APOD: Through the Shadow of the Moon (2015 Apr 14)

Comments and questions about the APOD on the main view screen.
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APOD: Through the Shadow of the Moon (2015 Apr 14)

Post by APOD Robot » Tue Apr 14, 2015 4:05 am

Image Through the Shadow of the Moon

Explanation: What would it look like to fly through a total eclipse of the Sun? On a typical place on Earth in the path of the dark shadow of the Moon during a total eclipse, an observer would see the Moon cross the face of the Sun, completely blocking it for a few minutes. A particularly clear view of the darkness created on Earth during last month's total solar eclipse was captured by an aircraft flying through the Moon's umbral shadow. One second of time in the featured time-lapse video corresponds to about one minute of real time. The Moon's shadow comes in from the right and leaves on the left, all while locations on Earth outside the umbral shadow -- over 100 kilometers away -- remain partly sunlit. During the next solar eclipse in mid-September, the Moon will, at most, block only part of the Sun.

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Re: APOD: Through the Shadow of the Moon (2015 Apr 14)

Post by Boomer12k » Tue Apr 14, 2015 5:13 am

Interesting to see the Terminator come up on you, and pass....great flight.

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Re: APOD: Through the Shadow of the Moon (2015 Apr 14)

Post by astromac » Tue Apr 14, 2015 12:46 pm

It would have been much more interesting without the time lapse - or at least with a much lower figure, like 4?

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Re: APOD: Through the Shadow of the Moon (2015 Apr 14)

Post by geckzilla » Tue Apr 14, 2015 2:03 pm

Boomer12k wrote:Interesting to see the Terminator come up on you, and pass....great flight.
When you capitalize the T, you're talking about Arnold.
Just call me "geck" because "zilla" is like a last name.

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Re: APOD: Through the Shadow of the Moon (2015 Apr 14)

Post by Chris Peterson » Tue Apr 14, 2015 2:20 pm

geckzilla wrote:
Boomer12k wrote:Interesting to see the Terminator come up on you, and pass....great flight.
When you capitalize the T, you're talking about Arnold.
Well, you have to admit, that would be interesting.
Chris

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Re: APOD: Through the Shadow of the Moon (2015 Apr 14)

Post by neufer » Tue Apr 14, 2015 2:27 pm

geckzilla wrote:
Boomer12k wrote:
Interesting to see the Terminator come up on you, and pass....great flight.
When you capitalize the T, you're talking about Arnold.
And when you don't capitalize the T, you're talking The Twilight Zone.
http://en.wikipedia.org/wiki/Terminator_%28solar%29 wrote:
A terminator, twilight zone or "grey line" is a moving line that separates the illuminated day side and the dark night side of a planetary body. A terminator is defined as the locus of points on a Moon or planet where the line through a Sun is tangent.
http://eclipse.gsfc.nasa.gov/SEhelp/SEglossary.html wrote:
umbra - The umbra is the darkest part of the Moon's shadow. From within the umbra, the Sun is completely blocked by the Moon as in the case of a total eclipse. This contrasts with the penumbra, where the Sun is only partially blocked resulting in a partial eclipse.

antumbra - The antumbra is that part of the Moon's shadow that extends beyond the umbra. It is similar to the penumbra in that the Sun is only partially blocked by the Moon. From within the antumbra, the Sun appears larger than the Moon which is seen in complete silhouette. An annular eclipse is seen when an observer passes through the antumbra.

penumbra - The penumbra is the weak or pale part of the Moon's shadow. From within the penumbra, the Sun is only partially blocked by the Moon as in the case of a partial eclipse. This contrasts with the umbra, where the Sun is completely blocked resulting in a total eclipse.
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Steve Dutch

Re: APOD: Through the Shadow of the Moon (2015 Apr 14)

Post by Steve Dutch » Tue Apr 14, 2015 2:29 pm

For the price of the air fare, it's a shame they couldn't have cleaned the windows properly.

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Re: APOD: Through the Shadow of the Moon (2015 Apr 14)

Post by MarkBour » Tue Apr 14, 2015 3:21 pm

So, if Arnold is coming up on you and he starts to block out the sun, the edge of his shadow across your face is the Terminator's terminator ?
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Re: APOD: Through the Shadow of the Moon (2015 Apr 14)

Post by doink » Tue Apr 14, 2015 3:53 pm

MarkBour wrote:So, if Arnold is coming up on you and he starts to block out the sun, the edge of his shadow across your face is the Terminator's terminator ?
You'd really be in the twilight zone then.

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Re: APOD: Through the Shadow of the Moon (2015 Apr 14)

Post by Beyond » Tue Apr 14, 2015 4:16 pm

If you missed the Terminator's terminator, no problemento... He'll be back!
To find the Truth, you must go Beyond.

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Re: APOD: Through the Shadow of the Moon (2015 Apr 14)

Post by ta152h0 » Tue Apr 14, 2015 4:48 pm

Anything like this been done from the ISS ? Too much luck required ?
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Re: APOD: Through the Shadow of the Moon (2015 Apr 14)

Post by alter-ego » Tue Apr 14, 2015 5:55 pm

ta152h0 wrote:Anything like this been done from the ISS ? Too much luck required ?
Yeah. I estimate that it the probability of the ISS orbiting within an umbra to be ~ 1 in 3000 solar eclipses. The Mar 2015 eclipse was pretty close.
On the ISS, totality is much shortened because of the ~8x faster velocity. For the last eclipse, totality would only have lasted <22 seconds.
°`
Edit: The 22-sec totality duration assumes the ISS is traveling the same direction. If the ISS were traveling 90° to the umbra path, the duration would have been 19 seconds.
Last edited by alter-ego on Tue Apr 14, 2015 9:15 pm, edited 1 time in total.
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Re: APOD: Through the Shadow of the Moon (2015 Apr 14)

Post by MarkBour » Tue Apr 14, 2015 7:18 pm

I've seen mention that astronauts are at risk from the Sun's rays, as they are outside of the protective ozone layer and any other radiation-dampening layers. Not having been one, I wonder if it affects their "daily life" in any significant way. For example, staying away from the windows at certain times? Do they take care not to face the sun on spacewalks, etc? (Surely looking right at Sol would be blinding, but we all have that, too. I'm wondering if it causes more trouble to their activities than it does us earthbound mortals.) With a couple of astronauts who have just begun a full year-long shift on the ISS, I wonder what their special concerns are in this regard.
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Re: APOD: Through the Shadow of the Moon (2015 Apr 14)

Post by geckzilla » Tue Apr 14, 2015 7:44 pm

MarkBour wrote:I've seen mention that astronauts are at risk from the Sun's rays, as they are outside of the protective ozone layer and any other radiation-dampening layers. Not having been one, I wonder if it affects their "daily life" in any significant way. For example, staying away from the windows at certain times? Do they take care not to face the sun on spacewalks, etc? (Surely looking right at Sol would be blinding, but we all have that, too. I'm wondering if it causes more trouble to their activities than it does us earthbound mortals.) With a couple of astronauts who have just begun a full year-long shift on the ISS, I wonder what their special concerns are in this regard.
Coincidentally, I was just reading about the South Atlantic Anomaly and it is pertinent to your questions. Satellites and the astronauts are affected. Regarding astronauts specifically:
The International Space Station, orbiting with an inclination of 51.6°, requires extra shielding to deal with this problem. The Hubble Space Telescope does not take observations while passing through the SAA.[6] Astronauts are also affected by this region which is said to be the cause of peculiar 'shooting stars' (phosphenes) seen in the visual field of astronauts.[7]
Just call me "geck" because "zilla" is like a last name.

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Re: APOD: Through the Shadow of the Moon (2015 Apr 14)

Post by Steve Dutch » Tue Apr 14, 2015 10:44 pm

ta152h0 wrote:Anything like this been done from the ISS ? Too much luck required ?
ISS hasn't seen an eclipse but Gemini XII did on November 12, 1966. The Wikipedia article has a partial eclipse photo, and there's a poor quality diamond ring photo on line. The Russian Mir station observed the umbra of the 1999 eclise in Europe but was not in the umbra itself.

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Re: APOD: Through the Shadow of the Moon (2015 Apr 14)

Post by alter-ego » Wed Apr 15, 2015 2:43 am

Steve Dutch wrote:
ta152h0 wrote:Anything like this been done from the ISS ? Too much luck required ?
ISS hasn't seen an eclipse but Gemini XII did on November 12, 1966. The Wikipedia article has a partial eclipse photo, and there's a poor quality diamond ring photo on line. The Russian Mir station observed the umbra of the 1999 eclise in Europe but was not in the umbra itself.
Although the original flight plan to see the eclipse was scrapped because of another activity, a rendezvous was reestablished later. However, they only got to see a partial as born out by their picture(s) and actual times. NASA'a Gemini 12 article states their rendezvous time with the eclipse occurred at about 9:20 EST (14:20 UT) over South America. The umbra did pass through South America but totality occurred between 13:01 UT and 14:11 UT. Given no pictures were made nearer totality and the rendezvous timing is after totality, I don't believe Gemini 12 passed through the umbra.
Gemini 12(Nov 1966) and ISS (Mar 2015) have seen partial eclipses, but apparently not one manned spacecraft as passed through a solar-eclipse umbra.
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Re: APOD: Through the Shadow of the Moon (2015 Apr 14)

Post by K_C » Wed Apr 15, 2015 5:31 pm

Chris Peterson wrote:
geckzilla wrote:
Boomer12k wrote:Interesting to see the Terminator come up on you, and pass....great flight.
When you capitalize the T, you're talking about Arnold.
Well, you have to admit, that would be interesting.
Speaking of T's...

The creators of the video have put one too many T's in the name "Scotland"

Regards

A person from Scotland (and not Scottland)

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Re: APOD: Through the Shadow of the Moon (2015 Apr 14)

Post by Chris Peterson » Wed Apr 15, 2015 5:52 pm

K_C wrote:Speaking of T's...

The creators of the video have put one too many T's in the name "Scotland"

Regards

A person from Scotland (and not Scottland)
A common translation mistake by Germans (where Scotland is called Schottland).
Chris

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