Like all other star, it is composed of burning gases such as hydrogen and helium. Our Sun is a 4.5 billion-year-old star a hot glowing ball of hydrogen and helium at the center of our solar system. Meanwhile, elements heavier than helium form in the Sun's core. School:Johnson City Primary School, Johnson City Central School District. copyright 2003-2023 Study.com. Heres how it works. He points to a 2015 study in Nature indicating that metals might increase opacity even more than previously thought in the high-pressure conditions of the suns core. Sun. They're areas where the magnetic field of the Sun is unusually strong. At a conference last month in Heidelberg, Germany, the Borexino experiment based at Italys Gran Sasso National Laboratory reported detections of solar neutrinos that marginally favor the higher, 1.8 percent estimate of the suns metallicity. (along with the hydrogen, helium, etc), What is thE sun made of like how was it built or something. WebThe Sun is a huge, glowing sphere of hot gas. Carbon, nitrogen and oxygen make up 1.5% and the other 0.5% is made up of small amounts of many other elements such as What is the Sun Made Of? The sun as it appeared in October 2017, imaged by NASAs Solar Dynamics Observatory. Temperatures in this region are cool enough that the atoms have enough energy to hold their electrons. But its the suns tiny concentration of heavier elements, which astronomers call metals, that controls its fate. The radius of the Sun, R, is 109 times that of Earth, but its distance from Earth is 215 R, so it subtends an angle of only 1/2 in the sky, roughly the same as that of the Moon. Web1. About 67 chemical elements have been detected in the sun. Most of the gas around 92% is hydrogen, according to NASA. The Sun is a star. This is because some of the light that left the sun was absorbed by atoms (like H and He) in the suns atmosphere. The middle (equator) of the Sun rotates faster than the poles. Video: Join David Kaplan on a virtual-reality tour showing how the sun, the Earth and the other planets came to be. Milky way a spiral galaxy with a disk about 100,000 light-years in diameter and containing between 100 billion and 1 trillion stars solar system the Sun and all the objects that orbit it. The Sun is a very stable source of energy; its radiative output, called the solar constant, is 1.366 kilowatts per square metre at Earth and varies by no more than 0.1 percent. Have you ever wondered what about the other elements in the Sun? I think it should be rewritten. In the coming years, the Borexino team expects to detect rare solar neutrinos produced in the CNO cycle, a fusion reaction in the sun in which carbon, nitrogen and oxygen atoms serve as catalysts for fusing hydrogen into helium. Our Sun is surrounded by a jacket of gases called an atmosphere. The Sun is not, as is often said, a small star. While Earth is only the fifth largest planet in the solar system, it is the only world in our solar system with liquid water on the surface. [21] The Sun is a G-type main-sequence star (G2V), informally called a yellow dwarf, though its light is actually white. Global temperatures were the hottest on record for 3 days in a row in July, Hubble telescope captures the making of a 'cosmic monster' (photo), By Elizabeth Howell, Daisy DobrijevicJuly 13, 2023. Like all other star, it is composed of burning gases such as hydrogen and helium. But the Sun doesn't really have a specific surface. She discovered that H and He accounted for most of the atoms of our sun and other stars, contrary to what had been thought. Jupiter shines near the moon with the Seven Sisters of the Pleiades on July 14. Light below the photosphere can't make it out of the Sun without first being absorbed, so the photosphere is an opaque layer. The material that makes up the Sun just gets less and less dense gradually until all you have is empty space. Most of this gas is hydrogen (about 70%) and helium (about 28%). Carbon, nitrogen and oxygen make up 1.5% and the other 0.5% is made up of small amounts of many other elements such as neon, iron, silicon, magnesium and sulfur. What Is the Sun Made Of? So what is the sun made of? The Sun's surface is made up of a very hot, ionized gas called plasma. The temperature of the Suns surface is so high that no solid or liquid can exist there; the constituent materials are predominantly gaseous atoms, with a very small number of molecules. Under the force of gravity, the great mass of the Sun presses inward, and to keep the star from collapsing, the central pressure outward must be great enough to support its weight. After years of talking about what might be going wrong including speculations about dark matter in the sun the debate has reached a bit of a stalemate, said Sarbani Basu, a solar astrophysicist at Yale University. Surprisingly, no one knows the stars exact chemical composition: how many carbon, nitrogen and oxygen atoms they have relative to hydrogen, the most common element. Most of the gas around 92% is hydrogen, according to NASA. WebStudents know the Sun, an average star, is the ventral and largest body in the solar system and is composed primarily of hydrogen and helium. The sun is chemically composed of hydrogen and helium. I would definitely recommend Study.com to my colleagues. Just slightly larger than nearby Venus, Earth is the biggest of the four planets closest to the Sun, all of which are made of rock and metal. The exact composition of the Sun is yet to be determined, as is an understanding of how that chemical makeup resulted in the diverse collection of planets and other bodies in the solar system. Sunspots are most common during intense solar activity, and that activity can affect the Earth: It can disrupt electronic equipment, and may even affect the climate. What's the Difference Between a Solstice and an Equinox? They also have a stronger magnetic field, but that field is more focused into a small area than with sunspots. Gravity then pulls together the burning gases of the Sun and stars. The CNO neutrinos are greatly affected by metallicity, so measuring these neutrinos could be definitive, said Andrea Pocar, a physicist at the University of Massachusetts Amherst and a member of the Borexino collaboration. The corona is the outermost part of the Sun's atmosphere. [21] The Sun is a G-type main-sequence star (G2V), informally called a yellow dwarf, though its light is actually white. If you've ever seen a blacksmith create a sword or other metal item, you know that it takes a lot of heat to shape metal. galaxy collection of a few hundred million to a trillion or more stars, bound together by gravity. galaxy collection of a few hundred million to a trillion or more stars, bound together by gravity. The equator of the Sun actually rotates faster than the polar regions. Get highlights of the most important news delivered to your email inbox. They're the top of convection cells, or areas of the Sun where the plasma underneath is rising together. This gravitational pull is 28 times the gravitational pull on the surface of the Earth. The photosphere is 100 kilometers thick, and has a temperature of 6000 kelvin. The two elements came from the Big Bang process and account for 98% of the celestial object's mass. galaxy collection of a few hundred million to a trillion or more stars, bound together by gravity. This snapshot from NASA's Solar Dynamics Observatory shows a stunning prominence associated with a Sept. 8, 2010 solar flare. The sun is made of about three-quarters hydrogen, one-quarter helium, and some other heavier elements like carbon, oxygen and iron, in very small quantities. But, the density of the gas in the sun changes quite a lot, depending on its location in the sun. But if astronomers theory of the sun, called the standard solar model, is correct, spectroscopy and helioseismology should agree. Granules are the grainy pattern we see on the photosphere that are the tops of convection cells bubbling up to the surface. That makes it difficult While Earth is only the fifth largest planet in the solar system, it is the only world in our solar system with liquid water on the surface. The Sun is a 4.5 billion-year-old yellow dwarf star a hot glowing ball of hydrogen and helium at the center of our solar system. I feel like its a lifeline. There are only trace amounts of other elements, including oxygen, carbon, nitrogen, silicon, magnesium, neon, iron, and sulfur. About 67 chemical elements have been detected in the sun. The Sun is a huge, glowing sphere of hot gas. However, we do have a name for the bright light that appears to be a surface: we call it the photosphere. The two elements came from the Big Bang process and account for 98% of the celestial object's mass. The star at the center of the solar system. WebWhat is the Sun made of? But have you ever wondered what it would be like to stand on the surface of the Sun? Cool Cosmos is an IPAC website. If we change the solar yardstick, automatically it means that our understanding of the cosmos has to change, said Martin Asplund, an astrophysicist at Australian National University. The surface is so hot that anyone who was actually there would be vaporized instantly. SpaceKids on SPACE.com provides simple, straightforward answers to really big cosmic questions. What is the Sun made of that releases heat to keep us going? The Sun is so far from Earth that this slightly fuzzy surface cannot be resolved, and so the limb (the visible edge) appears sharp. The middle rotates once every 28 days or so. By mass the composition of the sun is 92.1% hydrogen and 7.9% helium. Moderators are staffed during regular business hours (New York time) and can only accept comments written in English. The star at the center of the solar system. These values are estimates based on the relative intensity of spectral lines. The Sun is a 4.5 billion-year-old yellow dwarf star a hot glowing ball of hydrogen and helium at the center of our solar system. That makes it difficult The Sun is a huge, glowing sphere of hot gas. The Latest New NASA Map Details 2023 and 2024 Solar Eclipses in the US The Sun is classified as a G2 V star, with G2 standing for the second hottest stars of the yellow G classof surface temperature about 5,800 kelvins (K)and the V representing a main sequence, or dwarf, star, the typical star for this temperature class. Meaghann has a bachelor's degree in physics and astronomy from Alfred University and a master's degree in astrophysics from the Rochester Institute of Technology. We call this the photosphere. Have you ever wondered what about the other elements in the Sun? When you look at the Sun, you're not just seeing the outer layer glowing, you're actually seeing light from many layers underneath as well. Beyond a distance of 5R from the Sun, the corona flows outward at a speed (near Earth) of 400 kilometres per second (km/s); this flow of charged particles is called the solar wind. If you took the gas from the core of the sun, the balloon would weigh about 2,500 pounds. Since the Sun isn't solid, that means you can see through layer after layer of plasma. The photosphere has many different markings and features that astronomers can study to better understand how the Sun works. Hydrogen makes up 72% of the mass of the sun, helium another 26%, and the remaining 2% is made up of oxygen, neon, nitrogen, carbon, magnesium, silicon, and iron. This process releases huge amounts of energy in the form of heat and light. Fusion. WebWhat is the Sun made of? What Is the Sun Made Of and When Will It Die? The corona is the outermost part of the Sun's atmosphere. The Sun is the closest star to Earth and the center of our solar system. Turns out, the sun is made up of several gasses. The sun is a big ball of gas and plasma, but what is the sun made of exactly? Nuclear reactions at the core of the Sun change hydrogen into helium and then generate massive heat. https://www.thoughtco.com/element-composition-of-sun-607581 (accessed July 17, 2023). Does the heat generate all the way to the core. The sun consists mostly of hydrogen and helium. The energy-producing reaction that occurs inside stars. Sun. To unlock this lesson you must be a Study.com Member. The sun is mostly composed of the elements hydrogen (H) and helium (He). You may know the Sun consists mainly of hydrogen and helium. The Sun is the source of an enormous amount of energy, a portion of which provides Earth with the light and heat necessary to support life. The next most abundant element is helium, which accounts for almost just under 9% of the atoms and about 27% of the mass. Most of the gas around 92% is hydrogen, according to NASA. Turns out, the sun is made up of several gasses. Create your account. Without the Suns energy, life as we know it could not exist on our home planet. And this is basically the same reason that the Sun glows so bright and appears to have a surface. the sun seems to be so hot but we are so far away from it. Inland Sea photosphere of the Sun The radius of the Sun, R, is 109 times that of Earth, but its distance from Earth is 215 R, so it subtends an angle of only 1/2 in the sky, roughly the same as that of the Moon. Carbon, nitrogen and oxygen make up 1.5% and the other 0.5% is made up of small amounts of many other elements such as Based on Government Sponsored Research NAS7-03001 and NNN12AA01C. Ever wonder how long will the Sun release those vast amounts heat and light energy? The Sun rotates, just like the Earth and other planets do. Suns Structure The sun is made up of six layers: core, radiative zone, convective zone, photosphere, chromosphere, and corona. Just slightly larger than nearby Venus, Earth is the biggest of the four planets closest to the Sun, all of which are made of rock and metal. Most of this gas is hydrogen (about 70%) and helium (about 28%). The Sun's surface is made up of a very hot, ionized gas called plasma. We can't visit the Sun to sample it directly, and even if we could, scientists would still need to estimate the concentration of elements in other portions of the star. When you magnify the surface, you see that it isn't continuous but is made up of these tiny granules. To unlock this lesson you must be a Study.com Member. The entire Sun glows and appears to have an outer surface, just like the hot metal does as it glows red and orange when it is heated. This makes the convection zone darker or more opaque, trapping heat and causing the plasma appear to boil from convection. Unfortunately for the sun itself (and future life on Earth), low-metallicity stars burn fuel faster than high-metallicity stars, so our sun would die about a billion years sooner than we thought. Although it falls midway between the biggest and smallest stars of its type, there are so many dwarf stars that the Sun falls in the top 5 percent of stars in the neighbourhood that immediately surrounds it. WebThe Sun is a star. universe There's no official point where the Sun starts. The more metallic a star, the more opaque it is (since metals absorb radiation), and how opaque it is in turn relates to its size, temperature, brightness, life span and other key properties. WebWhat is the Sun mainly made of? By comparison, Proxima Centauri, the next closest star to Earth, is 250,000 times farther away, and its relative apparent brightness is reduced by the square of that ratio, or 62 billion times. Most of this gas is hydrogen (about 70%) and helium (about 28%). These trace elements make up less than 0.1 percent of the mass of the Sun. Recently, a weak hint about the solar metallicity has come from fleeting particles emanating from the sun called solar neutrinos. How can the gases of the sun burn when there is no oxygen in space? Even gases and plasmas will glow when heated enough. By comparison, the core is 15 million kelvin. Space is part of Future US Inc, an international media group and leading digital publisher. On top of it, you can see features like sunspots, faculae and granules. Because it is made of gas, the Sun does not have a solid surface. This energy is released in outer space as heat and light which provide the living things and the whole solar system the heat it needed. WebThe Sun is a huge, glowing sphere of hot gas. Our Sun is a 4.5 billion-year-old star a hot glowing ball of hydrogen and helium at the center of our solar system. Web1. The Sun's surface is made up of a very hot, ionized gas called plasma. The Elemental Composition of the Human Body, Journey Through the Solar System: Our Sun, Stellar Nucleosynthesis: How Stars Make All of the Elements, 7 Extinction Level Events That Could End Life as We Know It, What the Numbers on the Periodic Table Mean, Journey Through the Solar System: Planet Uranus, Ph.D., Biomedical Sciences, University of Tennessee at Knoxville, B.A., Physics and Mathematics, Hastings College. ThoughtCo. The corona is usually hidden by the bright light of the Sun's surface. As a result, there is no fixed surface. The Sun's photosphere and atmosphere are very dynamic and change frequently. It is the largest and most massive object in the solar system therefore all planets, comets, and asteroids orbit around it. This plasma is mostly comprised of hydrogen and some helium in the Sun's core. Scientists researched the capabilities of the Sun and have found out that it would still be able to produce energy for 10 more billion years! Here's how to see it. Let us know if you have suggestions to improve this article (requires login). Why are sunspots darker than the rest of the Sun? The sun is made of about three-quarters hydrogen, one-quarter helium, and some other heavier elements like carbon, oxygen and iron, in very small quantities. Similar to a blacksmith heating a sword, the Sun glows because it is hot just like a metal sword does when it is being forged. The exact composition of the Sun is yet to be determined, as is an understanding of how that chemical makeup resulted in the diverse collection of planets and other bodies in the solar system. Carbon, nitrogen and oxygen make up 1.5% and the other 0.5% is made up of small amounts of many other elements such as neon, iron, silicon, magnesium and sulfur. WebRoughly three-quarters of the Sun's mass consists of hydrogen (~73%); the rest is mostly helium (~25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron. A star has a very different composition when compared to the Earth. Most of this gas is hydrogen (about 70%) and helium (about 28%). If you consult other sources, you'll see the percentage values vary by up to 2% for hydrogen and helium. David has taught Honors Physics, AP Physics, IB Physics and general science courses. universe Perhaps the most obvious problem with a trip to the Sun is the sheer heat it produces. The pattern of light absorbed by each atom also depends on its temperature. | 21 Ask a Scientist runs on Sundays. universe Its like a teacher waved a magic wand and did the work for me. However, throughout the 2000s, increasingly precise spectroscopic measurements of sunlight a direct probe of the suns composition, since each element creates telltale absorption lines in the spectrum indicated a far lower metallicity of just 1.3 percent. This sequence of calculations should predict the same value for the metallicity as spectroscopers measure directly from sunlight. Core The suns core , more than a thousand times the size of Earth and more than 10 It keeps the family together, so to speak, through its gravitational pull. NY 10036. Without the Suns energy, life as we know it could not exist on our home planet. this is so strange for us to comprehend. Energy in the photosphere is released as light, which travels through the solar atmosphere (the chromosphere and corona) and passes into space. New York, Astronomers inability to solve the mystery known variously as the solar metallicity, solar abundance, solar composition or solar modeling problem suggests there could be something fundamentally wrong with their understanding of the sun, and therefore of all stars, said Vagnozzi. The photosphere rotates, but because it isn't solid, not all of it rotates at the same rate. Inland Sea photosphere of the Sun The radius of the Sun, R, is 109 times that of Earth, but its distance from Earth is 215 R, so it subtends an angle of only 1/2 in the sky, roughly the same as that of the Moon. Table of Element Composition. All rights reserved. Our Sun is surrounded by a jacket of gases called an atmosphere. For more about nuclear fusion and how the Sun shines, see Spitzer's IRrelevant Astronomy video Fission vs. Fusion. [21] The Sun is a G-type main-sequence star (G2V), informally called a yellow dwarf, though its light is actually white. WebWhile the Sun is mostly made up of hydrogen and helium, there are small amounts of all other elements as well. They have lower temperatures and usually last for a few days. The Sun is about 93 million miles (150 million kilometers) from Earth, and without its energy, life as we know it could not exist here on our home planet. Source:NASA - Goddard Space Flight Center. Breaking space news, the latest updates on rocket launches, skywatching events and more! Dont worry. Astronomers continue to observe the Sun and its many features daily to better understand our closest star. WebWhile the Sun is mostly made up of hydrogen and helium, there are small amounts of all other elements as well. The sun is chemically composed of hydrogen and helium. Learn about the surface of the sun, what it looks like, does the sun have a solid surface, and the name of the surface of the sun. When looking at light from the sun, this trick gets a little more complicated because of the suns high temperature. While every effort has been made to follow citation style rules, there may be some discrepancies. The mass of the Sun, M, is 743 times the total mass of all the planets in the solar system and 330,000 times that of Earth. So having an accurate knowledge of the solar chemical composition is extremely important., Yet, ever more precise measurements of the suns metallicity have raised more questions than theyve answered. The Sun also rotates, similar to how Earth rotates. The photosphere is made out of a very, very hot gas called plasma that mostly consists of hydrogen and a small amount of helium in the Sun's core. WebStudents know the Sun, an average star, is the ventral and largest body in the solar system and is composed primarily of hydrogen and helium. Star. The nuclei of atoms are completely stripped of their electrons, and at this high temperature they collide to produce the nuclear reactions that are responsible for generating the energy vital to life on Earth. If it turns out that the sun is, in fact, only 1.3 percent metal, this would mean the standard solar model really does have opacity wrong. Have you ever wondered what about the other elements in the Sun? 2023 www.pressconnects.com. Like any star in its prime, the sun consists mainly of hydrogen atoms fusing two by two into helium, unleashing immense energy in the process. The Sun's heat passes through its surface, and in turn heats the surface of the Earth. You may know the Sun consists mainly of hydrogen and helium. Please agree and read more about our. What is the Sun Made Of? Like any star in its prime, the sun consists mainly of hydrogen atoms fusing two by two into helium, unleashing immense energy in the process. Turns out, the sun is made up of several gasses. It is the dominant body of the system, constituting more than 99 percent of its entire mass. The photosphere is about 100 kilometers thick and about 10,000 degrees F. There are many features that can be observed on the Sun's photosphere including sunspots, faculae, and granules. Is the sun made of just gases or dust too? The photosphere is yellow, with darker sunspots, brighter faculae, and details called granules on the top of it. The solar system is named after the Sun- solar means the Sun. Without it, we could never survive. The two elements came from the Big Bang process and account for 98% of the celestial object's mass. This is the layer of the Sun we cannot see through and therefore appears as the familiar yellow disk that we see on a clear day. Because the photosphere is very hot gas, the Sun does not really have a solid surface. Helmenstine, Anne Marie, Ph.D. "What Is the Sun Made Of? It still has about 5 billion years before the hydrogen runs out. The Sun is so large that about one million planet Earths could fit inside the Sun if it were hollow. The sun is a big ball of gas and plasma, but what is the sun made of exactly? Surprisingly, no one knows the stars exact chemical composition: how many carbon, nitrogen and oxygen atoms they have relative to hydrogen, the most common element. The layer of the Sun we see as the surface is called the photosphere. Direct and indirect ways of inferring its metallicity both gauged the sun as approximately 1.8 percent metal a happy convergence that led them to believe they understood not only the length of their solar yardstick but also how the sun works. Plasma is found both on the Sun's surface and the Sun's interior layers. A huge ball of very hot gases in space. What is it that makes the Sun the powerhouse of our solar system and the source of almost all of the Earths various forms of energy? Underneath the photosphere, the Sun boils in violent convection cells of rising and sinking plasma. All the interesting planetary and interplanetary gravitational phenomena are negligible effects in comparison to the force exerted by the Sun. Plasma is found both on the Sun's surface and the Sun's interior layers. Large amounts of energy are produced by the Sun and the stars mainly due A huge ball of very hot gases in space. The Sun's photosphere is the layer of the Sun that becomes opaque, meaning we can no longer see through it. Sun, star around which Earth and the other components of the solar system revolve. The Sun's rays give plants and animals the warmth and energy we need to survive on Earth. Suns Structure The sun is made up of six layers: core, radiative zone, convective zone, photosphere, chromosphere, and corona. Updates? The Sun is a huge, glowing sphere of hot gas. But its the suns tiny concentration of heavier elements, which astronomers call metals, that controls its fate. Create your account. It is part of the"observable universe,"the region ofspacethat humans can actually or theoretically observe with the aid of technology. Although the spectrum we can analyze comes from the solar photosphere and chromosphere, scientists believe it is representative of the whole Sun, except for the solar core. It cannot burn because there is no oxygen on the sun. Hydrogen and Helium - Major Components of the Sun. Different nuclear fusion reactions produce solar neutrinos of different energies, and so the particles carry information about the suns composition. Author of. This article wasreprinted onTheAtlantic.com and in Spanish atInvestigacionyciencia.es. The sun is made of about three-quarters hydrogen, one-quarter helium, and some other heavier elements like carbon, oxygen and iron, in very small quantities. They write new content and verify and edit content received from contributors. North Korea launches ICBM on record-breaking 74-minute flight, Space Force wants 'Foo Fighter' satellites to track hypersonic missiles, India's moon-landing mission is 'go' for Friday morning launch (photos), Still live after Amazon Prime Day: Canon EOS R6 is $500 off, How China will land astronauts on the moon by 2030, ULA delays Vulcan rocket's debut to late 2023 after fireball during test, 'Star Wars' TV shows snag 22 Emmy nominations, 'Star Trek: Strange New Worlds' costume designer dishes on her dazzling outfits (exclusive), Jam packed issues filled with the latest cutting-edge research, technology and theories delivered in an entertaining and visually stunning way, aiming to educate and inspire readers of all ages, Engaging articles, breathtaking images and expert knowledge. The Sun is a 4.5 billion-year-old yellow dwarf star a hot glowing ball of hydrogen and helium at the center of our solar system. It does not. Sunspots are dark areas on the surface. flashcard sets. Our Sun is a 4.5 billion-year-old star a hot glowing ball of hydrogen and helium at the center of our solar system. Sun. For more information, visit binghamton.edu/mpr/ask-a-scientist/. And the Sun produces a huge amount of heat through a process called nuclear fusion. It keeps the planet warm enough that we don't freeze to death. Hydrogen and Helium - Major Components of the Sun. Get a Britannica Premium subscription and gain access to exclusive content. The sun is a big ball of gas and plasma, but what is the sun made of exactly? No, the sun is not burning, as stated in this article. The sun is mostly composed of the elements hydrogen (H) and helium (He). WebWhat is the Sun mainly made of? What is the sun made of? 30 chapters | Gravity then pulls together the burning gases of the Sun and stars. She has over 5 years of experience teaching physics and astronomy in both formal and informal settings. You may know the Sun consists mainly of hydrogen and helium. And this depth relates, according to the equations, to the suns opacity, and therefore to its metallicity. Each color is light of a different energy, with blue light having about one-third more energy than red light. Omissions? Milky way a spiral galaxy with a disk about 100,000 light-years in diameter and containing between 100 billion and 1 trillion stars solar system the Sun and all the objects that orbit it. Various metals make up less than 0.1% of the mass of the sun. The corona is usually hidden by the bright light of the Sun's surface. You may know the Sun consists mainly of hydrogen and helium. Light above the photosphere is completely free to exit the Sun without being absorbed first.
Cornshucker Silver Slugger Nit,
Church Street Apartments Burlington, Vt,
Wild Boar Hunting Ohio Public Land,
Iowa City Cedar Rapids Corridor,
Articles W