Earth at Twilight (APOD 27 Dec 2007)
- orin stepanek
- Plutopian
- Posts: 8200
- Joined: Wed Jul 27, 2005 3:41 pm
- Location: Nebraska
Earth at Twilight (APOD 27 Dec 2007)
http://antwrp.gsfc.nasa.gov/apod/ap071227.html
A stunning view! You can see the thickness of the blue atmosphere at the top. I like the way it seems to narrow as it disappears into the dark side. With out the space program photos like this would not be possible. The Earth is the most beautiful planet I have seen so far. I don't know if we will ever see an exoplanet that may compare.
Orin
A stunning view! You can see the thickness of the blue atmosphere at the top. I like the way it seems to narrow as it disappears into the dark side. With out the space program photos like this would not be possible. The Earth is the most beautiful planet I have seen so far. I don't know if we will ever see an exoplanet that may compare.
Orin
Orin
Smile today; tomorrow's another day!
Smile today; tomorrow's another day!
Earth at Twilight (APOD December 27 2007)
On the right side of the photo the atmosphere is green in a distinct layer beneath the blue layer. I imagine the cause of this might be related to the "green flash", but does anyone have a more complete explanation?
- orin stepanek
- Plutopian
- Posts: 8200
- Joined: Wed Jul 27, 2005 3:41 pm
- Location: Nebraska
The Earth pretty much dominates the view here. I'm sure if you pointed the camera away from the Earth and toward the darkness of space you would see some stars. Longer exposures would probably bring out a few stars but then the picture of Earth would probably get washed out pretty bad.elvis1 wrote:Can some one tell me why in all the pictures I see, like the one today of EARTH, and one in SEPT. of a space walk, the whole background is black but you can not see one STAR, if it is that dark (black) out there I would think that the stars should show in these pictures. thank you.
Orin
Orin
Smile today; tomorrow's another day!
Smile today; tomorrow's another day!
- orin stepanek
- Plutopian
- Posts: 8200
- Joined: Wed Jul 27, 2005 3:41 pm
- Location: Nebraska
I had to use the magnification on my computer to blow the picture up another 400% and I found two more dimmer pixels to the right and a little lower than the one you described so I'm thinking that they must indeed be stars. Nice find BMAONE23.BMAONE23 wrote:Looking at the full size image, I see, near the upper left corner of the picture, what is either a couple of bad pixels or a white and blue star.
I needed to view the full size image as I moved the side bar to pick up the colored pixels
Orin
Orin
Smile today; tomorrow's another day!
Smile today; tomorrow's another day!
A photoshopped enhanced version of the image shows many small dots, with approximately the same distribution "above" the Earth as in the Earth's shadow. That suggests to me that they aren't stars.BMAONE23 wrote:Looking at the full size image, I see, near the upper left corner of the picture, what is either a couple of bad pixels or a white and blue star. I needed to view the full size image as I moved the side bar to pick up the colored pixels
What I can't figure out, though, is the nature of the shadow/dark spot in the lower right corner. The image is said to be taken 4 days before the June 21, 2001 eclipse; so that can't be it.
- DavidLeodis
- Perceptatron
- Posts: 1169
- Joined: Mon May 01, 2006 1:00 pm
I wonder if the 'dark spot' in the lower right could be a small part of an eye of an hurricane?
One thing that is confusing me (easily done I admit!) is that when the "this gorgeous view" is clicked on when online that brings up the image in the Gateway to Astronaut Photography of Earth website. In the image data (under Nadir) it indicates that the image was taken on 2001/06/17 at 21:51:05. However, in a labelled image in that webpage (and others that can be brought up from that webpage) it has the same date but gives a time of 22:33:05. That may be the time when the image was released, but, unless Nadir time is different from normal time, it is confusing.
One thing that is confusing me (easily done I admit!) is that when the "this gorgeous view" is clicked on when online that brings up the image in the Gateway to Astronaut Photography of Earth website. In the image data (under Nadir) it indicates that the image was taken on 2001/06/17 at 21:51:05. However, in a labelled image in that webpage (and others that can be brought up from that webpage) it has the same date but gives a time of 22:33:05. That may be the time when the image was released, but, unless Nadir time is different from normal time, it is confusing.
- NoelC
- Creepy Spock
- Posts: 876
- Joined: Sun Nov 20, 2005 2:30 am
- Location: South Florida, USA; I just work in (cyber)space
- Contact:
Already answered above, but I'll elaborate a bit:elvis1 wrote:Can some one tell me why in all the pictures I see, like the one today of EARTH, and one in SEPT. of a space walk, the whole background is black but you can not see one STAR, if it is that dark (black) out there I would think that the stars should show in these pictures. thank you.
For objects in the sun (e.g., the Earth, or spacewalkers) a VERY short exposure time is required. It's just the same as if you're photographing someone outside on a sunny day - you'll have exposure times like 1/500th of a second. The stars are simply too dim to show in such exposures. By contrast, a night exposure that will show stars can actually be in multiple SECONDS, instead of a small fraction of a second.
The dynamic range of a camera just isn't wide enough to capture both the very dim stars and the sunlit subjects at the same time.
-Noel
- Chris Peterson
- Abominable Snowman
- Posts: 18573
- Joined: Wed Jan 31, 2007 11:13 pm
- Location: Guffey, Colorado, USA
- Contact:
One additional comment: it is often believed that the stars appear exceptionally bright or numerous from space, but in fact, the attenuation of the atmosphere is slight- not more than a few tenths of a magnitude at the zenith. So a camera used in space will respond to stars the same as one used on Earth at night. And the sunlit Earth from space will look the same to the camera as the sunlit ground would from below.NoelC wrote:The dynamic range of a camera just isn't wide enough to capture both the very dim stars and the sunlit subjects at the same time.
This applies also to the APOD showing the Milky Way from an elevation of 5000 meters. Visually, this altitude makes almost no difference to the appearance of the sky. The limiting magnitude is about the same at any dark sky site in the world, regardless of elevation.
Chris
*****************************************
Chris L Peterson
Cloudbait Observatory
https://www.cloudbait.com
*****************************************
Chris L Peterson
Cloudbait Observatory
https://www.cloudbait.com
- orin stepanek
- Plutopian
- Posts: 8200
- Joined: Wed Jul 27, 2005 3:41 pm
- Location: Nebraska
It don't look like a huricane. It may be a thumb of finger, or maybe a shadow from the space station.Qev wrote:Maybe it's the edge of the photographer's thumb?
I have no idea what that could be, otherwise. It's four days off and half the world away from the solar eclipse that occurred the month the photo was taken.
Orin
Orin
Smile today; tomorrow's another day!
Smile today; tomorrow's another day!
-
- Commander
- Posts: 807
- Joined: Thu Jul 21, 2005 2:57 pm
- Location: On a boat near Tacoma, WA, usa
- Contact:
- iamlucky13
- Commander
- Posts: 515
- Joined: Thu May 25, 2006 7:28 pm
- Location: Seattle, WA
There's a couple of good guesses, but this is the one I'd most likely subscribe to. Unless the shadowy feature is something soft-edged in the atmosphere, it's quite out of focus, so it's close to the camera. Even if it were something only slightly further away, like the Quest airlock, it should be in better focus than we see.craterchains wrote:Possibly the edge of the window on the International Space Station.
My first thought had been vignetting from a lens with a small image circle, but the orientation is wrong.
The windows are pretty small on the ISS. The astronauts will be in for quite a treat next year when the cupola gets installed.
"Any man whose errors take ten years to correct is quite a man." ~J. Robert Oppenheimer (speaking about Albert Einstein)
-
- Asternaut
- Posts: 3
- Joined: Sun Jan 20, 2008 12:26 pm