The Sun

[WesBrew]

A nice burn got me thinking about the sun. It seems simple, big flaming ball at the center of the solar system. We see it every day, no big deal. Looking a little deeper, it's not burning fuel as most would assume but that it is Nuclear Fusion of hydrogen and helium.
A few years back, someone who claimed to work with NASA told me that there is no visible light from the sun, that its radiation that interacts with our atmosphere. He said that from space you can't see the sun at all. Black, like the photos you see from space missions, nothing in the background. There was some beer involved, I didn't believe it.
Any Heliophysicists in here?

-link to national geographic short video on the sun, on youtube.

 

[lumpher]

That person was confusing solar wind with solar light. There is a difference. The atmosphere does diffuse the Sun's light and cause it to appear yellow (Rayleigh's Scattering of Light); it's white from space. There are many thousands of actual pictures of stars from space with no special filters; just filters to darken the light that person does not believe in. Here is a good article on it:
https://universemagazine.com/en/why-are-the-stars-not-visible-in-space-photos/

 

[Hoochin'Fool]

That person might have worked at NASA, probably washing dishes in the employee cafeteria...

 

[WesBrew]

Probably a beer theory. Ive actually heard it more than once though.

 

[DBhomebrew]

Psst... light is radiation. The same stuff as x-rays and gamma rays, etc.

Maybe your NASA employed friend is also an art history enthusiast? 'Light' as in the stuff Vermeer is famous for? True, that stuff is atmosphere being brought to luminescence by the sun's radiation.

Still, it's the atmosphere that's missing in space, not visible light. The radiation in the visible band is still there, flowing freely and invisibly past the astronaut, but there's no atmosphere to bring it into view.

 

[WesBrew]

That sounds similar to the guy sitting next to me at a bars point. So if one were in space, no atmosphere, could they not see the sun or just not the radiation emitted from the sun?

 

[DBhomebrew]

As the photo above shows, you see the source, the sun. It's the radiation which is only revealed when it reflects off something into our eyes.

A radio station (the sun) with its tower (source) is always visible. Its transmission (radiation) is only revealed (seen) when you have a radio (atmosphere, stuff) tuned to its station (eyes evolved to sense that particular wavelength).

 

[mac_1103]

Psst... light is radiation. The same stuff as x-rays and gamma rays, etc.

Well yes and no...

So if one were in space, no atmosphere, could they not see the sun or just not the radiation emitted from the sun?

You see the sun. You see light on surfaces that the sun shines onto and reflects off of. What you don't see is a lit up sky, because, well, there's no sky.

 

[DBhomebrew]

Well yes and no...

Lions and oak trees are both carbon-based sponges full of water. They're both the same stuff, but clearly not the same thing.

 

[mac_1103]

Apples and oranges OTOH...

 

[DBhomebrew]

Pilners and stouts. Same stuff.

 

[betarhoalphadelta]

That sounds similar to the guy sitting next to me at a bars point. So if one were in space, no atmosphere, could they not see the sun or just not the radiation emitted from the sun?

I think the ultimate idea here is probably that there's no true "physics" definition of "visible light". It's merely radiation that our eyes have evolved to "see". There might be intergalactic aliens who can "see" wavelengths in the X-ray band that are invisible to us, but for whom the entire radiation spectrum we call "visible light" our eyes can detect would be invisible, or "dark".

"Visible light" is purely a human construct. If our eyes evolved differently we'd possibly consider a completely different spectrum of wavelengths to be "visible light".

Either way, if you were in space, your eyes would still be able to detect that same radiation as visible light. There would be atmosphere in your space suit and obviously some level of "atmosphere" inside your eyeballs. If there wasn't, you'd have bigger issues to worry about than what you see.

 

[sibelman]

there is no visible light from the sun,

Simply put, this is false. No atmosphere needed - except to keep you alive while being blinded by that bright light.

 

[DBhomebrew]

"Is a radio wave the same as a gamma ray?

"Are radio waves completely different physical objects than gamma-rays? They are produced in different processes and are detected in different ways, but they are not fundamentally different. Radio waves, gamma-rays, visible light, and all the other parts of the electromagnetic spectrum are electromagnetic radiation.

"Electromagnetic radiation can be described in terms of a stream of mass-less particles, called photons, each traveling in a wave-like pattern at the speed of light. Each photon contains a certain amount of energy. The different types of radiation are defined by the the amount of energy found in the photons. Radio waves have photons with low energies, microwave photons have a little more energy than radio waves, infrared photons have still more, then visible, ultraviolet, X-rays, and, the most energetic of all, gamma-rays."

- A supposed employee at NASA

https://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.html

 

[Clint Yeastwood]

When I was a kid, I used to stare at the sun until it seemed to change from yellow to blue and back, repeatedly. I didn't know any better. Later in life, I saw various sources claiming this was extremely harmful to the retinas and that it would cause blindness. I went on to have better than 20/20 vision, so I can only imagine how great my vision would have been had I not stared at the sun. I guess I would have been able to see through walls. As it was, I was able to see Jupiter's moons without a telescope, until old age hit and I started bumping into walls.

I mentioned it to a buddy of mine, and he said he had done the same thing, and he also had excellent vision until he got old.

What is myth and what is truth? Never easy to say, especially now that we live in a world where British schoolkids can claim they're cats and the other kids get in trouble if they disagree.

 

[ehall]

the atmosphere is really nice in here. I think I'll stick around a while...