Thank you, Geck!

If a star has gone super nova and its shock-wave disrupted the pillers - is it likely the disruption would cause much of the gas and dust to fall together and form an area of many new stars?

[another poster]

I'm actually putting together a visible + IR image

It's already done: here.

[geckzilla]

I'm actually putting together a visible + IR image

It's already done: here.

No, it wasn't. Not as a single, combined, three-color image. Here is the one I created earlier today.

[JohnD]

You mean like the one from NASA, published in todays Guardian and linked to in my posts above?
John

[geckzilla]

You mean like the one from NASA, published in todays Guardian and linked to in my posts above?
John

That one was just infrared. It was also only two colors.

[Chris Peterson]

But when I look through a telescope at the Moon, it seems both larger and brighter...?

It seems brighter because you are taking in more photons which are covering more of the back of your eye. But the surface brightness (that is, the brightness per unit area on your retina) can never be higher with a telescope than it is without one. Good thing, or you could go blind looking at the Moon telescopically!

[rstevenson]

Who's to say the pillars are not living creatures except people whose minds are dwarfed through lack of imagination, which, Einstein said, was more important than knowledge.

So you're starting a conversation by saying that anyone who disagrees with the idea that "the pillars are ... living creatures" has a mind "dwarfed through lack of imagination"? It's going to be a very short conversation.

Rob

[Nitpicker]

Who's to say the pillars are not living creatures except people whose minds are dwarfed through lack of imagination, which, Einstein said, was more important than knowledge.

So you're starting a conversation by saying that anyone who disagrees with the idea that "the pillars are ... living creatures" has a mind "dwarfed through lack of imagination"? It's going to be a very short conversation.

Rob

Freemind, it depends on what you mean by "living" and "creature". Stars are creations that are said to be born, have a life and die. And I suppose one could describe these pillars as pre-natal stars, although for some reason they are commonly described as stellar nurseries. The word "creature" can be used to describe anything existing, so I'd accept a description of the pillars as "living creatures", though I'd think it was a poor description, easily mistaken for other possible connotations.

[Rusty Brown in Cda]

Can anyone explain why the sky in the background is blue instead of the usual black?