That is where hydrogen, the nuclear fuel, It takes a photon about 1 millionĬore: The core of the Sun is where the temperature is high enoughįor active nuclear fusion. Interacting with an atom, changing direction, going a short distance, slowlyĭiffusing outward in a random walk. The photons kind of percolate through the layer, going a short distance, From here all the way to the core,Įnergy is not transported by boiling motions, but directly by radiation. Zone: Deeper into the Sun, the plasma suddenly becomes smootherĪnd the turbulence disappears. The convection cells in this layer areįar larger than the surface granulation, and become turbulentĭue to the low viscosity and the rotation of the Sun. Zone: Just beneath the photosphere, and extending inward to aboutĮnergy generated in the core of the Sun moves outward through this layerīy a boiling motion in which hot plasma rises, releases some of its energy,Ĭools, and then sinks again. You look closely at the photosphere away from sunspots, you can see a fine Surfaces about 4000 K or less, and they emit plenty of light. If you could see them in isolation, they would glowīrightly, and would be reddish in color. They only appear dark because they are seen against the brighter, hotter Which inhibit the flow of heat from the hotter surroundings, so they areĬooler (about 4000 K). The sunspots are regions of high magnetic field,

It has a remarkably uniform temperatureĪnd go with time. It is called the photosphereīecause this is the point of the last scattering of photons before theyĮscape directly into space. Out above the limb of the Sun), sunspots (dark spots), and plage (bright Suspended above the surface) and prominences (same as filaments, but sticking Of the solar atmosphere, including filaments (dark clouds of hydrogen gas Strongest spectral lines from the Sun come from the chromosphere, and weĬan take pictures using the light in one of these lines. Hence the name chromosphere, which means color sphere. This is a relatively thin layer that shows as pink during a solar eclipse, Is highly dynamic, and looks different every time you look at it. Light, but also can be seen in visible light during an eclipse (it is too Is very hot (several million K), and so it shines in X-rays and ultraviolet The source of the solar wind is the solar corona, which is the tenuous Wind, which blows past the Earth at speeds from 400-800 km/s (about 1 million Particles and magnetic fields from the Sun make up the solar Wind: Even at the distance of the Earth we can be said to be inside The Structure of the Sun Let's take a lookĪt the structure of the Sun starting from the outside, from Earth, and Meaning that we could power about 14 lightbulbs of 100 W each, for every Power output of the Sun, called the solar luminosity, is constant at 3.8Īmount of power-even at the distance of the Earth we receive 1370 watts/m 2 , The same way, and so all stars have the same basic structure. Larger pieces during the era of bombardment. The end of the formation of the planets, except for the coalescing of the Wind, which swept the solar system clean of gas and dust. Halted the contraction of the Sun, and started a period of strong solar The very inner part became opaque to infrared light and heated up moreĪnd more until the central part reached about 15 million K.Īt this moment that the object became a star.

The object had to cool, which it did by emitting infrared light. Potential energy into kinetic energy, which in turn became heat (remember

Gas, and 1% heavier elements), was very hot, heated by the release of gravitational Same stuff as the rest of the solar nebula (73% hydrogen gas, 26% helium On, the inner part remained in exact gravitational equilibrium, as it does The text calls this gravitationalĮquilibrium-it is when the inner pull of gravity is balancedīy the outward pressure of the hot, dense cloud. Object, where collisions between particles initiated hydrostaticĮquilibrium. Star birth in general, but here are the main events that formed the SunĪ disk from which the planets formed, the central part formed a spherical We will revisit these ideas again when we talk about We glossed over what was happening in the central part that ultimatelyīecame the Sun. The phenomena taking place in the outer reaches of the solar nebula, but Talking about the birth of the solar system from a collapsing cloud, examining Have one star close enough to resolve and study in detail. Since nearly every other star canīe seen only as a mere point of light, we can see how important it is to So what we learn from studying the Sun also applies Our galaxy contains 100 billion suns, and most are ordinary stars very You can see faintly shining in the Milky Way, are suns, similar to ours. Of stars you can see at night with the naked-eye, and all of the millions

Sun corona helium