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Unmanned _ Lunar Exploration _ Full Lunar Eclipse Feb 20/21 / Earth picture

Posted by: bjb Feb 7 2008, 10:26 PM

I see we have a full lunar eclipse coming on Feb 20/21 (depending where you live).

I know that even during a full eclipse the Moon is still visible with a coppery hue, due to the refraction of light around the Earth.

Now that we have a bunch of probes in orbit of the Moon, is there any plan / is it possible to take an image of the Earth from the Moon during totality? (or has this already been done?)

I would think that a picture of the Earth surrounded by a red ring would be amazing!

Posted by: brellis Feb 7 2008, 10:32 PM

I read somewhere that it will be possible to see both the setting sun and the rising orange moon in Los Angeles that evening. I'm curious how high you have to be to get that view - it might be the perfect time to visit Griffith Observatory!

Posted by: ugordan Feb 7 2008, 10:44 PM

QUOTE (bjb @ Feb 7 2008, 11:26 PM) *
Now that we have a bunch of probes in orbit of the Moon, is there any plan / is it possible to take an image of the Earth from the Moon during totality? (or has this already been done?)

Now that sounds like a perfect job for Kaguya's HDTV camera. Depending on the totality duration the numbers might not work out, but my hunch tells me Kaguya should be able to witness at least one Earthrise/set if the totality is over 1 hr in duration.

That ought to be a spectacular sight, a brilliant orange ring of light rising over a dark, blood-red lunar horizon. I wonder what the topography would look like at that phase and lightning intensity. Certainly sounds like an awesome shot to take if available.

Posted by: FordPrefect Feb 7 2008, 10:56 PM

Interesting thought! In the past I was too wondering how a total lunar eclipse would look from the moon. Let's cross the fingers Kaguya will be able to take some (stunning?) HDTV shots of this event. Though the timeline is pretty tight, especially when considering that Kaguya needs about 120 minutes for one revolution.

Posted by: DDAVIS Feb 7 2008, 11:24 PM

>I read somewhere that it will be possible to see both the setting sun and the rising orange moon in Los Angeles that evening.

And what a sight! It looks like the Moon will just be entering the inner dark shadow as it rises.

>I'm curious how high you have to be to get that view - it might be the perfect time to visit Griffith Observatory!

Griffith might be nice, but I don't recall if the mountains at the observatory block the eastern horizon. I recall hiking to a lookout point a couple miles east of the Observatory when trying to see the clouded out Annular eclipse and we were looking down on it against the city background. I would at any rate suggest getting away from the city lights as much as possible. I fear that only the latter portion of totality will be seen in or close to a night time sky from Southern California. (I am in Palm Springs)

I love Lunar eclipses, the subtle colors visible inside the Earth shadow can be seen by the human eye better than what all but the most dedicated photographic efforts can record. I think rapidly shot RGB filtered grayscale images should do the job but practically all film and most digital images I have seen render the shadows as little more than a garish red orange. I have in the past 30 years of taking down color observations at one time or another seen muted examples of color from the entire spectrum within the umbra region. I have seen some video images which do surprisingly well despite the limited exposure latitude inherent to that medium.

A summary of my observations of the last such eclipse can be seen at the top of this page:

Earlier Lunar Eclipse observations are at the bottom of this page:
This starts with a made-for-print reproduction oil painting exaggerating the colors, and later digital efforts aspiring to capture a visual impression on the screen.


Posted by: NGC3314 Feb 8 2008, 05:54 PM

QUOTE (bjb @ Feb 7 2008, 04:26 PM) *
Now that we have a bunch of probes in orbit of the Moon, is there any plan / is it possible to take an image of the Earth from the Moon during totality? (or has this already been done?)

Surveyor III was able to get some variously filtered images of an eclipse in 1966. One color-composite version is shown Of course, HDTV would be Really Cool if it can be done...

Posted by: edstrick Feb 9 2008, 06:44 AM

"Surveyor III was able to get some variously filtered images of an eclipse in 1966. One color-composite version is shown"

A couple years <or decades, it feels like now> I posted here a considerably improved pair of the Surveyor 3 images, reassembled from good quality black and white color separations published in JPL TR series reports on Surveyor.

The image linked to had massive overexposure saturating part of the bright limb and "blooming" of the overexposed image on the vidicon detector. The original NASA Press Release image was horrible, even given that data's blooming problem.

The other image was actually the much better image but was never press released in color. In my reconstruction, you can see parts of the faint blue ring of upper atmospheric scattering of sunlight with orange-red blobs where gaps in clouds on the limb let direct sunlight get refracted around the limb to reach the camera.

I've tried poking around the archives here and I don't find the post. It's not on my internetting computer at the moment, so I'll have to dig for it.

Posted by: brellis Feb 9 2008, 07:07 AM

Posted by: dvandorn Feb 21 2008, 04:04 AM

Everyone, quickly, get on your knees and pray! Some great evil monster has swallowed up the Moon!


All seriousness aside, it's a really visually stunning eclipse. I don't have the proper imaging equipment, or I'd take a pic and share it. As of about five minutes ago, there was a nice bright white rind along the southeast limb, and the rest of the face of the Moon was colored a lovely shade of copper... *grin*...

-the other Doug

Posted by: ilbasso Feb 21 2008, 04:17 AM

Strange coincidence - Apollo 12 witnessed a solar eclipse while carrying back from the Moon the camera of Surveyor III, which had also photographed a solar eclipse.

Beautiful eclipse tonight! I hope lots of folks got to see it.

Posted by: laurele Feb 21 2008, 06:39 AM

"Beautiful eclipse tonight! I hope lots of folks got to see it."

Here in New Jersey, we really lucked out with the weather tonight. The astronomy club I belong to scheduled an eclipse viewing event, and when we first arrived, there were a lot of clouds, and the moon kept alternating between being visible and totally obscured. It was also somewhat hazy. But by the time the eclipse really got underway, the sky had totally cleared to the point that we had what is probably the clearest sky possible at the observatory, which is not in a dark sky location. Everybody was thrilled with the beautiful view, and we had the opportunity to see it with binoculars and telescopes people had brought. Since the sky got so clear, we used the observatory's 24 inch telescope to view Saturn along with several of its moons. The only drawback was it was quite cold, probably in the 20s. Still, viewing this eclipse was a wonderful experience, and I can't wait to see the pictures several club members took.

Posted by: dvandorn Feb 21 2008, 06:50 AM

QUOTE (laurele @ Feb 21 2008, 12:39 AM) *
The only drawback was it was quite cold, probably in the 20s.

While I got a good view of this eclipse, I didn't take a long one. Here in Frostbite Falls... er, um, Minneapolis, Minnesota, it was about four below zero F (~20 below C) during mid-eclipse. It's down to about 10 below now (somewhere around 23 below C)... good for clear air, not so good for comfortable outdoor viewing.

-the other Doug

Posted by: tedstryk Feb 21 2008, 12:27 PM

I had a view of the eclipse for a while (in other words, between clouds). Here are a few shots (I haven't even downloaded all the pictures from the camera yet).

Posted by: Ant103 Feb 21 2008, 05:25 PM

Very clear sky over Marseille in France.

Some pictures taken this night :

Rising over Puget Mount at 19:00 :

Before entering the shadow of the earth, Regulus and Saturn are following the very bright moon :

And some eclipse phasis :

Posted by: Ant103 Feb 21 2008, 05:27 PM

Continuing the diving into the shadow

Saturn and Regulus began to lightens more:

Shadow progress :

Sort of color that I like :

And finally, full eclipse :

Posted by: Ant103 Feb 21 2008, 05:29 PM

Larger view to see stellar field :

And labels :
The ending :

A recapitulative board with view center on Earth shadow :

Avec l'ombre de la Terre :

Some humidity this ending night (this is the reflector I used to put my numeric camera in parallel):

Posted by: Floyd Feb 21 2008, 07:23 PM

Very nice Ant! Exactly how it looked in Boston.


Posted by: djellison Feb 21 2008, 08:46 PM

I wonder how Chang'e and Kaguya came thru it.


Posted by: DDAVIS Feb 21 2008, 10:57 PM

The eclipse began under a rare rainy sky in Palm Springs, Calif., and as totality began I dispaired of seeing the event. The skies then cleared about a third of the way through totality and I set up my 6 inch reflector, binocculars, video camera and drawing stuff. I hastily drew isophotes on a set of printed out full moon images within which color and brightness information could be noted, using the WWV time signal.
I notice again the tendency of even excellent digital camera pictures to shift the color balance toward garish oranges and reds. The reality as seen by at least this pair of eyes is more subtle and varied. I used the video later to help in drawing the tonal values within the shadow.
This eclipse, at least starting at mid totality, appeared fairly muted in the intensity and range of colors within the Earth shadow. The southern portion near the shadow boundary was a light golden yellow, and the eastern part of the disk displayed a nice spectral gradation to muted orange and duller rusty red. The western Moon shadow colors at that time were less saturated, duller, with a sharper gradation to the dark brown shadow core, or umbra region. The brighter western colors faded in the latter part of totality, and a pale gray lighting appeared along the SW limb, displaced N from the closest part of the shadow edge, shortly before totality ended. As the sunlit Moon returned the shadow colors moved off the disk and faded in the brightning sky. (P.S. I'm having trouble uploading an image file-it never stops telling me it's uploading)


Posted by: Doc Feb 22 2008, 09:37 AM

Curse the tropical climate mad.gif

The eclipse was scheduled to take place at 4am here in Dar es Salaam.
There was not a single cloud in the sky at midnight so you can imagine my dismay and frustration when a cloud cover developed and did not let up till sunrise!

By then the moon had set...great pictures Ant. how I wish I could have seen it myself.

Posted by: DDAVIS Feb 23 2008, 12:34 AM

Ha! used another browser....Here is an attempt at my visual impression of the Lunar eclipse.

Posted by: dvandorn Feb 23 2008, 06:06 AM

Yes! Your 3:38 and 3:51 images are *exactly* what I saw with my naked eye. A coppery feel to the whole scene, edging to an ochre-ish gold along the southeast limb.

-the other Doug

Posted by: Sunspot Feb 23 2008, 08:51 AM

This was the best I got, quite a lot of high cloud so very hazy, cloud thickened approaching totality didn't see anything there after sad.gif


Posted by: Stu Feb 23 2008, 08:59 AM

Eclipse was due between 01.30 and 05.00 here, so I took the next day off work in anticipation of being too tired after watching the eclipse to function... needn't have bothered, because after 2 weeks of almost perfectly clear nighttime skies here in the Lakes the cloud rolled back in Wednesday night like that scene from Independance Day when the alien ship glides over the mountains, and by 2am next morning the sky was just a flat dome of orange. No hope of seeing anything.

Then to rub salt into the wound, I couldn't even enjoy my day off because a workman spent the whole day digging up my living room floor, looking for the water pipe that was leaking into the shop beneath my flat, so I spent the whole day tramping around town keeping out of his way, in the rain, going back every hour to find yet more devastation...


Posted by: edstrick Feb 23 2008, 11:14 AM

Great weather tuesday night, good weather thursday night, BLOTTO wednesday night. grrrrrrr.

Posted by: JTN Aug 21 2008, 11:04 PM

(Another ancient thread rises from the dead...)

QUOTE (edstrick @ Feb 9 2008, 07:44 AM) *
"Surveyor III was able to get some variously filtered images of an eclipse in 1966. One color-composite version is shown"

A couple years <or decades, it feels like now> I posted here a considerably improved pair of the Surveyor 3 images, reassembled from good quality black and white color separations published in JPL TR series reports on Surveyor.
I've tried poking around the archives here and I don't find the post. It's not on my internetting computer at the moment, so I'll have to dig for it.

Did this ever come to light? I'd be interested to see it.

Random Googling found some (bottom of page) that look rather more interesting than the No idea of provenance (I assume Surveyor 3 data is not available online, in general).

Posted by: scalbers Dec 12 2015, 10:53 PM

For fun I can update this 7 year old thread to mention I'm working on a lunar eclipse model. It's possible for me to render images of the moon seen from Earth, and I'm starting to work on the Earth seen from the moon. Here is a work in progress of a view of Earth from the moon just barely inside the umbra. It still has a bit of aliasing to address. Careful inspection will show a white outer ring, a bluish middle region (from ozone) and a darker red inner region (within the troposphere). This run is without clouds, but does have some stratospheric aerosols.

More on the model is here:

Posted by: JohnVV Dec 13 2015, 05:39 AM


Celestia gives i interesting view for the April 4 2015 eclipse
-- as seen from the Moon - and like the above image they are dark

now there is limited atmosphere simulation at a distance

Posted by: scalbers Dec 17 2015, 08:46 PM

Thanks for the Celestia view. This provides a reminder that it would be nice to add in a representation of the solar corona, as the brightness range of the rendered image allows.

I mentioned this model in passing to Emily at the AGU conference and she posed the question of whether Earth city lights would be visible on the moon during totality. As an example, I found a where it states Tokyo would appear +23.7 magnitude from 30AU away. This translates to about magnitude +9.8 as seen from the moon, below naked eye visibility. Additionally I believe there would be significant glare from the ring of light refracting through Earth's atmosphere making this more difficult to see in practice, depending on how deeply immersed the observer is in the umbra. The apparent magnitude of the developing ring is about -20 for an observer on the edge of the umbra and -15 for an observer in the center (about the full moon seen from Earth). The latter value is somewhat tricky to specify due to the deep red color, meaning the apparent magnitude can deviate from the "visual" V-band magnitude.

Here is an image similar to post #27 with some of the antialiasing measures applied:

In this view around the edge of the umbra the brightness is scaled so the unattenuated (and non-limb darkened) sun is white with 255 RGB counts. When we go to the center of the umbra the red ring faintly shows up with 17 counts in the red channel, somewhat more than 100 times surface brightness reduction in the red channel. This looks pretty dim even when I crank up my monitor brightness. So it's barely possible to show the full dynamic range involved. The second image shows this as a blinking comparison between edge of umbra and center of umbra views. This is a good test of one's monitor contrast. It's also possible to scale up the brightness of the image while you're displaying it to see the red ring better.

(UPDATED Jan 3, 2016)

Posted by: scalbers Dec 23 2015, 03:52 PM

With several further refinements, here is now an animation of the eclipse seen from the moon:

To deal with the brightness range, during the partial eclipse and shallow total eclipse (as seen from this point on the moon) the brightness is scaled so that 255 is the surface brightness of the center of the sun. When we are more inside the edge of the umbra the brightness is scaled up by a factor of 10.

In reality the red ring would be broken up by clouds so here is a movie that shows this with some idealized cloud locations. The handling of solar limb darkening is also improved. Extra frames are added near the end of the total eclipse.

The solar corona is relatively much dimmer than the rest of the scene being shown. It seems it would barely register more than a count or two unless the brightness scale is cranked up further. Unlike the view of a solar eclipse and diamond ring effect from the Earth, there is less opportunity to view the inner corona from the moon due to the large size of the Earth's silhouette. Thus the diamond ring seen from the moon is essentially the refracted light passing through the thin layer of the Earth's atmosphere.

I like to view these animations full screen with the monitor brightness turned up. The view might resemble wearing sunglasses or a solar filter depending on the stage of the eclipse. Even in deep totality the surface brightness could be fairly bright in spots, kind of like a sunset on Earth. I'm presently assuming clean air so adding tropospheric aerosols may dim things a bit more when we're in deep totality.

(UPDATED Jan 2, 2016)

Posted by: scalbers Jan 2 2016, 03:28 PM

Below we can see both the total and partial phases of the eclipse seen from the moon. During the partial phase the sun's disk is set to about 255 counts. During the total phase, the brightness is increased depending on how deeply in the umbra the observer is located, up to a factor of 70 for center of the umbra perspective.

It's interesting to see a somewhat different presentation in this actual as explained in this This is an (even more) unusual situation with the brightness turned up more than in my animation, viewed by Kaguya while significantly outside the edge of the umbra. We know this by the overwhelming image brightness once the uneclipsed part of the sun rises above the moon's limb. The bright part of the sun is initially hidden by Earth/Sun rise on the moon's limb. We are seeing a more complete blue/white ring in the video at this stage than in my animation. This appears to be from scattered light in Earth's atmosphere, and isn't yet included in my posted images, as in more "normal" situations in the umbra it would be relatively faint to see next to the brighter refracted sunlight. It could be added in for completeness, on the low end of the brightness scale or in 16-bit imagery. Scattered light is a small enough component of the total so it doesn't too much affect the appearance of the moon seen from Earth. However when viewing the Earth from the moon, selected areas such as the "ring" away from the "diamond" (particularly if refracted sunlight isn't present) could have a noticeable amount, as in the Kaguya case. This is an eclipse of the sun by both Moon and Earth! I'm experimenting with a simple Rayleigh scattering addition and it looks reasonably dim. Adding Mie scattering from high altitude aerosols may boost the brightness some.

The simulation perhaps better matches some of the (bottom of link).

Posted by: DDAVIS Dec 15 2016, 05:25 AM

As noted above, Lunar eclipses are a favorite subject of mine. Here is an animated study of the visual aspects of Lunar eclipses set to music I recently created. My impression of the appearance of the Earth from the Moon in such circumstances is highlighted, a sight that I hope that will one day be properly captured with a suitable high dynamic range camera.

Posted by: scalbers Dec 16 2016, 01:07 AM

Very nice and engaging presentation of the various viewpoints by DDAVIS.

With this inspiration I'm taking another look at the atmospheric scattering in the two models I've been developing. It's interesting to consider how the orange refracted sunlight merges in with the scattered (blue skylight) in the view from the moon. In most cases, the refracted sunlight is much brighter than the skylight, except they can be equivalent right in the lowest 2km or so above the Earth's limb. Another point of reference is that when we are in the center of the umbra the ring of sunlight extends up to 4km above the limb. Clouds will completely break the red ring in various places. When we are a bit off from the umbral center, then this ring has a variable thickness going above and below the 4km value.

Now with my more general "allsky" model I'm generating some views of an eclipse from the moon. The full view animation catches most of the total phase with some recent improvements. This includes some actual model clouds (for an arbitrary time) with the Earth's rotation bringing various clouds into view resulting in the shifting breaks in the red ring.

Here is a

The scattered light of the blue sky is barely visible given the "exposure" settings that are designed to show the sun without washing out its colors, though the animated GIFs introduce artifacts masking the sky. In the faint blue counts are a good test of monitor contrast and calibration. Brightness is displayed in a linear fashion, though the "exposure" changes with each frame. Might be nice to have a display utility allowing one to easily adjust the displayed brightness from 16-bit images. That would be one way to show the HDR without changing the inherent brightness relationships.

Posted by: scalbers Dec 26 2016, 02:52 PM

Below is a cropped view of an 8K animation zooming in along the Earth's limb at a scale of 1.6km per pixel, rotated 90 degrees clockwise. The first frame has the apparent sun about 45km off the limb (true sun 28km) though we're still technically in the umbra here. The edge of the umbra happens when the sun is about 85km up by the most widely used definition. We can see the sun is bright at the top where there is little extinction in the upper stratosphere. Below that is a blue layer due to ozone absorption in the lower stratosphere. The lowest part of the sun is red due to Rayleigh scattering in the lower troposphere just above the Earth's surface. The slight reddening effect of solar limb darkening isn't yet included in this model.

Here (click image below) is an animated crop of a 16K version that zooms in closer at 800m per pixel. The time lapse frames step every minute. The viewport shifts around the circumference of the Earth during the 3 hour period. The breaks in the ring shift noticeably even on the 1 minute time scale. This is caused by individual clouds that can be seen rising and falling in response to the Earths' rotation as if we're looking at the edge of a merry-go-round. Would be mesmerizing to see these shifting red arcs in reality.

This is a If you were actually on the moon looking through a telescope a solar filter would be advisable with a neutral density of about 2, except around 4.5 in the beginning. The upper limb of the apparent (refracted) sun slowly sinks as the actual solar limb goes farther down below the Earth's limb. Between the first 2 frames of the animation, when the actual sun and Earth limb coincide, the apparent sun reaches around 35km off the limb. An alternate definition of the umbral edge (effective or notional eclipsing layer) would be when the angular velocity of the apparent sun is half the true angular velocity. By a rough calculation this happens when the true sun is about 34km up and the apparent is 47km. The velocities get within about 10% of each other when the respective limbs are 70km and 71km up. Here is a table of the actual and apparent values.

Actual Apparent
------ --------
74km 75km
65km 67km
55km 59km
42km 51km
26km 43km
0km 35km

And just for fun of a lunar eclipse seen from the Earth, along with a of all the simulations.

------------ (UPDATED DEC 28) -------------

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