The Boring Sky (Sun)

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Expand view Topic review: The Boring Sky (Sun)

Re: The Boring Sky (Sun)

by Cargo » Sun Jul 26, 2020 3:55 am

Yes, I think when I wrote that, I was thinking of the near Earth-Moon area. Where gold-visors are required when in Space looking towards the Sun.

Re: The Boring Sky (Sun)

by GaryN » Sat Jul 25, 2020 7:23 pm

Cargo:
Truly, for Humans, it's completely Black out there. The sun is just a pin prick, that will still burn your retinas off though.
That is not how it works. If you knew exactly where to look when you were in deep space it would not hurt your eyes to look directly at the Sun. You need to understand how a deep space Sun sensor works, and why the less dense the interstellar medium the more difficult it is to be able to 'decode' the EM radiation emanating from distant sources. Similarly, the star trackers needed for space navigation become more expensive the further out you want to go, but you could only buy a star tracker capable of deep space navigation (if you could even afford one, and you need at least 3) from companies who are corporate arms of the military industrial complex. And they would want to know a great deal about you and your intentions, and then still might not sell to you.

In trying to find any information about surface light levels on Mars I found this pdf, and though there are still no actual numbers, the effects of the light on surface observations are interesting.

The Martian Sky and Its Illumination of the Martian Surface
https://mars.nasa.gov/mgs/sci/fifthconf99/6127.pdf

Nothing much has been done to examine the lunar sky since 1973
The measurements of sky brightness on Lunokhod-2
http://adsabs.harvard.edu/full/1975Moon...14..123S

The unexpected brightness of the lunar sky was attributed to the scattering of sunlight by the fine lunar dust, but as there is no proof that the sun emits any visible light then the light must have been created by the atmospheric dust, and fluorescence of silica particles is an accepted and well utilised phenomena.
I believe The reason that NASA does not have a rover on the surface is that detailed observations of the true nature of the lunar lighting would destroy the solar constant model for one thing, and if a direct measurement of solar heat by a Pyrheliometer were to be performed it would be found to be very cool in comparison to expected levels. No good for solar concentrators to smelt lunar ore.
Interesting that the Russian rover was driven by remote control from Earth, the signal time delay is insignificant. So I'm wondering if Elon Musk would be game for putting a sensor loaded remote controlled Cybertruck on the surface. Wouldn't that be a hoot!

Re: The Boring Sky (Sun)

by Brent72 » Sat Jul 25, 2020 1:46 am

Cargo wrote:
Fri Jun 19, 2020 3:08 am
Truly, for Humans, it's completely Black out there. The sun is just a pin prick, that will still burn your retinas off though.
The space lense of the Earth atmosphere does some wonderful great things for us..
For us on Earth, looking out into the night sky, it's all just a massive light show. Put on just for us!

Re: The Boring Sky (Sun)

by paladin17 » Fri Jul 24, 2020 12:51 pm

Cargo wrote:
Fri Jul 24, 2020 2:47 am
in case you still weren't sure.
I got my answers already.

Re: The Boring Sky (Sun)

by Cargo » Fri Jul 24, 2020 2:47 am

Is it just that word? I thought you had a question, and Gary's response was very well. I only meant to point out the conjunction, in case you still weren't sure.

Re: The Boring Sky (Sun)

by paladin17 » Thu Jul 23, 2020 1:27 pm

Cargo wrote:
Thu Jul 23, 2020 4:46 am
Paladin, you remember the news from the last year or so, the Moon is actually inside what could be considered (in regards to sunlight), the Earth's atmosphere. In fact, it was just on the last page. https://thunderbolts.info/forum3/phpBB3 ... rt=15#p536
Yes. And the Solar System is inside the Sun's atmosphere, which is inside Galaxy's atmosphere.

Re: The Boring Sky (Sun)

by Cargo » Thu Jul 23, 2020 4:46 am

Paladin, you remember the news from the last year or so, the Moon is actually inside what could be considered (in regards to sunlight), the Earth's atmosphere. In fact, it was just on the last page. https://thunderbolts.info/forum3/phpBB3 ... rt=15#p536

Re: The Boring Sky (Sun)

by GaryN » Wed Jul 22, 2020 3:54 pm

Hey paladin17,
On the near side of the Moon the light is provided by Earthshine and is sufficient for safe surface operations to be carried out during the lunar night according to NASA. During near side daytime it is brighter because the solar ionising radiation is producing a full spectrum light by interaction with the sub-micron sized silica particles in the lunar atmosphere. We have no measured surface illumination levels of either the near or far side, but the far side day time illumination levels would be found to be much dimmer than the near side as the far side is never subject to the ionising radiation from the Van Allen belts and Earths upper atmosphere, which in effect bias the near side dust particles.

Lighting Constraints on Lunar Surface Operations (1991)
https://www.lpi.usra.edu/lunar/strategi ... raints.pdf

The only measured illumination levels I have seen so far are for the Earth taken when Apollo 8 was half way to the Moon, and was 310 Lumens. They did not do the same for the Moon but it was noted that the Moon was much dimmer, though that would be expected because of the lower lunar surface albedo. That we have no measured surface illumination levels for the Moon, or Mars or Mercury after all these years should raise some questions but nobody seems to notice or to care.

Re: The Boring Sky (Sun)

by paladin17 » Wed Jul 22, 2020 9:51 am

How could they see the surface of the Moon (or, in fact, anything else at all) if, as you claim, visible light is produced by the atmosphere?

Re: The Boring Sky (Sun)

by GaryN » Sun Jul 19, 2020 6:19 pm

Comet Neowise from the ISS.
https://scitechdaily.com/images/Comet-N ... 77x518.jpg

From the ISS the comet is only visible when looking through the atmosphere of course, and from Earth it is the same. From deep space the comet is not visible, and the Apollo astronauts who tried to photograph Bennets Comet failed. Mission control had some discussions and they had another go but no luck. So they thought about it some more and were about to make a 3rd attempt when those now famous words were issued,"Houston, we've had a problem". That was the end of the attempts to photograph the comet of course.

Before the first attempt they were given instructions.
031:57:02 Brand: Okay. The second one, at 32 hours looking at Bennett's Comet - we want the pictures taken when the spacecraft is as stable as it's going to be before starting PTC. The stability requirement is very high. We weren't sure if you understood that from what we passed up. In addition, the photographs might not show as much as the eye can see of the comet, so if you see anything interesting about the structure of the comet, why, sketching it is in order and is encouraged. Over.
They couldn't sketch what they couldn't see of course. They informed Command that they could not see the comet, or stars, through the sextant or the Optical Alignment telescope, or by eye, but Command was determined they get some photos one way or another. They never did.

One interesting sighting though as they were approaching the Moon was of 2 shadowy shapes not far away from the spacecraft that they could not figure out. Probably their chaperones standing by to help them get home safe and sound.

Re: The Boring Sky (Sun)

by GaryN » Sun Jun 21, 2020 8:06 pm

At 16:55 in this youtube video the solar neutrino problem is discussed and the EU gets a mention as being able to provide a possible alternative for the discrepancy in detected neutrino counts.

Solar Neutrinos
https://youtu.be/8M_K5ytfsPk?t=1016

In my model neutrinos are produced in an electron-positron annihilation process which is the reverse of the electron and positron creation process by way of two photon physics. I have absolutely no idea if this would produce a closer match to measured counts.

Also see "Solar Neutrinos in the Electric Universe | Space News"

Re: The Boring Sky (Sun)

by Cargo » Fri Jun 19, 2020 3:08 am

Truly, for Humans, it's completely Black out there. The sun is just a pin prick, that will still burn your retinas off though.
The space lense of the Earth atmosphere does some wonderful great things for us..

Re: The Boring Sky (Sun)

by GaryN » Wed Jun 17, 2020 6:15 am

"The star-field images are 10's of seconds long. The longest exposure done was an early look for Bennu, and was 2 hours long."

So your eyes would see nothing, we have no ability to store electrons as do the sensors used in these instruments. Looking at any raw data files available for many of the instruments you find a calibration file with each image, and each pixel of the sensor has its own calibration figures, the full well capacity being one of them. This is why when you download a raw image it can be gigabytes in size whereas an ordinary camera file size is far less than that, even a 20 MP camera would only be 30 megs or so. Their cameras are only 5 MP.

Re: The Boring Sky (Sun)

by Cargo » Wed Jun 17, 2020 1:47 am

More tidbits from design and testing.
The near-Earth asteroid Bennu is fully as dark as the nucleus of comets such as 1P/Halley,
81P/Wild, 19P/Borrelly, or 103P/Hartley and of asteroids such as 253 Mathilde (Hergenrother et
al. 2013). ...disparity between noontime observations at the equator at
perihelion and near-terminator observations at aphelion that can be 3 orders of magnitude (Takir
et al. 2015), 2 orders of magnitude from the reflectance itself and 1 order of magnitude due to the
cosine effect itself. This large dynamic range is accommodated by combining a wide dynamic
range detector with exposure times ranging from millisecond to tens of seconds
typical signal levels for laboratory light (e.g., the illumination level inside
of the Lockheed Martin high-bay where the OCAMS imagers were integrated onto the
spacecraft) are 6000 DN (data number) for a 100 ms SamCam exposure. The high-bay was
measured to have an illuminance of 160 lux, corresponding to 0.51 Wm–2 sr–1, assuming a typical
luminous efficacy of 100 lm/W. Bennu’s surface is somewhat brighter under the Sun’s full
illumination at 1 AU, with an estimated illuminance level around 410 lux and a radiance of 1.4
W m–2 sr–1 at 65° incidence and 0° emission requiring a 40 ms SamCam exposure to generate a
peak signal level of 6000 DN
The star-field images are 10's of seconds long. The longest exposure done was an early look for Bennu, and was 2 hours long.
https://i.pinimg.com/236x/b7/0b/09/b70b ... 74719d.jpg
the first images of its target asteroid Bennu from a distance of 1.4 million miles
The circle is Bennu.

Re: The Boring Sky (Sun)

by GaryN » Tue Jun 16, 2020 9:32 pm

MapCam Star-Field
Here is an image from the MapCam during Earth based testing for comparison.
http://www3.telus.net/myworld/mapcam.png

Can it take such an image from space?

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