Moving outward, next comes the radiative or radiation zone. Its name is derived from the way energy is carried outward through this layer, carried by photons as thermal radiation. The third and final region of the solar interior is named the convective or convection zone. It is also named after the dominant mode of energy flow in this layer; heat moves upward via roiling convection, much like the bubbling motion in a pot of boiling oatmeal.
The boundary between the Sun's interior and the solar atmosphere is called the photosphere. It is what we see as the visible "surface" of the Sun. This structure of the photosphere is called granulation see Figure 5 Granules, which are typically to kilometers in diameter about the width of Texas , appear as bright areas surrounded by narrow, darker cooler regions.
The lifetime of an individual granule is only 5 to 10 minutes. Even larger are supergranules, which are about 35, kilometers across about the size of two Earths and last about 24 hours. The motions of the granules can be studied by examining the Doppler shifts in the spectra of gases just above them see The Doppler Effect.
The bright granules are columns of hotter gases rising at speeds of 2 to 3 kilometers per second from below the photosphere. As this rising gas reaches the photosphere, it spreads out, cools, and sinks down again into the darker regions between the granules.
Measurements show that the centers of the granules are hotter than the intergranular regions by 50 to K. Figure 6. Because they are transparent to most visible radiation and emit only a small amount of light, these outer layers are difficult to observe.
Until this century, the chromosphere was visible only when the photosphere was concealed by the Moon during a total solar eclipse see the chapter on Earth, Moon, and Sky. Observations made during eclipses show that the chromosphere is about to kilometers thick, and its spectrum consists of bright emission lines, indicating that this layer is composed of hot gases emitting light at discrete wavelengths.
The reddish color of the chromosphere arises from one of the strongest emission lines in the visible part of its spectrum—the bright red line caused by hydrogen, the element that, as we have already seen, dominates the composition of the Sun.
In , observations of the chromospheric spectrum revealed a yellow emission line that did not correspond to any previously known element on Earth. It took until for helium to be discovered on our planet. Today, students are probably most familiar with it as the light gas used to inflate balloons, although it turns out to be the second-most abundant element in the universe.
The temperature of the chromosphere is about 10, K. This means that the chromosphere is hotter than the photosphere, which should seem surprising. In all the situations we are familiar with, temperatures fall as one moves away from the source of heat, and the chromosphere is farther from the center of the Sun than the photosphere is.
Figure 7. Temperatures in the Solar Atmosphere: On this graph, temperature is shown increasing upward, and height above the photosphere is shown increasing to the right.
Note the very rapid increase in temperature over a very short distance in the transition region between the chromosphere and the corona. The increase in temperature does not stop with the chromosphere. Above it is a region in the solar atmosphere where the temperature changes from 10, K typical of the chromosphere to nearly a million degrees.
The hottest part of the solar atmosphere, which has a temperature of a million degrees or more, is called the corona. Appropriately, the part of the Sun where the rapid temperature rise occurs is called the transition region. It is probably only a few tens of kilometers thick. Figure 7 summarizes how the temperature of the solar atmosphere changes from the photosphere outward.
IRIS is the first space mission that is able to obtain high spatial resolution images of the different features produced over this wide temperature range and to see how they change with time and location Figure 8. Figure 3 and the red graph in Figure 7 make the Sun seem rather like an onion, with smooth spherical shells, each one with a different temperature.
For a long time, astronomers did indeed think of the Sun this way. For example, clouds of carbon monoxide gas with temperatures colder than K have now been found at the same height above the photosphere as the much hotter gas of the chromosphere.
Figure 8. An image of a portion of the transition region of the corona, showing a filament, or ribbon-like structure made up of many individual threads. Like the chromosphere, the corona was first observed during total eclipses Figure 9.
Unlike the chromosphere, the corona has been known for many centuries: it was referred to by the Roman historian Plutarch and was discussed in some detail by Kepler. Answer from: weeblordd. Explanation: Sun's core: The Sun's core is the central region. Answer from: 21hendlill. I hope this helps.
Sorry if I made any mistakes. Answer from: isaiyt. Photosphere,chromosphere and the corona Hope it helps!!! Answer from: earcake The solar atmosphere includes the chromosphere and corona. Another question on Geography. Acounterculture is composed of a group of people who the dominant culture. Which is a possible result of higher air temperatures caused by global warming?
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Instead, the sun is composed of layers made up almost entirely of hydrogen and helium. The sun is permeated and somewhat controlled by a magnetic field. Magnetic field lines that flow through the poles extend much farther, thousands of kilometers, before returning to the opposite pole. The sun rotates around its own axis, just like Earth. The sun rotates counterclockwise, and takes between 25 and 35 days to complete a single rotation.
The sun orbits clockwise around the center of the Milky Way. Its orbit is between 24, and 26, light-years away from the galactic center. The sun takes about million to million years to orbit one time around the galactic center.
The electromagnetic spectrum exists as waves of different frequencies and wavelengths. The frequency of a wave represents how many times the wave repeats itself in a certain unit of time. Waves with very short wavelengths repeat themselves several times in a given unit of time, so they are high-frequency. In contrast, low-frequency waves have much longer wavelengths.
The vast majority of electromagnetic waves that come from the sun are invisible to us. The most high-frequency waves emitted by the sun are gamma rays, X-rays, and ultraviolet radiation UV rays. Less potent UV rays travel through the atmosphere, and can cause sunburn. The sun also emits infrared radiation —whose waves are a much lower-frequency. Most heat from the sun arrives as infrared energy.
Sandwiched between infrared and UV is the visible spectrum, which contains all the colors we, as humans, can see. The color red has the longest wavelengths closest to infrared , and violet closest to UV the shortest. The sun itself is white, which means it contains all the colors in the visible spectrum. The sun appears orangish-yellow because the blue light it emits has a shorter wavelength , and is scattered in the atmosphere—the same process that makes the sky appear blue.
Evolution of the Sun The sun, although it has sustained all life on our planet, will not shine forever. The sun has already existed for about 4. Through nuclear fusion, the sun is constantly using up the hydrogen in its core :Every second, the sun fuses around million metric tons of hydrogen into helium. Over the next five billion years, the sun will burn through most of its hydrogen, and helium will become its major source of fuel.
The outer layers of the sun will expand from this extra energy. The sun will expand to about times its current radius, swallowing Mercury and Venus.
As the sun expands, it will spread its energy over a larger surface area, which has an overall cooling effect on the star. When it reaches this temperature, helium will begin fusing to create carbon, a much heavier element. This will cause intense solar wind and other solar activity, which will eventually throw off the entire outer layers of the sun. The red giant phase will be over. Temperatures in the core exceed The core is the only place where nuclear fusion reactions can happen.
Protons of hydrogen atoms violently collide and fuse, or join together, to create a helium atom. This process, known as a PP proton-proton chain reaction, emits an enormous amount of energy. The energy released during one second of solar fusion is far greater than that released in the explosion of hundreds of thousands of hydrogen bombs.
During nuclear fusion in the core, two types of energy are released: photons and neutrinos. These particles carry and emit the light, heat, and energy of the sun. Photons are the smallest particle of light and other forms of electromagnetic radiation. The sun emits both photons and neutrinos in all directions, all the time. Radiative Zone The radiative zone of the sun starts at about 25 percent of the radius, and extends to about 70 percent of the radius. In this broad zone, heat from the core cools dramatically, from between seven million K to two million K.
In the radiative zone, energy is transferred by a process called thermal radiation. During this process, photons that were released in the core travel a short distance, are absorbed by a nearby ion, released by that ion, and absorbed again by another.
One photon can continue this process for almost , years! Transition Zone : Tachocline Between the radiative zone and the next layer, the convective zone, there is a transition zone called the tachocline.
Differential rotation happens when different parts of an object rotate at different velocities. The sun is made up of gases undergoing different processes at different layers and different latitudes.
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