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. For general inquiries, please use our contact form.
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By using our site, you acknowledge that you have read and understand our Privacy Policy and Terms of Use. The interior structure of the Sun. On the interactive, you will need to click the forward and back arrows to move through the five steps in this simplified pathway. To play the interactive a second time, click the "start over" button at the end of the slides. Note: the representations of the processes are not drawn to scale. Next, in order to gain a deeper understanding of Earth's radiation balance, use the following interactive to step through how the energy is moving from the sun to Earth and back out to space.
Read the text and study the graphics in this interactive. On the interactive, you will need to click on the text in the images to gather the details needed to answer the questions about the Global Energy Balance. To access the interactive, you can click the link or the image, left, to view the interactive.
Use your Back button to return to this page when you are done viewing the interactive. After studying the interactive, answer the Checking In questions listed below about the Global Energy Balance. Now that you have worked through the Global Energy Balance interactive, review the annual Earth's Energy Balance diagram pictured below. In order to simplify your accounting, you will break the process of energy flow into three parts. Use the diagrams and text below to guide your steps.
While the process is continuous, and not step-by-step, this activity will help you to separate out the details and create an energy "account. You will also need 3 colored pencils: red, blue, and orange. Once you have gathered your materials, you will read a section of the printed instructions and then move pennies representing the energy from one location to the next.
Overview of Energy Pathways Begin this activity by gaining an overview of the energy pathways. Using the graphic shown above, identify the incoming solar radiation.
On your printed version of the graphic, color the incoming radiation blue. Next, color the arrows representing outgoing radiation red, and the latent and sensible heat arrows orange.
You have now separated the incoming and outgoing radiation. Part 1. Incoming Solar Radiation. Solar energy, in the form of radiation, is constantly moving through space; bathing our planet and its atmosphere. The radiation that arrives at the top of the atmosphere is either reflected or absorbed.
In Part 1, you saw that about 30 percent of incoming sunlight is reflected back to space by particles in the atmosphere or bright ground surfaces, which leaves about 70 percent to be absorbed by the atmosphere 23 percent and Earth's surface 47 percent including the ocean.
For the energy budget at Earth's surface to balance, processes on the surface must transfer and transform the 47 percent of incoming solar energy that the ocean and land surfaces absorbed back into the atmosphere and eventually space. What is latent heat and how is it important in the atmosphere? What is conduction? What is insolation? How much incoming solar radiation is initially transmitted by the atmosphere? How much incoming solar radiation is initially reflected off earth's surface?
The Sun The heat that eventually causes the earth to warm actually comes from the sun. What Are the Elements of Uranus?
What Type of Star Is the Sun? Why Is the Sun So Bright? Parts of a Star. Unique Facts About the Sun.
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