The Sun Average in size… yes AVERAGE!! Mass is almost 340 000 times that of Earth and a volume that is 1 300 000 times the volume of Earth! Appears to be so much bigger and brighter than other stars because it is so close to Earth

The earth is 150 000 000 (1.5 x 108) km from the sun 1 Astronomical Unit (A.U.) = distance from sun to earth The next nearest star to the Sun is Proxima Centauri at 40 trillion (4.01 x 1013) km from Earth. Most stars are more than 100 trillion (1.0 x 1014) km from Earth.

The Structure of the Sun

The Sun’s Surface Sunspots dark surface spots that are cooler than surrounding area Solar Flares gases and charged particles expelled above the active sunspot Solar Prominences low-energy gas eruptions from the Sun’s surface that extends thousands of kilometres into space

Layers of the Sun’s Atmosphere Above the surface of the sun is its atmosphere, which consists of three parts: Corona 5800 oC gleaming white, halo-like – extends millions of kms into space Chromosphere 65 500 oC Photosphere 5 500 oC The layer just below the Chromosphere where the light we see originates.

The Inside of the Sun Convective zone The outermost ring of the sun, comprising the 30 percent of its radius. Radiative zone The section immediately surrounding the core, comprising 45 percent of its radius. Core hottest part of the Sun - reaching 15 000 000 oC Energy released by nuclear fusion continues to move outward until it reaches the photosphere

process called nuclear fusion occurring in its core Composition 75% hydrogen 25% helium (with small amounts of other gases) Energy Source process called nuclear fusion occurring in its core the temperature and pressure are so high H fuses to become He and releases tremendous amounts of energy Life expectancy 5 billion years old

The Sun’s Effects on Earth The Aurora Borealis (Northern Lights) The Northern Lights are the result of collisions between gaseous particles in the Earth's atmosphere with charged particles released from the sun's atmosphere.

Solar winds travelling toward Earth follow the lines of magnetic force created by Earth’s magnetic field (which is strongest near the NORTH and SOUTH poles). Near the poles, they come in contact with particles in Earth’s atmosphere, producing a display of light in the night sky.

Northern Lights = Aurora Borealis Southern Lights = Aurora Australis

Class/Homework Pg. 312 #1, 2, 6, 8, 9