1. Full name Period II. Chapter 14, section 2: The Sun A. The Sun: is our local star. 1. Spectral Class: G2. 2. Distance to Earth:149,600,000 km *At the speed of Light: 8 min. 19s 3. Volume: 1.41 x 10 km 18 3 *~1,300,000 of Earth’s volume 4. Surface gravity: 29.94 g * 1g = Earth’s gravity 5. Luminosity (brightness): 3.846 x 10 W (watts) 26 6. Element composition a. Hydrogen (H) 73.46% (its present energy source) b. Helium (He) 24.85% c. Oxygen (O) 0.77% d. All other elements < 1%

2. c. Oxygen (O) 0.77% d. All other elements < 1% B. The Sun’s layers from the outside – in. (Theoretical) 2. Corona (crown) is the outer most layer that surrounds the sun. a. Can only be seen during a total solar eclipse. b. Extends for millions of kilometers, becoming the solar wind 1. Solar wind is made of electrically charged particles; given off by the sun. a. Extending beyond the distances of the planets b. Can be damaging

3. Full name 3. Chromosphere: is a red glowing layer of the sun. a. 2000 km in depth b. Can shed parts of itself into space (Sun Flares). 4. Photosphere: is the bright layer of the sun. a. Has the density of gas b. Temperature between 4,230 and 5,730 °C

4. 5. Convection zone: has gases circulate b. Cooled gases drop to lower layer below. 6. Radiation zone. a. A very dense region a. Hot gases rise to the photosphere and release their energy. b. Takes energy over 100,000 to 1 million years to go through this zone. 7. The core. a. is the region where the sun’s energy is generated. b. Nuclear fusion: 4 hydrogen atoms = 1 helium atom & LOTS of energy!!! c. 30 time the size of the Earth.

5. Period II. Chapter 14, section 2: The Sun (continued) B. The Sun Energy. 1. Nuclear Fusion: is the process of taking the nuclei of atoms and combining them together. 2. Star nuclear fusion (during its main sequence) a. 4 hydrogen atoms = 1 helium atom & LOTS of energy!!! b.