Why Is The Sky Blue And The Sunset Red?

Why Is The Sky Blue And  The Sunset Red?

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Exploring the Science Behind  Blue Skies and Red Sunsets Why is the Sky Blue and the Sunset Red? Every kid has asked us a question that usually  sounds like the following: “Why is the water   in the sea blue, but as soon as I touch it, it  becomes transparent?” And our answer would be:   “Because the sea is only reflecting  the color of the sky, which is blue.   But water doesn’t have a color”. And if we  are unlucky, the kid then asks, “Okay then,   why is the sky blue?”. And somehow, it seems  like a hard question to answer. But don’t worry,   you’ve come to the right place to be able  to understand why in fact the sky appears   to blue and why it changes color depending  on where the Sun is located in the sky. Through this video, you will explore the  scientific answers to these questions and   find out why our sky and sunsets appear with such  vibrant colors. Dive into the world of light,  

matter and atmosphere and learn the reason  behind the mesmerizing blues and reds of the sky. Keep watching to never hesitate ever  again when a child asks you this   question. ---- The sky is one of the most mysterious and  captivating things in our environment;   it's constantly changing and  always fascinating to look at.

First of all, it is important to understand that  the sky is not blue because of a pigment. The   universe and the night sky are essentially black  due to the absence of light. Where there are no   stars to emit light, there is no visible light and  therefore it is black. The air is not blue either:   air and gaseous oxygen are both transparent,  allowing visible light to pass through. Therefore, the origin of the blue sky  color is not pigmentary, but structural:   the process that creates it is purely  physical. It is an action of matter on light,   and this is what allows to act on specific  colors even without pigments being involved.

In the case of the sky, the colors making up  white light are refracted. It is also said to   be diffused. This phenomenon is called something  known as the Rayleigh Scattering, which is when   molecules and particles in the atmosphere break  up visible light into its component colors. First, it's important to understand the basics  of light and what happens when light passes   through the atmosphere. White light consists of  all the colors of the visible spectrum - red,  

orange, yellow, green, blue, and purple. But  when light passes through our atmosphere,   the molecules and particles in the  air break it up into different colors. When the sun is high in the sky, most of the blue  light gets scattered throughout the atmosphere.   The Rayleigh scattering causes  blue light to be scattered much   more than other colors. So this  is why the midday sky looks blue.

But then why does the sky  appear blue and not violet?   Wouldn’t it make more sense, knowing  that the Rayleigh scattering disperses   more the shorter wavelengths are,  that the sky appears to be violet? Well, in fact, violet is scattered even more  than blue. The trick here is that, although   violet is indeed part of the solar spectrum,  our star emits much less violet than blue. These very short wavelengths are  not very present in sunlight.   In fact, the peak in the spectrum, that is, the  most emitted wavelength in the solar spectrum,   is green. So, there is more green than blue,  than violet, and even red or orange. We  

don’t see it though, as the mix we perceive is  mostly white, or yellow, at the ground level. If the sun was much hotter to the point  of emitting more violet than blue,   the sky would appear to be  something like a bluish purple.   Moreover, ultraviolet, whose wavelength is  even shorter, is so much dispersed that UV   cameras images are naturally blurred because  of it, even for a landscape not too far away. Does that explain why we see the Sun as  yellow when in fact it emits white light? Yes, it’s explained by the fact that the Sun  is very, very far away from us. It is like a  

big glowing ball of light in the sky. When we look  up at it from the ground, it looks yellow. That is   because of the air in the sky. It filters out some  of the colors, so we only see yellow. It’s like   a little fun coloring game: We have White minus  Blue which gives us Red plus Yellow plus Green. And I presume you all know your additive  colors: Red and Green make yellow. Overall,  

we obtain the color yellow, seen  from the ground. But if you look at   pictures taken from space, you can  see that the Sun is really white. The Sun is actually referred to as a "yellow  dwarf star," which is a term used to describe   its size. However, even though it is  classified as a yellow dwarf star,   it is not because of its color. The  term "yellow dwarf" simply indicates   that the sun is of a certain size which is  typical for stars in this classification. The lower the sun is in the sky, the more  atmosphere its light has to travel through   before reaching our eyes. This means that  more of the blue light will be scattered away,  

leaving primarily the reddish component of  white sunlight to travel directly to our eyes.   As a result, the setting sun will look red.  This is because the shorter wavelength blue   light interacts more with the small molecules,  causing it to be bounced away from the original   sunlight path. Thus, less blue light reaches our  eyes, resulting in the red hue of the sunset. This phenomenon is naturally more noticeable  in places with less air pollution and in areas   that are farther away from cities, as large  amounts of airborne dust and particulates   can block the red light from reaching our  eyes. Additionally, dust and debris in the   atmosphere can cause the sun to look orange  or even purple when it is low in the sky.   This occurs because dust and particulates  scatter different intensities of light at   different angles, causing some regions of  the sun to appear brighter than others.

As the sun sets, the sky turns darker and  darker until it eventually becomes black. The setting of the sun marks the end of the day  and the beginning of the night. As the sun slowly   sets, the sky gradually turns from a deep blue to  a dark, star-studded black. Watching the sun set   is a beautiful and calming experience, one that  can make anyone feel at peace with the world. To add to this, what's really fascinating  is that the same effect that causes the sky   to appear blue and sunsets to be red can  also be seen in other parts of the world.   For example, if you look at the sky in Antarctica  in the middle of summer, the sky appears a   brilliant green color due to the increased  number of ozone particles in the atmosphere.  

This is because when the sun is lower  in the sky in the polar regions,   the light is reflecting off the particles in the  atmosphere in a way that makes the sky look green. There’s also another reason for a green  sky to appear, taking for example what’s   been happening in South Dakota. I’m  sure you’ve seen it on social media. Residents of Sioux Falls, South Dakota,  witnessed an unusual phenomenon on Tuesday   night as a derecho storm brought  powerful winds and a green sky.   The green hue was caused by severe thunderstorms  with a lot of water content that scattered blue   light combined with red and yellow light  from a sunset. Social media users posted   images of the strange sky and the Department of  Transportation traffic cameras also captured it.   Meteorologists explained that the green  sky can be indicative of large hail. If  

you haven’t seen all the cool pictures capturing  the green sky, don’t hesitate to take a look. What would the sky look like in different  worlds? With different atmospheres? Let’s take a look at the Moon, our favorite  neighbor. The Moon does not have an atmosphere,   no light from the Sun is being scattered  by the molecules making up the atmosphere,   therefore there is no specific  color for a sunset on the Moon.   The Sun will look white all throughout  its trajectory in the sky of the Moon. An interesting comparison would be considering the  Martian sky. The sky on Mars looks very strange   compared to the sky we see here on Earth. The  sky near the Sun looks blue and the sky far away  

from the Sun looks red. That’s because there is a  lot of special dust in the air on Mars. This dust   scatters the sunlight, so it looks blue near the  Sun and red far away. When the Sun sets on Mars,   it looks extra blue and beautiful because of the  dust! But even more interesting is the night sky   on Mars. We can often see celestial objects  that are too dim to be seen on Earth without  

a telescope. Mars has no bright moon like Earth,  so the stars shine very brightly in the night sky.   When you look up on a Martian night you can see  constellations of stars, galaxies and even distant   planets! It’s a view that is truly breathtaking  and awe-inspiring! But that’s for another video!   This universe is a fascinating one,  you start with one simple question   like why the sky is blue on Earth and find  yourself diverging talking about the night   sky on Mars. ---- That concludes our video on why the sky is blue  and why sunsets are red. We hope you enjoyed the  

journey and learned something new along the way.  Don't forget to explore and observe the night sky,   because there are countless amazing and  awe-inspiring things out there that we   can learn from. Until next time, stay  insanely curious and keep exploring! Why is it so difficult to return to  the moon if we have done it before? The last time a human was on the Moon was in 1972.  Since then, technology has taken giant steps, and  

more and more countries have developed their space  program, but despite this, human beings have not   returned to visit the Moon. What are the reasons? Let's find out!  The main motivation To find the reasons that led to the trip   to the Moon, we have to go back to the end of the  decade of, the 60s. After World War II, during the   Cold War, the United States and the Soviet Union  engaged in the Space Race, a stubborn struggle   between the two powers whose ultimate goal was  to place a citizen of the nation on the surface   of the Moon. From this struggle, in which both  nations intended to demonstrate their military   and technological superiority over the adversary,  the United States would emerge as the winner.  The trip to the Moon, more than an end in itself,  was a way to show the world who would set the pace   of the international political agenda for the  remainder of the century. Reaching the Moon had  

more of a political purpose than a scientific one. In a different historical context, out of simple   scientific concern, would we have reached  the Moon in '69? Everything seems to indicate   that it does not. As we have said, the  motivation for the Americans to send a   human-crewed mission to our satellite was the  tension generated by the political situation.   Without this rivalry with the USSR, it would have  been hard to imagine that the American government   would mobilize the nearly 400,000 people who  participated in the Apollo program and dedicated   to it during the 14 years that it lasted, the  equivalent today of about 120,000 million dollars.  Today it is unimaginable that the U.S.  government would again fund a trip of  

this nature at such high costs to the nation. The high cost of stepping on the moon again  Reaching the moon was not an easy feat  to achieve because, in addition to the   technological challenges we will discuss later,  there were also many economic challenges.  A law signed in March 2017 by President  Donald Trump gives NASA an annual budget   of around $19.5 billion and stands at nearly $20  billion today. But although this sounds like an   astronomical figure, in reality, it is not if you  consider that the total is divided between all the   divisions of the agency and all the ambitious  projects like the James Webb Space Telescope,   the giant rocket project called the Space Launch  System and remote missions to the Sun, Jupiter,   Mars, the asteroid belt, the Kuiper  belt and the edge of the solar system.  In addition, NASA's budget is  somewhat small relative to its past.   Since 1960 the economic allocation dedicated  to the American space program skyrocketed,   reaching the record figure of 5.3% of the national  budget in 1965. But five years later, in the early  

70s and resolved the Space Race in favor of  the Americans, NASA suffered a significant   budget cut for various reasons, including  the loss of political interest in the Moon   and the accident the Apollo 13 mission suffered. These events would lead to the cancellation of the   Apollo 18, 19, and 20 missions, making Apollo  17 the last human-crewed mission to the Moon.   As a result, for the last 40 years,  NASA's budget has remained below 1%,   and for the last 15 years, it has been  heading toward 0.4% of the federal budget. 

In other words, if today we have not  returned to the moon, it is, on the one hand,   a lack of interest on the part of governments  and, secondly, a lack of economic resources.  What happened to technology? Today NASA has the new rocket SLS ("Space   Launch System"), which will be the successor  of the Atlas V that was responsible for taking   astronauts to the Moon; this rocket made its  debut with the launch of the Artemis 1 Mission,   which was a success, managing to take the  Orion capsule to the orbit of the Moon,   which will be the new spacecraft that will  transport humans to the lunar surface.  Something that caught the attention of many is  that before the launch of the Artemis1 mission,   it was canceled two times due to failures  in the rocket's fuel chambers of the rocket,   and therefore it was necessary to perform  more tests before the ship could be launched. 

But why was it so difficult to launch the SLS?   Isn't NASA supposed to have  years of experience already?  The reality is that the launches of the  Apollo missions were not easy either;   as you will remember, the mission that managed to  land successfully was the 11th; that is to say,   before the 11, ten missions did  not get it for various reasons,   most of them had several cancellations either  due to weather problems or technical problems.  Some Apollo missions didn't even get off  the ground, but it's hardly talked about.   It is also worth remembering that during the  space shuttles, NASA had many problems getting   make them taken off even though they already  had the experience of the Apollo spacecraft.  The most common problems during shuttle  launches were almost always in fueling   systems since this was not the same as that  of Saturn V rockets and Apollo spacecraft. 

The shuttles were extremely complex craft  that mixed a rocket's power with an airplane's   aerodynamics and had engines that used solid  and liquid fuel. This complexity was what caused   technical failures in all launch attempts. In fact, according to the registry of launch   cancellations, shuttle launches are the  ones that suffered the most cancellations;   some were canceled up to 5 times  before taking off successfully.  The problem of fuel supply Before successfully taking off,   the Artemis 1 mission was canceled two times  due to technical failures in the fuel system;   these failures are the same ones that caused  the cancellation of the Apollo missions and   the same ones suffered by the shuttles. Fuel leaks are the most common failure   in rockets and one of the main reasons for  takeoff cancellation for more than 50 years,   but why does this problem still exist today? The fault lies with the fuel used by the rockets,   HYDROGEN. This is the simplest and  lightest element of all; on earth,   it exists in abundance, but it  is mixed with other elements,   and molecular separation processes such as  electrolysis must be used to obtain pure hydrogen. 

Hydrogen is a highly light element, so much so  that putting together a single gram of material   requires billions of hydrogen atoms. Hydrogen is  so light that it can sneak through any opening,   however tiny it may be; in a typical  environment and average temperatures,   this is not usually a problem, but leaks are  much easier to occur in a cold environment   and high pressures. It is precisely these  environments in which space rockets operate.  For a rocket's fuel tanks to remain full of  fuel, they must be permanently connected to   terrestrial cooling systems by cables  and hoses until the moment of launch.  At the time of takeoff, some connections  separate from the bridge; it is right here   where leaks usually occur since these  connections cannot be screwed tightly,   and it is tough to avoid leaks when they are  at high pressures and shallow temperatures.  In short, it's hard for rockets to take  off because hydrogen is used as fuel.  But... if this is the problem,  why not use another fuel? 

Reusing rockets The reason why NASA continues to use hydrogen fuel   is its high efficiency since it is the element  that provides greater thrust and less weight.   Still, another important reason  is the law; we are not talking   about physical laws but political ones. In 2010 the U.S. Congress ordered that   NASA would have to continue using the rockets  that were used in the shuttles as part of the   SLS rocket program; in fact, you may not know  it, but the SLS engines are the same as those   used by the space shuttles at the time. As the budget was cut, Congress suggested   that to optimize resources, NASA would have  to use the contracts, investments, budget,   workforce, industrial base, and existing  infrastructure in the U.S. that were used   for the space shuttle in the new SLS program. Likewise, would also be reused the Orion 1,   and the existing propulsion systems, such as the  liquid fuel engines that cause so many leaks,   the external storage tank, and the solid  fuel engines, would also be reused. 

All this was reused and conditioned to  the new Artemis 1 project. In other words,   the Artemis project, which seeks to take new  astronauts to the Moon, uses the same technology,   rockets, engines, and launch base that  space shuttles used more than a decade ago.  That's why getting back to the Moon  is so tricky; beyond touch screens,   the technology of the Artemis 1 program is not  so different from what we had 50 years ago.  Moreover, perhaps the most potent reason we  haven't returned to the Moon is the simplest   of all: there hasn't been a need to go back. The  missions of the Apollo program were so prolific   that apart from the countless experiments  carried out on the Moon, so many samples of   lunar material were collected that even today,  many of them remain unstudied by scientists.  To all this, we must add that in the coming  years, NASA's interests will focus on objectives   such as Skylab, the laboratory in Earth orbit,  or sending probes and satellites to many other   corners of the solar system. And perhaps  the question is: Why should we return to  

the Moon when there is so much still to  be explored on the rest of the planets?  In light of recent scientific advances, there  is nothing to criticize NASA for. Today we   explore Mars with robots, discover new solar  systems almost daily, and detect phenomena such   as gravitational waves that until very  recently were only part of the theory.  As we have seen, there are several reasons  why we have not been to the Moon since 1972,   and yet none has to do, for example, with the  strange conspiracy theories circulating for   several years on social networks. Just because  we haven't come back doesn't mean we won't.  The horizon of the next human-crewed mission to  our satellite will be marked by NASA's Artemis   project that aims to put a man back on the Moon.  And it may also be that on this occasion imitating  

Neil Armstrong in 1969, is a woman who takes a  new step on the surface of our natural satellite.

2023-02-28 04:49

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