Starship Asterisk*

1901 Photograph: The Orion Nebula

Explanation: By the turn of the 20th century advances in photography contributed an important tool for astronomers. Improving photographic materials, long exposures, and new telescope designs produced astronomical images with details not visible at the telescopic eyepiece alone. Remarkably recognizable to astrophotographers today, this stunning image of the star forming Orion Nebula was captured in 1901 by American astronomer and telescope designer George Ritchey. The original glass photographic plate, sensitive to green and blue wavelengths, has been digitized and light-to-dark inverted to produce a positive image. His hand written notes indicate a 50 minute long exposure that ended at dawn and a reflecting telescope aperture of 24 inches masked to 18 inches to improve the sharpness of the recorded image. Ritchey's plates from over a hundred years ago preserve astronomical data and can still be used for exploring astrophysical processes.

<< Previous APOD

This Day in APOD

Next APOD >>

There appears to be a long tiny vertical panorama along the left edge of the image. It seems there should be a story behind that.... and I'd like to read it.

Bay Area John wrote: ↑Sat Aug 17, 2019 4:28 am There appears to be a long tiny vertical panorama along the left edge of the image. It seems there should be a story behind that.... and I'd like to read it.

I think it's just the distorted emulsion coating along the edge of the glass plate.

There appears to be a comet at left center of the image. Would this be Encke?

Isn't that amazing?!
Look at the detail around the edges of the nebula, and if you stand on your head you can make out "The Running Man Nebula" at bottom...

Here is an 1890's image of the Pleiades, I found...I don't know any details about the photo, sorry...

:---[===] *

Beautiful 1901 image! Has it been compared to images from todays images to see any changes over the last 118 years?

Great picture, Boomer!

For myself, I've literally spent hours trying to find a picture I remember, an old photographic plate of the Orion constellation, where Betelgeuse is almost invisible. The reason for the strange appearance of Betelgeuse in old astronomical photographs is that these photographs were made using blue and ultraviolet-sensitive plates, and Betelgeuse emits so little blue light that it virtually disappeared in those photographs! None of the pictures I found is not the one I was looking for, but they will have to do:


In the picture at left, Orion's Belt with Almilam, Alnitak and Mintaka (above center) is so overexposed that it looks like one elongated blob. The Orion Nebula (center) looks like another blob, and Rigel (center right) is so overexposed that it looks like yet another blob. Bellatrix (top right) and Saiph (center left) look bright. But Betelgeuse, top left, looks really faint, since the photo was made with a blue-sensitive photographic emulsion.

The other picture is the one in which the Horsehead Nebula was first discovered. Two Orion Belt's stars, Alnitak, center left, and Alnilam (top left), look very bright. The Flame Nebula looks like some faint fluff to the lower left of Alnitak. The Horsehead Nebula is just faintly visible as a dark shape to the right of Alnitak.

Astrophotography has come a long way, baby. But unsurprisingly enough, I like those old blue-sensitive pictures.

Ann

Henry Draper would be proud!

When I saw this APOD I almost cried: I've not seen a real astronomical photograph in many years! All they have now are these colorful picture postcard things! Seriously, it was not that long ago that ALL astronomical photographs were black-and-white. Then a very few color images began to appear. And now... But keep in mind that in "seeing" anything astronomical (or indeed, anything at all) we are getting a superficial representation of an incredibly complex reality. We tend to take far too seriously what we see. The extreme example is pictures of galaxies, where we are totally missing most of what is really there!

heehaw wrote: ↑Sat Aug 17, 2019 2:40 pm When I saw this APOD I almost cried: I've not seen a real astronomical photograph in many years! All they have now are these colorful picture postcard things! Seriously, it was not that long ago that ALL astronomical photographs were black-and-white. Then a very few color images began to appear. And now... But keep in mind that in "seeing" anything astronomical (or indeed, anything at all) we are getting a superficial representation of an incredibly complex reality. We tend to take far too seriously what we see. The extreme example is pictures of galaxies, where we are totally missing most of what is really there!

I appreciate modern B&W astronomical images. And I appreciate today's image for its historical interest. But it also shows- profoundly- the huge limitations of film. Any competent imager today can capture so much more with an electronic sensor and a small telescope.

Ann wrote: ↑Sat Aug 17, 2019 12:39 pm Great picture, Boomer!

....
The reason for the strange appearance of Betelgeuse in old astronomical photographs is that these photographs were made using blue and ultraviolet-sensitive plates, and Betelgeuse emits so little blue light that it virtually disappeared in those photographs!
...
Note that you can actually see Barnard's Loop, but Betelgeuse is insignificant to say the least.
...

But isn't Barnard's Loop emitting principally in red wavelengths as well?

Paul

Absolument magnifique !

Orion has been around for that long? pass the ice cold one

orin stepanek wrote: ↑Sat Aug 17, 2019 11:46 am Beautiful 1901 image! Has it been compared to images from todays images to see any changes over the last 118 years?

Sorry for the late reply - here is a gif I made of the 1901 image and an image of it taken in 2017. Clicking it should open a larger version. Over those 116 years, there are a few stars that moved quite a bit!

pferkul wrote: ↑Sun Aug 18, 2019 12:11 am

Ann wrote: ↑Sat Aug 17, 2019 12:39 pm Great picture, Boomer!

....
The reason for the strange appearance of Betelgeuse in old astronomical photographs is that these photographs were made using blue and ultraviolet-sensitive plates, and Betelgeuse emits so little blue light that it virtually disappeared in those photographs!
...
Note that you can actually see Barnard's Loop, but Betelgeuse is insignificant to say the least.
...

But isn't Barnard's Loop emitting principally in red wavelengths as well?
Paul

It absolutely is. My own explanation is that there must be ultraviolet light in Barnard's Arc as well as the dominant red. Remember that it is ultraviolet light that makes hydrogen glow red in the first place. The blue-sensitive emulsion used for the photographic plates was even more sensitive to ultraviolet than to blue light. The ultraviolet component is why Barnard's Arc would have showed up.

Ann

FLPhotoCatcher wrote: ↑Sun Aug 18, 2019 4:45 am

orin stepanek wrote: ↑Sat Aug 17, 2019 11:46 am Beautiful 1901 image! Has it been compared to images from todays images to see any changes over the last 118 years?

Sorry for the late reply - here is a gif I made of the 1901 image and an image of it taken in 2017. Clicking it should open a larger version. Over those 116 years, there are a few stars that moved quite a bit!

Tnx! Looks like the Nebula illumination has changed the most!

FLPhotoCatcher wrote: ↑Sun Aug 18, 2019 4:45 am

orin stepanek wrote: ↑Sat Aug 17, 2019 11:46 am Beautiful 1901 image! Has it been compared to images from todays images to see any changes over the last 118 years?

Sorry for the late reply - here is a gif I made of the 1901 image and an image of it taken in 2017. Clicking it should open a larger version. Over those 116 years, there are a few stars that moved quite a bit!

Very very interesting, FLPhotoCatcher!

Ann

orin stepanek wrote: ↑Sun Aug 18, 2019 10:55 am

FLPhotoCatcher wrote: ↑Sun Aug 18, 2019 4:45 am

orin stepanek wrote: ↑Sat Aug 17, 2019 11:46 am Beautiful 1901 image! Has it been compared to images from todays images to see any changes over the last 118 years? :rocketship:

Sorry for the late reply - here is a gif I made of the 1901 image and an image of it taken in 2017. Clicking it should open a larger version. Over those 116 years, there are a few stars that moved quite a bit!

Tnx! Looks like the Nebula illumination has changed the most! :thumb_up:

I doubt it's changed enough to even measure, let alone see visually. It's not difficult to use two images taken with different technology to evaluate star positions, but it's very hard to do any sort of photometric comparison, given the very different spectral response. The newer image is deeper, and also allows us to see through more dust (probably because of the improved long wavelength response). It's also got more dynamic range.

Chris Peterson wrote: ↑Sun Aug 18, 2019 1:32 pm

orin stepanek wrote: ↑Sun Aug 18, 2019 10:55 am

FLPhotoCatcher wrote: ↑Sun Aug 18, 2019 4:45 am

Sorry for the late reply - here is a gif I made of the 1901 image and an image of it taken in 2017. Clicking it should open a larger version. Over those 116 years, there are a few stars that moved quite a bit!

Tnx! Looks like the Nebula illumination has changed the most!

I doubt it's changed enough to even measure, let alone see visually. It's not difficult to use two images taken with different technology to evaluate star positions, but it's very hard to do any sort of photometric comparison, given the very different spectral response. The newer image is deeper, and also allows us to see through more dust (probably because of the improved long wavelength response). It's also got more dynamic range.

Out of curiosity, I verified visible proper motions exist.
Despite a small, apparent overlap error between the two images, I picked two unnamed stars, ~10.5 mag, which shifted noticeably different from adjacent stars. I looked up their proper motions in the Gaia DR2 and found they had total (RA and Dec) proper motions of 67 mas/yr and 97 mas/yr. So over 116 years, the calculated positions shifted by 8 to 11 arcseconds which are certainly measurable. Also the component RA and Dec proper motions visually agree with Gaia. One star drifts primarily eastward while the other drifts mostly southward.
 

alter-ego wrote: ↑Sun Aug 18, 2019 7:24 pm

Chris Peterson wrote: ↑Sun Aug 18, 2019 1:32 pm

orin stepanek wrote: ↑Sun Aug 18, 2019 10:55 am

Tnx! Looks like the Nebula illumination has changed the most!

I doubt it's changed enough to even measure, let alone see visually. It's not difficult to use two images taken with different technology to evaluate star positions, but it's very hard to do any sort of photometric comparison, given the very different spectral response. The newer image is deeper, and also allows us to see through more dust (probably because of the improved long wavelength response). It's also got more dynamic range.

Out of curiosity, I verified visible proper motions exist.
Despite a small, apparent overlap error between the two images, I picked two unnamed stars, ~10.5 mag, which shifted noticeably different from adjacent stars. I looked up their proper motions in the Gaia DR2 and found they had total (RA and Dec) proper motions of 67 mas/yr and 97 mas/yr. So over 116 years, the calculated positions shifted by 8 to 11 arcseconds which are certainly measurable. Also the component RA and Dec proper motions visually agree with Gaia. One star drifts primarily eastward while the other drifts mostly southward.
 
Star Drifts Over 118 Years.PNG

Thanks for checking that. There are at least two stars that move more than the two circled ones, though they are fainter. The best candidate for having its movement checked seems to be the one at upper-left, near the darkest patch of dust. Is there a good link to a site to check the star's motions?
Just for reference, the moon is about 1860 arcseconds wide, so the star that moved 11 arcseconds in the 116 years moved about 170th of the the moon's diameter. Not very much, it seems.

Thanks for verifying that those two stars are indeed foreground stars, alter-ego!

Ann

FLPhotoCatcher wrote: ↑Mon Aug 19, 2019 4:50 pm Thanks for checking that. There are at least two stars that move more than the two circled ones, though they are fainter. The best candidate for having its movement checked seems to be the one at upper-left, near the darkest patch of dust. Is there a good link to a site to check the star's motions?
...

Yeah, the upper-left star is a swift one. It's angular position change is almost 2x larger → ~20". Just to compare, Bernard's Star angular velocity is ~5x 60x faster than this one. Use the DR2 archive. You'll need to search by name or J2000 RA/Dec (ICRS) coordinates.

Edit: Misread the huge proper motion in declination. Total angular position change in 116 years ~1/3°

Ann wrote: ↑Mon Aug 19, 2019 10:28 pm Thanks for verifying that those two stars are indeed foreground stars, alter-ego!

Ann

You're welcome, Ann. It is true they are foreground stars but it's not clear I verified them as such just from angular proper motions. Checking the parallaxes, the furthest one of the two is 436 light years away.

we are able to compare century old image with current image - only because technologies used at that time created data that can be preserved so long.
will the images captured with current technology & data archived today be preserved for a century and retrievable after 100 years- for similar comparison ?

Nilesh_Pune wrote: ↑Fri Aug 30, 2019 6:44 am we are able to compare century old image with current image - only because technologies used at that time created data that can be preserved so long.
will the images captured with current technology & data archived today be preserved for a century and retrievable after 100 years- for similar comparison ?

If civilization collapses, a great deal of digital information will be lost. Otherwise, most will probably remain accessible.