Neil deGrasse Tyson Explains the REAL Color of the Sun

[Music] welcome to the explainer zone yes the explainer itself yeah yeah not the twilight zone that's the twilight zone we're confused at the end right the explainer zone where you come out knowing more than you get when you win some stuff right and so i think there's no end to this just so you know good i will i'll be calling you forever all right so i want to talk about the sun the color of the sun okay all right well you know me i don't see color you don't see color sorry we're already done here so so so here's the thing if you're a schoolchild and you to draw a scene and you want to put the sun in the sky what crayon do you reach for um well i was a very depressed child so black black uh okay no you knew about black holes but yeah exactly no oh it's always a big yellow it's always yellow and this is this notion has been with us since childhood that the sun is yellow yes and that's not true it's not even close to being true uh-oh and so yeah i'm sorry you know i don't want to are you saying that are there any kids watching please uh you might want to leave the room right now because we're not sure if there's a crayola available for you to draw your little scenes with the house and the grass okay so here's the thing the sun in broad daylight is too bright to look at all right without risking damaging your eyes so unless of course you have perfect eyes so so you don't do it all right so when is the time most people ever find themselves looking directly at the sun when is that well the only times i've ever done it is sunset and sunrise sunday exactly exactly so not only do we have the yellow crayon in our crayon box from childhood anytime we actually ever find ourselves looking at the sun either on purpose or by accident it's low on the horizon the sun is rising or setting and it has a deep yellow color sometimes it's so deep it can be red amber into red yeah so and we know the sun isn't red of course it's not red we know that's this isn't krypton it's not krypton exactly what they're red sun so you you know intuitively it's not red but somehow you don't know intuitively that it's also not yellow okay what color is the sun it is white now now come on man why you gotta do that white see what what just like everything else all of a sudden chuck not everything we got commentary you know what seriously we gotta must we whitewash all of history including the sun really so yeah so it's not yellow okay it's not yellow now i can give you evidence of this if you need evidence but i'm simply saying that as the sun gets let's look at earth and and there's the atmosphere wrapped around the earth if the sun is directly overhead or anywhere near directly overhead it goes to sort of let's call that one thickness of atmosphere okay top to bottom as the sun gets lower and lower in the sky the path of light through the atmosphere is longer okay because now you got there's that angle through it and the lower the sun gets on the sky the more and more atmosphere it has to pass through and in fact you can calculate how many equivalent atmospheres it went through okay and you just need a little bit of trigonometry it's a simple calculation and if it's low on the horizon it goes through five six ten equivalent atmospheres gotcha when it's low on the horizon so whatever the atmosphere is doing to the sun when it's high up overhead it's doing it ten times that and more when it goes lower on the horizon okay okay so let's see what the atmosphere is doing when the sun is overhead um in comes white light okay and [Music] white light is composed of colors as isaac newton demonstrated all the colors of the rainbow red orange yellow green blue indigo if you must violence violet okay so in it comes particles in earth's atmosphere that happen to be the same size as the wavelength of light of the blue side of the spectrum the blue indigo purple violet side of the spectrum those particles preferentially scatter the blue [Music] out of the sunlight preferentially scatters it so it subtracts away a little bit just a little bit all right the rest of the light makes it all the way to earth's surface but some of the blue gets scattered and that's why we have a blue sky nice the blue sky is stolen sunlight that would have otherwise passed straight through look at that okay right because the sky is really clear right okay so now watch how beautiful is that though now let's have the sun get a little lower in the sky well there'll be more of this going on okay more of the sky that's why on cloudless days into sunset the sun gets deeper and deeper and deeper blue the bluest sky that's why sky blue is light blue right all right you want to talk about sirius right home to mama blue is the blue sky that surrounds the twilight curtain of a sunset now you're talking blue right okay so so much blue is taken out that we now roy g biv red orange yellow green blue and he took out blue indigo violet what's left red orange yellow green okay if you add those colors together you're gonna get an amber sun and depending on how how many particles there are you'll get a red sun or you'll get a simple yellow sun right on the horizon and so you now look at so oh we have a yellow star look it's yellow oh no it's the atmosphere made it yellow okay it's lying to you and if you so here's what you do broad daylight if there's thin cirrus clouds okay so it's safer to look up to the sun look up the sun in the middle of the day is it yellow no no it is white this is very disturbing this is very very disturbing because the clouds themselves don't change the color of the sun it'll just it just dims it so you look at a slightly dimmer sun uh behind the cl thin clouds as they pass it's not yellow not only that consider the following all right now this takes a little extra thinking put your thinking cap on okay and we in another explainer we addressed this but now there's a different reason for it if i have a sheet of paper and it's white that means light reflected of it from it is an even mixture an equal mixture of red orange yellow green blue violet all those colors together in optics makes white don't tell this to an artist right it doesn't it doesn't work on the ease no it's they you do it's just the opposite in all right it's just the opposite you don't get black but you'll get like slush you'll get sludge right all right so the fact that the page is white means all of those colors of light are hitting that page so that when they reflect up you see white okay so a white light illuminating a white piece of paper shows up to you as a white piece of paper there you go okay now white reflects all colors let me put a a red gel in front of the light now look at the paper what color is it it's red it's red kind of pinkish but yeah that's right so it reflects all colors but now it's only getting red it's going to reflect the red it reflects all colors the page is red right your eye okay let's put a blue gel what happens to the page the page is blue same thing yeah okay so if the sun were yellow then snow would be yellow yellow which by the way sometimes snow is yellow and it's not from the sun and whatever you do whatever you do don't eat the yellow stay away from that snow the fact that snow looks white right is evidence that it's being illuminated by white light wow that white light is either sunlight or a moonlight that's right which is also reflection of sunlight it's just reflected sunlight there you go this is so disturbing so so so i'm just trying to be honest i'm just trying to put it out there and just and by the way let me take you want to go up a notch are you ready to go up a notch on this i don't know if i'm ready to go up a notch i don't think you're ready okay so um white is the sun i hate where this is going already relative to incandescent bulbs right okay your kids will have no memory of incandescent bulbs but old-timers if you're over 25 you're an old-timer you remember bulbs that would get hot when you put them in it was a bulb with a little piece of wire in it okay i used to light up this sounds like a ken burn special guy on the porch right i remember the days where they had a bulb with a little piece of wire now that wow would light up and get hot now first look like magic [Laughter] okay we gotta put you on the list of the next ken burns special the origin of the light bulbs uh so all right so where it was and i forgot what okay okay you're saying incandescent bulbs okay bulbs incandescent bulbs when you turn them on the temperature of the filament is not as high as the temperature of the surface of the sun and so the higher the temperature the more full that spectrum becomes so if you look at the spectrum of a bulb in your house or an incandescent bulb it's very weak in the blue section there's some blue there which is why blue still looks blue under that light but the blue is very weak under an incandescent light bulb okay so if you bring out film that needs the full complement of blue and you take a picture under incandescent lights everything is going to be red that film if it needed the blue is called daylight film this is why there's a difference again i'm only talking old timers here there was indoor film and tungsten film and outdoor film and the outdoor film was color balanced to get the entire spectrum of the sunlight if you took indoor film and put it outside that indoor film is too sensitive to blue because it's making up for the feeble blue coming out of a bulb and it goes out it's getting all the blue it ever wanted if you have indoor film took a picture outside everything looks blue because it was hypersensitive to blue and the sun has plenty of it okay so to a photographer sunlight is blue it's highly blue and they have to correct for that if they're going from indoors to outdoors they have to redo the color balance on a white sheet of paper to account for the difference between indoor lighting and outdoor lighting now here's where they all got it wrong but they're not going to change it because they're deep into it you ready now we have the blending of science and technology with art you ready here it is if an artist draws an arctic scene what color is prevalent white and what color blue blue right if an artist draws dante's hell what color is prevalent red and orange red and orange okay so emotionally we think of blue as cold and red is hot photographers will tell you we need to reduce the temperature of the light which means make it colder emotionally but the only way to do that is to get more blue in it which means upping the temperature of the tungsten that they have shining on you or to put more blue into it and in the old days that meant a hotter light bulb so they said we need a cooler scene they had to have a hotter bulb we need a warmer scene they had to have a colder bulb to do that wow and that language is still embedded in that entire profession yep that is true the the opposites and they meet in the middle and they deal with it opposites of art and technology and science and and the physics of light all right we got to call it quits there all righty always good to have you chuck always a pleasure this has been the explainer zone i'm sticking with it i like it so keep looking up [Music] you

Channel: StarTalk

Views: 469,549

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Keywords: startalk, star talk, startalk radio, neil degrasse tyson, neil tyson, science, space, astrophysics, astronomy, podcast, space podcast, science podcast, astronomy podcast, niel degrasse tyson, physics, Chuck Nice, Sun, sunlight, white light, blue sky, the sun explained, photography, indoor lighting, outdoor lighting, snow

Id: C9MdbxPCSYw

Length: 14min 26sec (866 seconds)

Published: Tue Jan 19 2021