APOD: A Blue Blood Moon (2015 Oct 03)

Comments and questions about the APOD on the main view screen.
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APOD: A Blue Blood Moon (2015 Oct 03)

Post by APOD Robot » Sat Oct 03, 2015 4:11 am

Image A Blue Blood Moon

Explanation: This sharp telescopic snapshot caught late September's Harvest Moon completely immersed in Earth's dark umbral shadow, at the beginning of a total lunar eclipse. It was the final eclipse in a tetrad, a string of four consecutive total lunar eclipses. A dark apparition of the Full Moon near perigee, this total eclipse's color was a deep blood red, the lunar surface reflecting light within Earth's shadow filtered through the lower atmosphere. Seen from a lunar perspective, the reddened light comes from all the sunsets and sunrises around the edges of a silhouetted Earth. But close to the shadow's edge, the limb of the eclipsed Moon shows a distinct blue hue. The blue eclipsed moonlight is still filtered through Earth's atmosphere though, originating as rays of sunlight pass through layers high in the upper stratosphere, colored by ozone that scatters red light and transmits blue.

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lo'retiredfart

Re: APOD: A Blue Blood Moon (2015 Oct 03)

Post by lo'retiredfart » Sat Oct 03, 2015 1:39 pm

Are we sure that the blue color is NOT the result of some digital image processor that "auto-balanced" the colors?

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Re: APOD: A Blue Blood Moon (2015 Oct 03)

Post by Chris Peterson » Sat Oct 03, 2015 2:38 pm

lo'retiredfart wrote:Are we sure that the blue color is NOT the result of some digital image processor that "auto-balanced" the colors?
What we know is that the blue color is widely observed and widely imaged.
Chris

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Re: APOD: A Blue Blood Moon (2015 Oct 03)

Post by neufer » Sat Oct 03, 2015 3:19 pm

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Re: APOD: A Blue Blood Moon (2015 Oct 03)

Post by Mokurai » Sat Oct 03, 2015 4:41 pm

Do we have any photos from a lunar orbiter showing the Earth during a lunar eclipse? They should show the lower atmosphere red and the upper atmosphere blue, as described here.

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Re: APOD: A Blue Blood Moon (2015 Oct 03)

Post by Chris Peterson » Sat Oct 03, 2015 4:51 pm

Mokurai wrote:Do we have any photos from a lunar orbiter showing the Earth during a lunar eclipse? They should show the lower atmosphere red and the upper atmosphere blue, as described here.
It's actually a bit more complicated than that. The red makes good sense, given a scattering band of atmosphere (which we know exists). The blue is a little harder to figure, since we're not talking about scatter, but about transmission. So an eclipsed Moon should not look like a dark disk with a red circle around it, and a blue circle above that. It should look like a dark disk with just a red circle, and if you are just short of the transit being total- that is, you are seeing the Sun shine through the atmosphere- you'll see the Sun as blue. A little more into the shadow, or a little more into the Sun you won't see that anymore.
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Re: APOD: A Blue Blood Moon (2015 Oct 03)

Post by Boomer12k » Sat Oct 03, 2015 6:03 pm

Not to mention the Index Refraction.....

Science is sooooooo amazing.....

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Re: APOD: A Blue Blood Moon (2015 Oct 03)

Post by neufer » Sat Oct 03, 2015 6:13 pm

Boomer12k wrote:
Chris Peterson wrote:
Mokurai wrote:
Do we have any photos from a lunar orbiter showing the Earth during a lunar eclipse? They should show the lower atmosphere red and the upper atmosphere blue, as described here.
It's actually a bit more complicated than that. The red makes good sense, given a scattering band of atmosphere (which we know exists). The blue is a little harder to figure, since we're not talking about scatter, but about transmission. So an eclipsed Moon should not look like a dark disk with a red circle around it, and a blue circle above that. It should look like a dark disk with just a red circle, and if you are just short of the transit being total- that is, you are seeing the Sun shine through the atmosphere- you'll see the Sun as blue. A little more into the shadow, or a little more into the Sun you won't see that anymore.
Not to mention the Index Refraction.....
  • The "A Blue Blood Moon" APOD is caused by bright transmission through an absorbing ozone layer.

    However, the center of the umbra produces another (darker) blue moon
    thanks to Rayleigh scattering of the Mesosphere....(not to mention the Index Refraction....).
    --------------------------------------------------------------------------------------------------------------
    APOD: 2014 August 3: Directly behind the shuttle is the mesosphere, which appears blue.
https://blogs.nasa.gov/ISS_Science_Blog/tag/international-partners/page/2/ wrote:

Particles in the upper Earth’s atmosphere cause the blue layer shown in this image of a sunrise taken from aboard the space station. SAGE III will measure these atmospheric gases from a similar perspective. (NASA Image)
http://www.nasa.gov/multimedia/imagegallery/image_feature_2292.html wrote:

Station Crew Sees 'Night-Shining' Clouds
June 26, 2012

<<In both the Earth's Northern and Southern Hemispheres polar mesospheric clouds are at the peak of their visibility, during their respective late spring and early summer seasons. Visible from aircraft in flight, the International Space Station and from the ground at twilight, the clouds typically appear as delicate, shining threads against the darkness of space-hence their other names of noctilucent or "night-shining" clouds.

On June 13, 2012, when this image was taken from the space station as it passed over the Tibetan Plateau, polar mesospheric clouds were also visible to aircraft flying over Canada. In addition to the still image above, the station crew took a time-lapse image sequence of polar mesospheric clouds several days earlier on June 5, while passing over western Asia. It is first such sequence of images of the phenomena taken from orbit.

Polar mesospheric clouds form between 47 to 53 miles (76 to 85 kilometers) above Earth's surface when there is sufficient water vapor at these high altitudes to freeze into ice crystals. The clouds are illuminated by the sun when it is just below the visible horizon, lending them their night-shining properties. In addition to the polar mesospheric clouds trending across the center of the image, lower layers of the atmosphere are also illuminated. The lowest layer of the atmosphere visible in this image-the stratosphere-is indicated by dim orange and red tones near the horizon.>>
Art Neuendorffer

lilaprema

Re: APOD: A Blue Blood Moon (2015 Oct 03)

Post by lilaprema » Sat Oct 03, 2015 9:56 pm

Mokurai wrote:Do we have any photos from a lunar orbiter showing the Earth during a lunar eclipse? They should show the lower atmosphere red and the upper atmosphere blue, as described here.
Yes, Surveyor 3, from the ground. And by humans, Apollo 12, who had come to visit Surveyor 3, took a picture of the earth eclipsing the sun, but from space, on the way home

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Re: APOD: A Blue Blood Moon (2015 Oct 03)

Post by neufer » Sun Oct 04, 2015 3:47 pm

lilaprema wrote:
Mokurai wrote:Do we have any photos from a lunar orbiter showing the Earth during a lunar eclipse? They should show the lower atmosphere red and the upper atmosphere blue, as described here.
Yes, Surveyor 3, from the ground. And by humans, Apollo 12, who had come to visit Surveyor 3, took a picture of the earth eclipsing the sun, but from space, on the way home
  • But it is the (usually overexposed) bright blue sun
    shining through the stratosphere just before eclipse that is involved here.
http://oceanopticsfaq.com/apps/environmental/the-visible-signature-of-ozone-at-twilight/ wrote:

<<It is well known that the ozone layer protects the surface of our planet from the damaging effects of ultraviolet radiation but few people appreciate that, without ozone, the color of the zenith (overhead) sky at twilight would be a pale green/straw yellow rather than the deep, steely blue that we observe. The electronic Chappuis absorption band of ozone is intrinsically weak and has little effect on the color of the daytime sky. This band, extending from 450 to 850 nm, only becomes significant when the pathlength of sunlight through the atmosphere is dramatically increased around sunrise and sunset. At these times, the Chappuis band becomes by far the strongest feature in the visible spectrum of the sky or the setting sun.>>
Art Neuendorffer

Tekija

Re: APOD: A Blue Blood Moon (2015 Oct 03)

Post by Tekija » Sun Oct 04, 2015 8:27 pm

lilaprema wrote:
Mokurai wrote:Do we have any photos from a lunar orbiter showing the Earth during a lunar eclipse? They should show the lower atmosphere red and the upper atmosphere blue, as described here.
Yes, Surveyor 3, from the ground. And by humans, Apollo 12, who had come to visit Surveyor 3, took a picture of the earth eclipsing the sun, but from space, on the way home
Ha, the Japanese did this more recently, in 2009, and in glorius video - but, alas, it is only monochrome.

http://science.nasa.gov/science-news/sc ... yaeclipse/

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Re: APOD: A Blue Blood Moon (2015 Oct 03)

Post by neufer » Sun Oct 04, 2015 9:18 pm

Tekija wrote:
lilaprema wrote:
Mokurai wrote:
Do we have any photos from a lunar orbiter showing the Earth during a lunar eclipse? They should show the lower atmosphere red and the upper atmosphere blue, as described here.
Yes, Surveyor 3, from the ground. And by humans, Apollo 12, who had come to visit Surveyor 3, took a picture of the earth eclipsing the sun, but from space, on the way home
Ha, the Japanese did this more recently, in 2009, and in glorious video - but, alas, it is only monochrome.

http://science.nasa.gov/science-news/sc ... yaeclipse/
https://en.wikipedia.org/wiki/SELENE wrote:

<<SELENE (Selenological and Engineering Explorer), better known in Japan by its nickname Kaguya (かぐや?), was the second Japanese lunar orbiter spacecraft following the Hiten probe. On October 19, 2007, the lunar polar orbiter was in a circular 100 km orbit. Besides a Terrain Camera (with resolution 10 meters per pixel) two 2.2 megapixel CCD HDTV cameras, one wide-angle and one telephoto, were also on board, primarily for public relations purposes. On October 31, 2007, Kaguya deployed its Lunar Magnetometer, Lunar Radar Sounder, Earth-looking Upper Atmosphere and Plasma Imager. Kaguya completed the planned operation by the end of October 2008 and began extended operations. However, because of a degraded reaction wheel, the orbit was lowered to 50 kilometres ± 20 kilometres on February 1, 2009, and impact occurred at 18:25 UTC on June 10, 2009.>>
Art Neuendorffer

Tekija

Re: APOD: A Blue Blood Moon (2015 Oct 03)

Post by Tekija » Sun Oct 04, 2015 9:52 pm

neufer wrote:
Tekija wrote: Ha, the Japanese did this more recently, in 2009, and in glorious video - but, alas, it is only monochrome.

http://science.nasa.gov/science-news/sc ... yaeclipse/
There's the blue, but where's the red?

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Re: APOD: A Blue Blood Moon (2015 Oct 03)

Post by neufer » Sun Oct 04, 2015 11:39 pm

Tekija wrote:
neufer wrote:
Tekija wrote:
Ha, the Japanese did this more recently, in 2009, and in glorious video - but, alas, it is only monochrome.
http://science.nasa.gov/science-news/sc ... yaeclipse/
Kaguya observed the February 9, 2009, penumbral lunar eclipse in living HDTV color
and Kaguya clearly shows an ozone induced blue diamond ring effect.
There's the blue, but where's the red?
Click to play embedded YouTube video.
Art Neuendorffer