2. The Sun By: JGilliam

3. The Sun’s CompositionIdentifying Stars Composition ▪ Hydrogen and Helium together make up 99% of the sun’s mass. ▪ 75% of the sun’s mass is Hydrogen. ▪ Mainly ionized gasses ▪ Scientist break up the star’s light into spectra by using a device called a Spectrograph. ▪ Using these Spectra, scientist can identify the certain elements that are present in a star’s atmosphere. ▪ Scientist can also deduce the temperature, density, and pressure of the gas. ▪ Because each element produces unique patterns of spectral lines, scientist can match the spectral lines of starlight to those of Earth’s elements, and identify the elements in the star’s atmosphere. Spectral Lines Spectrograph

4. Nuclear Fusion in the Sun ▪ Nuclear Fusion: The process by which nuclei of small atoms combine to form a new, more massive nucleus; the process releases energy. This occurs inside the sun. ▪ Fusion releases huge amounts of energy. ▪ Hydrogen atoms are the primary fuel for the sun’s fusion. ▪ Hydrogen atoms commonly consist of only one proton and one electron. However, electrons are stripped from the protons by the Sun’s intense heat. ▪ During fusion a subatomic particle, called a neutrino, is given off. Neutrinos escape the sun and reach Earth in about eight minutes. Studies of these particles indicate that the sun is fueled by fusion.

5. Nuclear Fusion Steps Nuclear Fusion consist of three steps  In the first step, two hydrogen nuclei, or protons, collide and fuse. The positive charge of one of the protons is neutralized as that proton emits a particle called a positron. As a result the proton become a neutron and changes the original two protons into a proton-neutron pair.  In the second step, another proton combines with the proton-neutron pair to produce a nucleus made up of two protons and one neutron.  In the third step, two nuclei made up of two protons and one neutron collide and fuse. As this fusion happens, two protons are released. The remaining two protons and one neutron fuse together and form a helium nucleus.  Final Product- One of the final products of the fusion of hydrogen in the sun is always a helium nucleus. The helium nucleus has about 0.7% less mass than the hydrogen nuclei that combined to form it. The lost mass is converted into energy during the series of fusion reactions that forms helium. Because all nuclear fusion releases energy, the three steps of nuclear fusion cause the sun to shine and gives the sun it’s high temperatures. Key: Protons – positive Electrons – negative Neutrons - neutral

6. The Sun’s Interior

7. The Core ▪ Makes up 25% of the sun’s total diameter. ▪ The Core’s temperature is about 15,000,000˚c. No solids or liquids can exist at such a high temperature ▪ Like the rest of the Sun the core is made up entirely of ionized gasses ▪ Because of the sun’s large mass, the pressure from the Sun’s material is so great that the core is more than ten times as dense as iron. ▪ The enormous pressure and high temperature of the Sun’s core strip away electrons from the atomic nuclei. Also, the conditions force positive nuclei to fuse.

8. The Radiative Zone  Radiative zone: The zone of the Sun’s interior that is between the core and the convective zone and in which energy moves by radiation.  The temperature ranges from about 2,000,000˚c to 7,000,000˚c  Energy moves outward in the form of electromagnetic waves or radiation.

9. The Convective Zone ▪ Convective zone: The region of the Sun’s interior that is between the radiative zone and the photosphere and in which energy is carried upward by convection. ▪ The temperature is about 2,000,000˚c. ▪ Energy moves through this zone by convection.

10. The Sun’s Atmosphere

11. The Photosphere “ Sphere of Light” ▪ Photosphere: The visible surface of the sun. ▪ Made up of the gasses that have risen from the Convective zone. ▪ The temperature is about 6,000˚c ▪ Referred to as the Sun’s surface because this layer is the visible surface of the Sun.

12. The Chromosphere “Color Sphere” ▪ Chromosphere: The thin layer of the sun that is just above the photosphere and that glows a reddish color during eclipses. ▪ A thin layer of gasses that glows with reddish light that is typical of the color given off by Hydrogen ▪ The temperature ranges from 4,000˚c to 50,000˚c ▪ The gasses of the Chromosphere move away from the photosphere ▪ In upward motion, gas regularly forms narrow jets of hot gas that shoot outward to form the Chromosphere and then fade away within a few minutes. Some of these jets can reach heights of 16,000km

13. The Corona “Crown” ▪ Corona: The outermost layer of the sun’s atmosphere. ▪ A huge region of gas that has a temperature above 1,000,000˚c ▪ It is not very dense, but it’s magnetic field can stop most subatomic particles from escaping into space ▪ Ions do escape as the Corona expands. These particles make up the solar wind which flows outward from the sun to the rest of the solar system. The Transition Region ▪ Just above the Chromosphere is a thin zone called the transition region where the temperature rises dramatically.

14. The Sun Size: Diameter of 1,390,000km; 218.4x Earth’s Color: Generally a orange/yellow color Features: Sunspots Rotation: Equator – 25.3 days Poles – 33 days Density: 1.409 g/cm³: 0.256 that of Earth’s Gravity: 274.0 m/s²; 27.96x Earth’s Atmosphere: Mostly gasses that have risen off the Convective Zone Surface: Energy moves through the Convective Zone and outward; made up of ionized gasses Interior: No liquids or solids can exist in the interior. Made up of ionized gasses Magnetic field: Unidentified Moons: None Unique: 4.6 billion years old

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