Two positrons are released from this process, as well as two neutrinos which changes two of the protons into neutrons , and energy. The core is the only part of the sun that produces an appreciable amount of heat through fusion. The rest of the sun is heated by the energy that is transferred from the core through the successive layers, eventually reaching the solar photosphere and escaping into space as sunlight or the kinetic energy of particles.
The sun releases energy at a mass—energy conversion rate of 4. To put that in perspective, this is the equivalent of about 9. This is the zone immediately next to the core, which extends out to about 0. There is no thermal convection in this layer, but solar material in this layer is hot and dense enough that thermal radiation is all that is needed to transfer the intense heat generated in the core outward.
Basically, this involves ions of hydrogen and helium emitting photons that travel a short distance before being reabsorbed by other ions. Temperatures drop in this layer, going from approximately 7 million kelvin closer to the core to 2 million at the boundary with the convective zone. Density also drops in this layer a hundredfold from 0.
Here, the temperature is lower than in the radiative zone and heavier atoms are not fully ionized. As a result, radiative heat transport is less effective, and the density of the plasma is low enough to allow convective currents to develop.
Because of this, rising thermal cells carry the majority of the heat outward to the sun's photosphere. Once these cells rise to just below the photospheric surface, their material cools, causing their density increases. This forces them to sink to the base of the convection zone again — where they pick up more heat and the convective cycle continues. At the surface of the sun, the temperature drops to about 5, K.
The turbulent convection of this layer of the sun is also what causes an effect that produces magnetic north and south poles all over the surface of the sun. It is also on this layer that sunspots occur, which appear as dark patches compared to the surrounding region. These spots correspond to concentrations in the magnetic flux field that inhibit convection and cause regions on the surface to drop in temperature to compared to the surrounding material.
Lastly, there is the photosphere, the visible surface of the sun. It is here that the sunlight and heat that are radiated and convected to the surface propagate out into space. Because the upper part of the photosphere is cooler than the lower part, an image of the sun appears brighter in the center than on the edge or limb of the solar disk, in a phenomenon known as limb darkening.
The photosphere is tens to hundreds of kilometers thick, and is also the region of the sun where it becomes opaque to visible light. The reasons for this is because of the decreasing amount of negatively charged Hydrogen ions H— , which absorb visible light easily. Conversely, the visible light we see is produced as electrons react with hydrogen atoms to produce H— ions. The energy emitted from the photosphere then propagates through space and reaches Earth's atmosphere and the other planets of the solar system.
Here on Earth, the upper layer of the atmosphere the ozone layer filters much of the sun's ultra-violet UV radiation, but passes some onto the surface. The energy that received is then absorbed by the Earth's air and crust, heating our planet and providing organisms with a source of energy.
The sun is at the center of biological and chemical processes here on Earth. Without it, the life cycle of plants and animals would end, the circadian rhythms of all terrestrial creatures would be disrupted; and in time, all life on Earth would cease to exist. The sun's importance has been recognized since prehistoric times, with many cultures viewing it as a deity more often than not, as the chief deity in their pantheons. But it is only in the past few centuries that the processes that power the sun have come to be understood.
Thanks to ongoing research by physicists, astronomers and biologists, we are now able to grasp how the sun goes about producing energy, and how it passes that on to our solar system. The study of the known universe, with its diversity of star systems and exoplanets — has also helped us to draw comparisons with other types of stars.
Explore further. More from Astronomy and Astrophysics. Use this form if you have come across a typo, inaccuracy or would like to send an edit request for the content on this page. In the beginning of this century, scientists and engineers began researching ways to use solar energy in earnest.
One important development was a remarkably efficient solar boiler invented by Charles Greeley Abbott, an American astrophysicist, in The solar water heater gained popularity at this time in Florida, California, and the Southwest.
The industry started in the early s and was in full swing just before World War This growth lasted until the mid- s when low-cost natural gas became the primary fuel for heating American homes. The public and world governments remained largely indifferent to the possibilities of solar energy until the oil shortages of the s.
Today people use solar energy to heat buildings and water and to generate electricity. Solar Collectors and Solar Space Heating.
Heating with solar energy is not as easy as you might think. Capturing sunlight and putting it to work is difficult because the solar energy that reaches the earth is spread out over a large area. The sun does not deliver that much energy to any one place at any one time. How much solar energy a place receives depends on several conditions. These include the time of day, the season of the year, the latitude of the area, and the clearness or cloudiness of the sky.
A solar collector is one way to collect heat from the sun. A closed car on a sunny day is like a solar collector. As sunlight passes through the car's glass windows, it is absorbed by the seat covers, walls, and floor of the car. The light that is absorbed changes into heat. The car's glass windows let light in, but don't let all the heat out.
This is also why greenhouses work so well and stay warm year-round. Space heating means heating the space inside a building. Today many homes use solar energy for space heating. There are two general types of solar space heating systems: passive and active. A "hybrid" system is a mixture of the passive and active systems. In a passive solar home, the whole house operates as a solar collector. A passive house does not use any special mechanical equipment such as pipes, ducts, fans, or pumps to transfer the heat that the house collects on sunny days.
Instead, a passive solar home relies on properly oriented windows. Since the sun shines from the south in North America, passive solar homes are built so that most of the windows face south. They have very few or no windows on the north side. A passive solar home converts solar energy into heat just as a closed car does.
Sunlight passes through a home's windows and is absorbed in the walls and floors. To control the amount of heat in a passive solar house, the doors and windows are closed or opened to keep heated air in or to let it out. At night, special heavy curtains or shades are pulled over the windows to keep the daytime beat inside the house.
In the summer, awnings or roof overhangs help to cool the house by shading the windows from the high summer sun. Heating a house by warming the walls or floors is more comfortable than heating the air inside a house.
It is not so drafty. And passive buildings are quiet, peaceful places to live. A passive solar home can get 50 to 80 percent of the heat it needs from the sun. Many homeowners install equipment such as fans to help circulate air to get more out of their passive solar homes.
When special equipment is added to a passive solar home, the result is called a hybrid system. Unlike a passive solar home, an active solar home uses mechanical equipment, such as pumps and blowers, and an outside source of energy to help heat the house when solar energy is not enough. Active systems use special solar collectors that look like boxes covered with glass.
Dark-colored metal plates inside the boxes absorb the sunlight and change it into heat. Black absorbs sunlight more than any other color. Air or a liquid flows through the collectors and is warmed by this heat. The warmed air or liquid is then distributed to the rest of the house just as it would be with an ordinary furnace system. Solar collectors are usually placed high on roofs where they can collect the most sunlight.
They are also put on the south side of the roof where no tall trees or tall buildings will shade them. The simple answer is that the Sun, like all stars, is able to create energy because it is essentially a massive fusion reaction.
Scientists believe that this began when a huge cloud of gas and particles i. This not only created the big ball of light at the center of our Solar System, it also triggered a process whereby hydrogen, collected in the center, began fusing to create solar energy.
Technically known as nuclear fusion, this process releases an incredible amount of energy in the form of light and heat. But getting that energy from the center of our Sun all the way out to planet Earth and beyond involves a couple of crucial steps.
It is here, in the core, where energy is produced by hydrogen atoms H being converted into molecules of helium He. This is possible thanks to the extreme pressure and temperature that exists within the core, which are estimated to be the equivalent of 2 50 billion atmospheres The net result is the fusion of four protons hydrogen molecules into one alpha particle — two protons and two neutrons bound together into a particle that is identical to a helium nucleus.
Two positrons are released from this process, as well as two neutrinos which changes two of the protons into neutrons , and energy. The core is the only part of the Sun that produces an appreciable amount of heat through fusion. The rest of the Sun is heated by the energy that is transferred from the core through the successive layers, eventually reaching the solar photosphere and escaping into space as sunlight or the kinetic energy of particles.
The Sun releases energy at a mass—energy conversion rate of 4. To put that in perspective, this is the equivalent of about 9. Radiative Zone: This is the zone immediately next to the core, which extends out to about 0. There is no thermal convection in this layer, but solar material in this layer is hot and dense enough that thermal radiation is all that is needed to transfer the intense heat generated in the core outward.
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