Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: bearnard1212 on 09/02/2021 13:44:49
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How to apply the red-shifting-of-light explanation of the darkness of the sky to the space between the Earth and the Moon: we see this area dark though the Sun's light travels through it?
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Well, it doesn't appear dark because the moon is there. It's the brightest spot in the night sky. Maybe we should look off to the side somewhat, no?
You seem to be imagining a beam of light being viewed from the side so to speak, or at least I get that from the second half of your post where you talk about the sun's light going between Earth and moon. A beam of light might become somewhat visible if there is dust or something to intercept and deflect a portion of it, but a given photon not directed at Earth cannot be detected from Earth. It can be measured only in one place. At best it is measured at the speck of dust and perhaps a new photon is emitted from there that happens to be detected by you.
I have no idea how you think red-shifting comes into play here. Neither the sun nor the moon is particularly receding from Earth to the point where light from it is significantly red shifted. Red shifting is from objects with significantly high recession velocities, which pretty much confines it to objects not in our galaxy.
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Well, it doesn't appear dark because the moon is there. It's the brightest spot in the night sky. Maybe we should look off to the side somewhat, no?
You seem to be imagining a beam of light being viewed from the side so to speak, or at least I get that from the second half of your post where you talk about the sun's light going between Earth and moon. A beam of light might become somewhat visible if there is dust or something to intercept and deflect a portion of it, but a given photon not directed at Earth cannot be detected from Earth. It can be measured only in one place. At best it is measured at the speck of dust and perhaps a new photon is emitted from there that happens to be detected by you.
I have no idea how you think red-shifting comes into play here. Neither the sun nor the moon is particularly receding from Earth to the point where light from it is significantly red shifted. Red shifting is from objects with significantly high recession velocities, which pretty much confines it to objects not in our galaxy.
I found that you you don't actually need red shifting to explain this. You perceive something as bright when it reflects or transmits visible light towards your eyes. In space there is nothing to reflect light towards your eyes (unlike the atmosphere where there is air, dust, etc) so sunlight passes through without interacting.
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You perceive something as bright when it reflects or transmits visible light towards your eyes. In space there is nothing to reflect light towards your eyes (unlike the atmosphere where there is air, dust, etc) so sunlight passes through without interacting.
exactly
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Well, it doesn't appear dark because the moon is there. It's the brightest spot in the night sky. Maybe we should look off to the side somewhat, no?
You seem to be imagining a beam of light being viewed from the side so to speak, or at least I get that from the second half of your post where you talk about the sun's light going between Earth and moon. A beam of light might become somewhat visible if there is dust or something to intercept and deflect a portion of it, but a given photon not directed at Earth cannot be detected from Earth. It can be measured only in one place. At best it is measured at the speck of dust and perhaps a new photon is emitted from there that happens to be detected by you.
I have no idea how you think red-shifting comes into play here. Neither the sun nor the moon is particularly receding from Earth to the point where light from it is significantly red shifted. Red shifting is from objects with significantly high recession velocities, which pretty much confines it to objects not in our galaxy.
I wonder, weather it can be observed with a usage of satellites, micrasatellites or guided or unguided light-class launch vehicle designed for microgravity missions? Thus, I guess we get more correct information
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How to apply the red-shifting-of-light explanation of the darkness of the sky to the space between the Earth and the Moon: we see this area dark though the Sun's light travels through it?
Could it be due to "Dark Matter". Current theory suggests that most of the Universe consists of this "Dark Matter".
If that is true, the Solar System must be full of DM. Mightn't its presence account for some anomalies in our observations of the Moon?
For example, why the Moon sometimes has a reddish colour during a lunar eclipse, instead of disappearing from view entirely.
Explanations of this as due to refractive effects in the Earth's atmosphere, don't seem entirely convincing.
Suppose instead, there are varying amounts of DM between the Earth and Moon. One might expect such variations, and they might cause colour changes in transmitted light between the two bodies.
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Could it be due to "Dark Matter".
No
Because the defining property of dark matter is that it doesn't interact with EM radiation.
There's a hint in the name.
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Explanations of this as due to refractive effects in the Earth's atmosphere, don't seem entirely convincing.
I wasn't aware anyone would have tried. The blood moon effect is due to scattering.
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How to apply the red-shifting-of-light explanation of the darkness of the sky to the space between the Earth and the Moon: we see this area dark though the Sun's light travels through it?
Could it be due to "Dark Matter". Current theory suggests that most of the Universe consists of this "Dark Matter".
If that is true, the Solar System must be full of DM. Mightn't its presence account for some anomalies in our observations of the Moon?
For example, why the Moon sometimes has a reddish colour during a lunar eclipse, instead of disappearing from view entirely.
Explanations of this as due to refractive effects in the Earth's atmosphere, don't seem entirely convincing.
Suppose instead, there are varying amounts of DM between the Earth and Moon. One might expect such variations, and they might cause colour changes in transmitted light between the two bodies.
The total estimated amount of dark matter contained within the Solar system is the equivalent to the mass of a single small asteroid.
Do not be misled by the fact that dark matter is expected to make up most of the matter in the universe as a whole. It is a matter of relative densities. As empty as it seems to us, the solar system is extremely more compact and dense that the visible part of galaxy as a whole,( if you took all the mass in the solar system, spreading out evenly over its volume, and then did the same with a volume of 100 light years in radius in a representative part of the galaxy as the solar system is in, taking into account all the stars, etc in that volume, and compared the density of the two, the first volume would be many, many many times more dense than the second). In addition, the majority of dark matter for our galaxy is in that part of a spherical volume that lay outside of the visible disk of the galaxy.
So, if you take the total galactic dark matter, spread out over its spherical volume, the amount expected to be found within the volume of the solar system is quite small.
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Explanations of this as due to refractive effects in the Earth's atmosphere, don't seem entirely convincing.
I wasn't aware anyone would have tried. The blood moon effect is due to scattering.
Isn't "scattering" another word for "refraction"?
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Explanations of this as due to refractive effects in the Earth's atmosphere, don't seem entirely convincing.
I wasn't aware anyone would have tried. The blood moon effect is due to scattering.
Isn't "scattering" another word for "refraction"?
No. Refraction is caused by light passing form crossing through a surface that defines two regions with different light propagation speeds ( like when passes from air to glass and back to air again.
Scattering is caused by the light interacting with individual particles as it passes though a medium.
Here are 4 cubes, two large and two small.
The left ones show refraction and the left ones scattering.
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With the refraction cubes, the size doesn't effect the refraction, just the angle the light passes through the faces.
With the scattering cubes, the volume effects the scatter, the larger cube scatters more light because the light has to pass through a larger volume.