All hail the blue green Sun God!

November 14, 2013 6:15 AM

13 Facts About Space That Will Make Your Head Explode. [SLCrackedVideo | Disclaimer: will not make your head explode. But is still interesting!]
posted by quin (25 comments total)

Just because the sun's emissions peak in the blue-green part of the spectrum doesn't mean it can be described as being blue-green -- it's so bright across a wide variety of colors that it is white. The color used to represent it in art / illustration is more a cultural convention than actual perception.

Also, have cosmologists downsized the Milky Way in recent years? I always think of the MW as having 400 billion stars, not 300. I suppose all such figures are guestimates. That, or I am taking a Cracked video too seriously.
posted by aught at 6:53 AM on November 14, 2013 [1 favorite]

Nit-pick time! The Sun might have a blackbody spectrum (the continuum of photons of various energies that would be emitted by a perfect thermal emitter) that peaks in the blue-green, but even without the atmosphere scattering blue preferentially, we will never see it as blue-green, because the way our eyes process color. It turns out that a blackbody spectrum that peaks in the green wavelengths has too many photons of other wavelengths in it, in particular the red wavelengths, and too few blue photons, so the combinations of cones in our eyes will see that as yellow, not green. To see green, you need a spectrum that peaks more sharply in the green wavelengths than is possible with a blackbody spectrum. If we evolved with different sets of cones that have a different chemical reactions to various wavelengths of light (as other species did), we would define blackbody colors differently. This is why people will talk about red-hot fires, or white-hot fires, but never green-hot. If a fire is burning green, it's because someone threw some chemical in there to get a non-blackbody spectrum.

Also, as a personal preference, I define "now" as events that occur on my past-light cone. So when I see Betelgeuse go supernova, I'll say that it happened "now" even though in another foliation of space-time, it happened 600 years ago. It's just much less confusing that way, and unless someone develops faster-than-light travel, is 100% unambiguous. I also check the sky every winter night I can just to see if Betelgeuse has blown up yet. I hope it happens in my lifetime, and not, you know, 100,000 years from now.

Though these nitpicks shouldn't be taken to say that I didn't enjoy the video.
posted by physicsmatt at 6:57 AM on November 14, 2013 [26 favorites]

Well it's a good thing it did make my head exploNO CARRIER
posted by eriko at 7:01 AM on November 14, 2013 [2 favorites]

Some of that was pretty silly and annoying but I for one do have an exploding head sensation when I try to get a handle on the incredible size of the universe. I mean the number of stars is actually bigger than the national debt!
posted by sammyo at 7:02 AM on November 14, 2013

aught, I don't actually know about the changing number of stars estimated to be in the Milky Way, but the mass of the Milky Way's dark matter halo has recently been a subject of much discussion, with estimates ranging from ~8 x 10^11 to 2 x 10^12 solar masses. It's actually very difficult to get accurate measurements of our own Galaxy sometimes, since we're in the middle of it. We have a much better vantage point to look at something like Andromeda, for example, whereas we have no idea what's in the disk past the local spiral arms, much less the other side of our own Galactic bulge. All we can do is extrapolate from what we can see locally, and what other spiral galaxies look like.
posted by physicsmatt at 7:24 AM on November 14, 2013

This video LITERALLY sucked my spaceballs.
posted by ReeMonster at 7:52 AM on November 14, 2013

The next time your younger sibling is drowning, just throw Saturn at them.

I know the mix of facts and fluff in the video is supposed to be funny, but sadly I am just more confused.
posted by warm_planet at 7:55 AM on November 14, 2013

The next time your younger sibling is drowning, just throw Saturn at them.

I know the mix of facts and fluff in the video is supposed to be funny, but sadly I am just more confused.

If the surreal and ridiculous imagery were extended, I couldn't help think how the very dense core of Saturn would fall out of the surrounding hydrogren/helium/gases and crush to sibling. (The popular factoid of Saturn being "less dense than water so it would float in the tub!" - which I have been hearing for decades - has always irritated me, I guess, in its pandering nonsensicality.)
posted by aught at 8:15 AM on November 14, 2013 [3 favorites]

It might be worth using noscript on Cracked these days, btw. The update says they've fixed the latest malware issue, but it sounds like it's a recurring problem with them. (fwiw, I've never had any issues even without extra protection visiting Cracked, but that could just be luck)
posted by jason_steakums at 8:17 AM on November 14, 2013 [1 favorite]

Do you have stairs in your house?

I fear the Terrible Secret of Space is now older than most Cracked writers. It's definitely funnier.
posted by Nelson at 8:17 AM on November 14, 2013

physicsmatt: "Also, as a personal preference, I define "now" as events that occur on my past-light cone. So when I see Betelgeuse go supernova, I'll say that it happened "now" even though in another foliation of space-time, it happened 600 years ago. It's just much less confusing that way, and unless someone develops faster-than-light travel, is 100% unambiguous. I also check the sky every winter night I can just to see if Betelgeuse has blown up yet. I hope it happens in my lifetime, and not, you know, 100,000 years from now."

It's not just personal preference; under both quantum physics and General Relativity there is no such thing as "simultaneity", and objects that occurred c*deltaT aware are happening "now", as far as any discernable result in the universe can prove.

Your past-light cone is really the only valid way to describe the universe; distance and time are inseparably interlinked.

EDIT: And... I just realized I softballed physics at physicsmatt, d'oh! But, it'll stand for others to read.
posted by IAmBroom at 8:55 AM on November 14, 2013 [1 favorite]

I am certainly in no mood to have my head explode today; thank you but NO thank you!
posted by grubi at 9:01 AM on November 14, 2013 [2 favorites]

The sun is not any colour, in the sense that it "is yellow" or "is blue-green". Nothing is any colour in particular. Things just appear that way.

The sun s throwing out a spectrum of electromagnetic frequencies - and lots of them - some of which can be perceived by our eyes under certain circumstances. What "colour" the sun is depends entirely on those circumstances and the way our visual system chooses to interpret them.

If you look at a "red" apple in light that lacks any of the longer visible wavelengths, it will most certainly not be red. And even that's not as simple as it sounds, as the eye is quite capable of adjusting colours of items in the visual field depending on what it sees in adjacent areas, not just on incident/reflected/transmitted photon frequency.

However,it takes much longer to say all that than "The sun isn't yellow, it's blue-green".
posted by Devonian at 9:11 AM on November 14, 2013 [2 favorites]

I read Cracked fairly regularly, but I've never watched any Cracked videos before. Read aloud, the Cracked "style" is really grating. It's interesting, as most of the time I hear about how much tone is lost in the written word vs. oral communication, and while I don't agree that's always true, in this case it's actually a *good* thing. Because yeesh.
posted by Uther Bentrazor at 9:13 AM on November 14, 2013 [1 favorite]

I always thought sunlight was white, but as any trip to the paint store will tell you, there are many different whites. Calling it blue-green is stretching things.
As for it appearing yellow, isn't that due to the fact that much of the blue light is scattered by the atmosphere so the resulting direct light is (white - blue) = yellow?
posted by rocket88 at 9:33 AM on November 14, 2013

I have it on good authority that the Sun isn't yellow, it's chicken.
posted by Kirth Gerson at 10:07 AM on November 14, 2013 [6 favorites]

I sort of like being aware of the light-cone effect. What you see--it isn't there anymore. Knowing that helps keep my terracentrism under control, and lets me feel good about detesting daylight savings time.
posted by mule98J at 10:20 AM on November 14, 2013

Just being in space makes my head explode. And the rest of my body!
posted by Bunny Ultramod at 10:37 AM on November 14, 2013

I read Cracked fairly regularly, but I've never watched any Cracked videos before. Read aloud, the Cracked "style" is really grating. It's interesting, as most of the time I hear about how much tone is lost in the written word vs. oral communication, and while I don't agree that's always true, in this case it's actually a *good* thing. Because yeesh.

Somehow all the room noise in the recording really augments this effect.
posted by invitapriore at 10:38 AM on November 14, 2013

"Space, is big. Really big. You just won't believe how vastly, hugely, mindbogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space!"

(If that was posted in the article, don't flame me-- I didn't read it.)
posted by entropicamericana at 10:38 AM on November 14, 2013

It turns out that a blackbody spectrum that peaks in the green wavelengths has too many photons of other wavelengths in it, in particular the red wavelengths, and too few blue photons, so the combinations of cones in our eyes will see that as yellow, not green. To see green, you need a spectrum that peaks more sharply in the green wavelengths than is possible with a blackbody spectrum.

Beautifully put, and makes it all the more surprising that higher plants spit back the meat and only nibble away at the meager bread on either side, especially since a more efficient absorber seems to have evolved first.
posted by jamjam at 11:09 AM on November 14, 2013 [2 favorites]

somewhat related in that it's about space and about (not) exploding heads and about the sun: what would happen if you were tossed into the vacuum of outer space unprotected without a suit during a typical manned mission (in terms of distance from the sun):

http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970603.html

Turns out: not all that much and, yes, you could totally survive without much permanent damage if it's for less than half a minute.

You do not explode (your skin is strong enough to withstand internal pressure)
Your blood does not boil (it's sealed off from the vacuum by your skin etc)
You do not freeze (space is cold but heat transfer is slow when all you can do is radiate it away - related to the fact that the problem with constructing spaceships is cooling, not heating)

If your mouth is open the saliva on your tongue will boil off.
If you're not in the shade of something you'll get one hell of a sunburn.
posted by Hairy Lobster at 12:42 PM on November 14, 2013 [1 favorite]

A thing I can't get my head around is the fact that the Andromeda galaxy is inclined to our viewpoint and is so huge that the light from far side is 70,000 light years older than the light from the near side.
posted by bonobothegreat at 10:58 PM on November 14, 2013

jamjam: "
Beautifully put, and makes it all the more surprising that higher plants spit back the meat and only nibble away at the meager bread on either side, especially since a more efficient absorber seems to have evolved first."

Perhaps those life forms were crowded out in the first (known) Great Extinction Event, when oxygen appeared. Cyanobacteria were around with the now-common photosynthesis mechanisms, but I'm not clear on how much archaeae there were around then.

O2 is a pretty damned corrosive gas, after all. And evolution is not a path to the "smartest" or "best" constructions; it selects for "best-available right now, out of this immediately available group".
posted by IAmBroom at 12:17 PM on November 15, 2013

Nit-pick time! The Sun might have a blackbody spectrum (the continuum of photons of various energies that would be emitted by a perfect thermal emitter) that peaks in the blue-green, but even without the atmosphere scattering blue preferentially, we will never see it as blue-green, because the way our eyes process color. It turns out that a blackbody spectrum that peaks in the green wavelengths has too many photons of other wavelengths in it, in particular the red wavelengths, and too few blue photons, so the combinations of cones in our eyes will see that as yellow, not green.

Of course it is not just the cones in our eyes that determine how we see color, there are a number of different regions of the brain that affect color vision and somehow "bind" together to create the unified visual experiences we have.

This is a fascinating article:

The neurological basis of conscious color perception in a blind patient

Evidence suggests that a first stage of color processing in areas V1 and V2 is concerned mainly with registering the presence and intensity of different wavelengths and with wavelength differencing; a second stage, located in area V4, is concerned with automatic color constancy operations (21); and a third stage, based on the inferior temporal and frontal cortex, is more concerned with object colors (15). Lesions restricted to V4 lead to a specific loss of conscious color vision (cerebral achromatopsia). Although color blind, achromatopsic patients can discriminate between different wavelengths (22) but cannot attribute colors to them. Whether chromatic cues guide the behavior of cerebral achromatopsics in a covert fashion, without any conscious accompaniment, is still an open question (23).

So patients with small lesions localized to V4 can lose color consciousness even though their eyes and the rest of their vision system are intact.

And amazingly, there are a few patients with massive damage to their vision system, who are essentially blind, but who remain conscious of colors. In this case the patient does not process a wide band light spectrum normally, the colors experienced are much more wavelength based, whereas it is much more complicated in a "normal" brain where the color of one object in a visual field is affected by surrounding objects, past objects, and other stuff.

The results of the color constancy tests (Tables 3 and 4) show that PB’s color vision is very much wavelength-dominated, because he is correct in his identification when the color on the TV monitor was generated by a single phosphor or when the Color Aid papers were made to reflect a great excess of one wavelength over the others. Thus, he reported a green patch as green when it reflected a lot more middle wave (green) light. But when it was made to reflect more long-wave (red) light and still looked green to normal observers, because of the operation of the color constancy mechanism in them, PB usually reported it to be white (as would normals viewing it in the void mode) or red or brown. This is what would be expected if his color vision were wavelength-based and his color constancy mechanisms defective.

That the color vision is fully conscious is made clear by the patient’s introspective reports, which consistently correspond to, and are felt to stem from, a phenomenal awareness of the visual input, rather than being mere guesses produced in reaction to “unseen” stimuli. Stated briefly, when PB says, “I see red, or blue, etc.,” when presented with a colored stimulus, to all appearances he seems to be sharing a phenomenal experience of color with normal observers. A fair-to-good conscious color perception coupled to poor form vision has been reported in brain-damaged patients, but other visual abilities, including a fully preserved visual field and good visual acuity, are commonly quite normal in them. By contrast, PB not only systematically fails in tests of shape perception but is also perimetrically blind and lacks any visual acuity, thus qualifying as an indisputable case of long-standing cortical blindness.

posted by Golden Eternity at 10:55 PM on November 16, 2013 [2 favorites]