APOD: Earth During a Total Eclipse of the Sun (2015 Mar 18)

Comments and questions about the APOD on the main view screen.
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APOD Robot
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APOD: Earth During a Total Eclipse of the Sun (2015 Mar 18)

Post by APOD Robot » Wed Mar 18, 2015 4:11 am

Image Earth During a Total Eclipse of the Sun

Explanation: What does the Earth look like during a total solar eclipse? It appears dark in the region where people see the eclipse, because that's where the shadow of the Moon falls. The shadow spot actually shoots across the Earth at nearly 2,000 kilometers per hour, darkening locations in its path for only a few minutes before moving on. The featured image shows the Earth during the total solar eclipse of 2006 March, as seen from the International Space Station. On Friday the Moon will move in front of the Sun once again, casting another distorted circular shadow that, this time, will zip over part of the north Atlantic Ocean.

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daddyo
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Re: APOD: Earth During a Total Eclipse of the Sun (2015 Mar

Post by daddyo » Wed Mar 18, 2015 5:02 am

Beautiful image, but I find the upper left corner really interesting, with a feeling of depth given the layers of clouds almost appearing like mountainscapes.

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alter-ego
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Re: APOD: Earth During a Total Eclipse of the Sun (2015 Mar

Post by alter-ego » Wed Mar 18, 2015 5:37 am

When you add the geometry of shadow, Earth's sphericity and motion, the shadow dynamics are not what you might be thinking.
I also added a Mercator projection of the same shadow region (i.e. where totality is visible)

20-Mar-2015 Solar Eclipse Shadow Region.JPG
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bystander
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Re: APOD: Earth During a Total Eclipse of the Sun (2015 Mar

Post by bystander » Wed Mar 18, 2015 2:13 pm

Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
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Dad is watching

Re: APOD: Earth During a Total Eclipse of the Sun (2015 Mar

Post by Dad is watching » Wed Mar 18, 2015 2:17 pm

In the upper portion of the image, starting on the left, dipping down then up and continuing right, there appears to be an artifact on the image that reminds me of a smoke trail. It is not smoke, of course, but is that an out of focus antenna or some sort of window reflection from inside? What do you think?

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Re: APOD: Earth During a Total Eclipse of the Sun (2015 Mar

Post by FloridaMike » Wed Mar 18, 2015 2:54 pm

Dad is watching wrote:In the upper portion of the image, starting on the left, dipping down then up and continuing right, there appears to be an artifact on the image that reminds me of a smoke trail. It is not smoke, of course, but is that an out of focus antenna or some sort of window reflection from inside? What do you think?
It seemed at first to be a strap or some other object near the camera and out of focus. However, it disappears before obstructing our view of the space station appendage. It is probably a reflection that gets washed out by the brightness of the appendage.
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Re: APOD: Earth During a Total Eclipse of the Sun (2015 Mar

Post by geckzilla » Wed Mar 18, 2015 3:05 pm

FloridaMike wrote:
Dad is watching wrote:In the upper portion of the image, starting on the left, dipping down then up and continuing right, there appears to be an artifact on the image that reminds me of a smoke trail. It is not smoke, of course, but is that an out of focus antenna or some sort of window reflection from inside? What do you think?
It seemed at first to be a strap or some other object near the camera and out of focus. However, it disappears before obstructing our view of the space station appendage. It is probably a reflection that gets washed out by the brightness of the appendage.
If at first something isn't clear: try, try to find another sample. Look at this page. There are two different photos. The second photo is focused on the foreground rather than the background. You can see a strap of some sort at the edge of the window.
Just call me "geck" because "zilla" is like a last name.

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Re: APOD: Earth During a Total Eclipse of the Sun (2015 Mar

Post by Ron-Astro Pharmacist » Wed Mar 18, 2015 3:30 pm

I don't know why I have never noticed the fabric covering the ISS. Looking for answers I found these links. It sounds like it does the trick. Loved the video of how the components were assembled under the link "International Space Station." Covering it, once reassembled, must have been another trick. Ten cm (4in) thick blankets would be hard to "tuck in!"

http://www.theguardian.com/science/2007 ... timradford

http://www.quora.com/What-types-of-mate ... or-made-of
Make Mars not Wars

Remo

Re: APOD: Earth During a Total Eclipse of the Sun (2015 Mar

Post by Remo » Wed Mar 18, 2015 4:52 pm

geckzilla wrote:
FloridaMike wrote:
Dad is watching wrote:In the upper portion of the image, starting on the left, dipping down then up and continuing right, there appears to be an artifact on the image that reminds me of a smoke trail. It is not smoke, of course, but is that an out of focus antenna or some sort of window reflection from inside? What do you think?
It seemed at first to be a strap or some other object near the camera and out of focus. However, it disappears before obstructing our view of the space station appendage. It is probably a reflection that gets washed out by the brightness of the appendage.
If at first something isn't clear: try, try to find another sample. Look at this page. There are two different photos. The second photo is focused on the foreground rather than the background. You can see a strap of some sort at the edge of the window.
I too was curious about the impossible smoke stream -- and I think you folks have solved it -- except that given the straps opaqueness near the station and the rapid narrowing of the strap until it appears both constant width and transparent at the extremity, I suspect that it is more than just the strap is out of focus, but also that it has some sort of movement (oscillation) over the time period of the photo.

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Re: APOD: Earth During a Total Eclipse of the Sun (2015 Mar

Post by Chris Peterson » Wed Mar 18, 2015 5:04 pm

Remo wrote:I too was curious about the impossible smoke stream -- and I think you folks have solved it -- except that given the straps opaqueness near the station and the rapid narrowing of the strap until it appears both constant width and transparent at the extremity, I suspect that it is more than just the strap is out of focus, but also that it has some sort of movement (oscillation) over the time period of the photo.
It was a 1/500 second exposure. I doubt that there was any significant motion blur. The impression of transparency is probably because the strap is so close to the lens that it doesn't fully block more distant rays. Put an opaque strip (like a piece of tape) a few inches from a camera lens that has a larger aperture than the strip width, and you'll get this effect.
Chris

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Remo

Re: APOD: Earth During a Total Eclipse of the Sun (2015 Mar

Post by Remo » Wed Mar 18, 2015 6:57 pm

Chris Peterson wrote:
Remo wrote:I too was curious about the impossible smoke stream -- and I think you folks have solved it -- except that given the straps opaqueness near the station and the rapid narrowing of the strap until it appears both constant width and transparent at the extremity, I suspect that it is more than just the strap is out of focus, but also that it has some sort of movement (oscillation) over the time period of the photo.
It was a 1/500 second exposure. I doubt that there was any significant motion blur. The impression of transparency is probably because the strap is so close to the lens that it doesn't fully block more distant rays. Put an opaque strip (like a piece of tape) a few inches from a camera lens that has a larger aperture than the strip width, and you'll get this effect.
I understand optics. And part of my observation was based on the assumption of a slower shutter speed. Nonetheless, what was the f-stop? (Can't find either the speed, the f-stop or the lens anywhere).

Also, when compared to photo 2, the amount of blur of the strap is far greater in picture 1 when compared to the amount of blur of the background in picture 2 when the blur should be reciprocal. Also, the rapid opaque taper combined with the constant width and transparency at the extreme doesn't correlate. One would expect a sharper image from an object at the extreme, when based on the taper, the extreme was at least 3x farther away.

Notwithstanding, you might be correct; however, at present your explanation does not fully explains the phenomena.

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Re: APOD: Earth During a Total Eclipse of the Sun (2015 Mar

Post by MarkBour » Wed Mar 18, 2015 10:27 pm

Love this APOD! Also, thanks alter-ego for posting that amazing simulation of the upcoming eclipse.
Perhaps I can beat neufer with a post of:
Click to play embedded YouTube video.
Mark Goldfain