1. The Sun Unit 5 PESS 2

2. Energy from the Sun Electromagnetic energy is a type of energy that can travel through space an example is visible light Light travels in wavelengths Light travels in wavelengths –There are many things that travel in wavelengths (radio waves, microwaves, ultraviolet rays, x-rays) The electromagnetic spectrum breaks visible light down into the colors that make it up –When you shine light through a prism you can see the different colors of visible light

3. Electromagnetic Radiation Visible light is composed of red, orange, yellow, green, blue and violet – like a rainbow Visible light is composed of red, orange, yellow, green, blue and violet – like a rainbow

4. Energy from the Sun In a process called nuclear fusion the sun gives off electromagnetic energy Nuclear fusion can only occur at extremely high temperatures (~15 million °C) Nuclear fusion can only occur at extremely high temperatures (~15 million °C) –Helium and hydrogen atoms fuse together giving off an enormous amount of energy (enough to supply the solar system for billions of years!) There is enough helium and hydrogen in the sun to last about 10 billion years – the sun is only about 5 billion years old There is enough helium and hydrogen in the sun to last about 10 billion years – the sun is only about 5 billion years old

5. Measuring our Solar System Since the solar system is so large scientists developed the unit called an Since the solar system is so large scientists developed the unit called an astronomical unit or au The distance between the sun and Earth is 1au

6. The Sun’s Interior Consists of: Core, Radiation zone, Convection zone Core –Where nuclear fusion occurs –About 400,000km Radiation zone Radiation zone –Region of highly compressed gases –Takes energy “light” about 10,000 years to pass through Convection zone Convection zone –Convection currents move the energy to the atmosphere

7. The Sun’s Atmosphere There are 3 layers – the photosphere, the chromosphere and the corona The Photosphere –The inner layer –Technically, the “surface” –About 5800K and 500km thick The Chromosphere –The middle layer –Gives off a reddish glow –About 10,000K –Visible during a total solar eclipse

8. The Sun’s Atmosphere The Corona –The white halo around the sun –Visible on Earth only during eclipses or by special telescopes –Sends out a stream of electrically charged particles called solar wind –The Earth’s atmosphere normally blocks out solar wind, but near the north and south poles some particles enter creating auroras –About 1 million K

9. Features of the Sun The sun rotates on its axis, just like all the other planets in the solar system The sun rotates on its axis, just like all the other planets in the solar system Sunspots Sunspots –Small, dark spots on the sun (small for the sun because they are about the size of Earth) –Sunspots are areas of gas that are cooler than the gases around it – since they are cooler they do no give off as much light and appear dark

10. Features of the Sun Scientists believe that the number of sunspots change over 10 years or so – meaning that the amount of energy produced by the sun also changes Scientists believe that the number of sunspots change over 10 years or so – meaning that the amount of energy produced by the sun also changes Prominences Prominences –A group of sunspots that link together and create reddish loops –If a prominence is near the edge of the sun scientists can actually see them stick out from the sun’s surface

11. Features of the Sun Solar flares –When sunspots suddenly connect and release a large amount of energy into space –The gases contract an heat to even greater temperatures causing hydrogen gas to explode into space –Solar flares can cause magnetic storms in the upper atmosphere of Earth disrupting radios, telephones, television, and causing electrical problems