APOD: Solar Eclipse Solargraph (2017 Sep 22)

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APOD: Solar Eclipse Solargraph (2017 Sep 22)

Post by APOD Robot » Fri Sep 22, 2017 4:07 am

Image Solar Eclipse Solargraph

Explanation: Today is the September equinox. Heading south, the Sun's path through the sky will cross the celestial equator at 20:02 UT. Of course the equinox date results in (mostly) equal night and day all over planet Earth. But on August 21 the Sun's path through the sky found a little extra-night for some. Made with a drink can pinhole camera and light-sensitive paper, this creative solargraph follows the Sun's path on that date. An all-day exposure, it traces the Sun's arc still rising high in northern skies, aligned with a panoramic snapshot of the local landscape at the bottom. The gap in the arc represents the duration of the partial and total phases of the solar eclipse in clear skies over Lowman, Idaho, USA. There, the extra-night (totality) lasted for about 2 minutes. The broad gap in the Sun's arc also covers the loss of sunlight during the more extended partial eclipse phases.

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Re: APOD: Solar Eclipse Solargraph (2017 Sep 22)

Post by ta152h0 » Fri Sep 22, 2017 6:04 am

is it feasable to obtain an image of the Esarth itself totally eclipsing the Sun and revealing a ring around the Earth ( as well as the space junk ring ) ?
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Re: APOD: Solar Eclipse Solargraph (2017 Sep 22)

Post by geckzilla » Fri Sep 22, 2017 6:14 am

ta152h0 wrote:is it feasable to obtain an image of the Esarth itself totally eclipsing the Sun and revealing a ring around the Earth ( as well as the space junk ring ) ?
I don't think we have that much junk in orbit. If there did happen to be a faint ring, humanity's lights would compete with it. Not that there is any such ring. There probably wouldn't be a ring even if every satellite was shattered to tiny pieces.
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Re: APOD: Solar Eclipse Solargraph (2017 Sep 22)

Post by Boomer12k » Fri Sep 22, 2017 6:28 am

Interesting, but should be "negatized" or actually made a "positive"... to show the Sun as light, and shadow as dark...makes more sense...

Happy Equinox...
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Re: APOD: Solar Eclipse Solargraph (2017 Sep 22)

Post by NCTom » Fri Sep 22, 2017 1:20 pm

Interesting thought. What effects would someone standing on the earth side of the moon looking toward the earth see during a total lunar eclipse? Just as in a lunar eclipse of the sun, I suppose orbital distance would affect the amount of coronal visibility around earth's globe.

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Chris Peterson
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Re: APOD: Solar Eclipse Solargraph (2017 Sep 22)

Post by Chris Peterson » Fri Sep 22, 2017 1:34 pm

NCTom wrote:Interesting thought. What effects would someone standing on the earth side of the moon looking toward the earth see during a total lunar eclipse? Just as in a lunar eclipse of the sun, I suppose orbital distance would affect the amount of coronal visibility around earth's globe.
Yeah. You'd lose most of the corona. You'd see all the sunsets and sunrises on Earth forming a tight ring around the planet's edge. Depending on atmospheric conditions, they might be quite red.

Lunar eclipses have been imaged from the Moon.
img_090218_01.jpg
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Chris Peterson
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Re: APOD: Solar Eclipse Solargraph (2017 Sep 22)

Post by Chris Peterson » Fri Sep 22, 2017 1:41 pm

ta152h0 wrote:is it feasable to obtain an image of the Esarth itself totally eclipsing the Sun and revealing a ring around the Earth ( as well as the space junk ring ) ?
There isn't really a space junk ring. While there are a few high orbit rings, the vast majority of material in orbit around the Earth is in lower orbits at all inclinations, resulting in a spherical cloud. And probably not dense enough to show much in an image.
Space_debris_highlight_std.jpg
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Re: APOD: Solar Eclipse Solargraph (2017 Sep 22)

Post by othermoons » Fri Sep 22, 2017 1:49 pm

This is ART of a high degree, today's apod image. SCIENCE paints our understanding of NATURE. So many possibilities.

As always, thanks APOD

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Re: APOD: Solar Eclipse Solargraph (2017 Sep 22)

Post by Ann » Fri Sep 22, 2017 1:49 pm

Chris Peterson wrote:
ta152h0 wrote:is it feasable to obtain an image of the Esarth itself totally eclipsing the Sun and revealing a ring around the Earth ( as well as the space junk ring ) ?
There isn't really a space junk ring. While there are a few high orbit rings, the vast majority of material in orbit around the Earth is in lower orbits at all inclinations, resulting in a spherical cloud. And probably not dense enough to show much in an image.

Space_debris_highlight_std.jpg
The Earth is becoming a second Saturn. It is growing its own ring.

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Re: APOD: Solar Eclipse Solargraph (2017 Sep 22)

Post by neufer » Fri Sep 22, 2017 5:05 pm

Chris Peterson wrote:
Lunar eclipses have been imaged from the Moon.
It turns out that the L2 Lagrangian point of a planet is quite close to the apex of the planet's umbra cone.

In general the Sun appears larger than the planet by roughly a factor of the [(planetary density)/(4.3 g/cm³)]1/3 at the L2 point.

For the Earth the Sun appears larger by a factor of ~ 1.086 resulting in an annular eclipse at the L2 point.

However, for Mars (with a density of 3.93 g/cm³) the Sun appears larger by a factor of ~ 0.97 resulting in a total eclipse :!:

So: should we send a solar eclipse satellite to the Martian L2 Lagrangian point :?:

Would the Martian elliptical orbit and/or the quasi-stability of an L2 orbit complicate the situation too much :?:
https://en.wikipedia.org/wiki/Lagrangian_point#Spacecraft_at_Sun.E2.80.93Earth_L2 wrote:
<<Sun–Earth L2 is a good spot for space-based observatories. Because an object around L2 will maintain the same relative position with respect to the Sun and Earth, shielding and calibration are much simpler. It is, however, slightly beyond the reach of Earth's umbra, so solar radiation is not completely blocked at L2. (Real spacecraft generally orbit around L2, avoiding partial eclipses of the Sun to maintain a constant temperature). From locations near L2, the Sun, Earth and Moon are relatively close together in the sky; this means that a large sunshade with the telescope on the dark-side can allow the telescope to cool passively to around 50 K – this is especially helpful for infrared astronomy and observations of the cosmic microwave background. The James Webb Space Telescope is due to be positioned at L2.>>
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Re: APOD: Solar Eclipse Solargraph (2017 Sep 22)

Post by MarkBour » Fri Sep 22, 2017 5:27 pm

Boomer12k wrote:Interesting, but should be "negatized" or actually made a "positive"... to show the Sun as light, and shadow as dark...makes more sense...
Happy Equinox...
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As you wish:
sunprintnegated.jpg
I hope I have not violated copyright with this post.
I would have expected the shadow to be shaped differently, it should look like one band crossing another. Perhaps the pinhole method is not sufficiently precise to show the true shape of the time-lapse shadow.
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Re: APOD: Solar Eclipse Solargraph (2017 Sep 22)

Post by bjmb » Fri Sep 22, 2017 9:03 pm

Explanation: Of course the equinox date results in (mostly) equal night and day all over planet Earth.

except at the poles, both of which have midnight sun