The discussion centers on Olbers' Paradox, which questions why the night sky is dark despite the abundance of stars emitting light in all directions. Participants clarify that light travels in straight lines, and we only perceive photons that enter our eyes. The conversation highlights that the Cosmic Microwave Background (CMB) radiation, originating from the Surface of Last Scattering, contributes to the universe's light but is not visible to the human eye. Additionally, the James Webb Space Telescope operates in the shadow of Earth at Lagrange point L2, illustrating the complexities of light visibility in space.
PREREQUISITESAstronomers, astrophysicists, students of cosmology, and anyone interested in the fundamental principles of light and visibility in the universe.
Light (generally) travels in straight lines from its source.Joe30174 said:Because if stars are radiating light in every direction, shouldn't there be light all over? And we only see the light/photons that our eyes are receiving? Though there may be dark spots from where crests meet troughs? Or am I completely wrong and missing something?
There should be light coming from everywhere there's a star, yes, but that isn't all of the sky - have a look at the resolution section of the Wiki article linked by @phinds.Joe30174 said:Because if stars are radiating light in every direction, shouldn't there be light all over?
You are right. There is sunlight almost everywhere in the solar system and you just don't see it if you do not look into the Sun. That implies that space crafts in the inner solar system always need some kind of protection from the light. It is quite hard to have something in darkness in space. One of the rare examples is the James Webb Space Telescope which is placed in Earth Lagrange point L2 (in the shadow of Earth).Joe30174 said:Because if stars are radiating light in every direction, shouldn't there be light all over? And we only see the light/photons that our eyes are receiving? Though there may be dark spots from where crests meet troughs? Or am I completely wrong and missing something?
The solar system is permanently flooded with light from the Sun. But, unless that light scatters or reflects off something, we can't see it.Joe30174 said:Because if stars are radiating light in every direction, shouldn't there be light all over? And we only see the light/photons that our eyes are receiving? Though there may be dark spots from where crests meet troughs? Or am I completely wrong and missing something?
Ibix said:There should be light coming from everywhere there's a star, yes, but that isn't all of the sky - have a look at the resolution section of the Wiki article linked by @phinds.
It might help you to draw a diagram. Draw a point somewhere and draw straight arrows coming out from it in all directions. The arrows are light paths coming off a star. Put the tip of your finger on the page somewhere - that's an astronaut in space. Which directions are arrows that pass under your fingertip coming from? Every direction, or just from the direction to the st
That's how I was picturing it. I underatand what we see is the light coming "straight" from the source. But if we had a camera that instead of a normal lense receives photons, sends signals put to detect photons and made an image off of that, everything would be lit up?Ibix said:There should be light coming from everywhere there's a star, yes, but that isn't all of the sky - have a look at the resolution section of the Wiki article linked by @phinds.
It might help you to draw a diagram. Draw a point somewhere and draw straight arrows coming out from it in all directions. The arrows are light paths coming off a star. Put the tip of your finger on the page somewhere - that's an astronaut in space. Which directions are arrows that pass under your fingertip coming from? Every direction, or just from the direction to the star?
It's not possible to have signals (of what?) bouncing off photons! The only way to detect light is to absorb it.Joe30174 said:That's how I was picturing it. I underatand what we see is the light coming "straight" from the source. But if we had a camera that instead of a normal lense receives photons, sends signals put to detect photons and made an image off of that, everything would be lit up?
The CMB is NOT "from the Big Bang". It is from the Surface of Last Scattering which happened some 400,000 years after what I think you mean when you say "the Big Bang" (which, by the way, has nothing to do with the Big Bang Theory which does not include the singularity that I assume you are referring to).bbbl67 said:Also, a lot of the original light from the Big Bang, which is now called the Cosmic Microwave Background radiation, has stetched out to microwave frequencies, and our eyes don't see in microwave. If we did, then we'd see a lot of light constantly hitting us, especially at night.
Yes, yes, you're very clever, thank you.phinds said:The CMB is NOT "from the Big Bang". It is from the Surface of Last Scattering which happened some 400,000 years after what I think you mean when you say "the Big Bang" (which, by the way, has nothing to do with the Big Bang Theory which does not include the singularity that I assume you are referring to).
Interesting. I was confused at first, because it seems like solar panels would not work at L2, but it is far enough away from the Earth to still get some sunlight that makes it around the Earth (given the relative sizes and angles of the Sun and Earth).DrStupid said:One of the rare examples is the James Webb Space Telescope which is placed in Earth Lagrange point L2 (in the shadow of Earth).
Danged autocorrect! Plus my brain is getting olber!PeroK said:I guess you mean the Olbers' paradox?
Yeah, when typing on a computer, auto-correct is our worst enema.sophiecentaur said:Danged autocorrect! Plus my brain is getting olber!