The Sun *Our closest star *Accounts for 99.8% of the solar system’s total mass *because of this, it exerts powerful gravitational force throughout the solar system *this force decreases with distance but is strong enough to hold all planets in orbit

Sun’s Interior Ball of glowing gas, (not a solid surface like Earth) ¾ Hydrogen ¼ Helium Small amounts of other elements Has an interior Has an atmosphere

Sun’s Interior Has 3 Zones: Core Radiation zone Convection zone This Photo by Unknown Author is licensed under CC BY-SA

Core Central region of sun Energy comes from nuclear fusion Hydrogen atoms join together to form helium in this process Occurs under conditions of high temperature and pressure (about 15 million degrees Celsius Energy slowly moves out from the core, eventually escaping into space

Radiation Zone Middle layer of sun’s interior Tightly packed gas Energy is transferred in form of electromagnetic radiation Very dense *because of its density, it takes 100,000 years for energy to move through it

Convection Zone Outermost layer of sun’s interior Hot gases rise from bottom of this zone Gases cool as they get to the top of this zone Loops of gas form and move toward the sun’s surface

Sun’s Atmosphere Photosphere Chromosphere Corona

Photosphere Inner layer of atmosphere Seen when you look at an image of the sun Considered to be sun’s surface layer Moon blocks the light of photosphere during solar eclipse

Chromosphere Means “color sphere” This Photo by Unknown Author is licensed under CC BY-SA Chromosphere Means “color sphere” Reddish glow that appears during a solar eclipse is cause by this layer

Corona “white halo” during a solar eclipse Means “crown” in Latin This Photo by Unknown Author is licensed under CC BY-SA-NC “white halo” during a solar eclipse Means “crown” in Latin Corona extends into space for millions of kilometers Thins into streams of electrically charged particles called solar wind

Layers of the Sun This Photo by Unknown Author is licensed under CC BY-SA-NC

Sun’s Features Sunspots Prominences Solar flares

Sunspots Dark spots on sun’s surface Sunspots are larger than Earth (but appear small) Cooler than the gases around them, so it is darker and doesn’t give off as much light Appears to move across sun’s surface Proves sun rotates on its axis just like Earth does This Photo by Unknown Author is licensed under CC BY-SA

Huge, reddish loops of gas Prominences Huge, reddish loops of gas Loops can be seen extending over the edge of the sun This Photo by Unknown Author is licensed under CC BY-SA-NC

Solar Flares Magnetic energy Gas eruptions into space This Photo by Unknown Author is licensed under CC BY-NC-ND