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The Sun The sun is a medium size star It appears larger than the other stars because of its relative nearness to the earth It consists of about 70% Hydrogen, 28% Helium and 2% of metals such as iron Size The sun is 1,390,000 km in diameter You could fit 1 million earths inside the sun The planet Venus just passing in front of the Sun Our Sun is so large …. it would take 108 Earths laid side-by-side to go across the Sun’s diameter Characteristics of the Sun – Relative Sizes Mass The mass of the Sun is about 2 x 1030 kilograms It is one of the larger stars in our Milky Way galaxy The mass of the Sun is over 300,000 times greater than that of the Earth Distance The Sun is 149,600,000 km (92 million miles) from the Earth Since the speed of light is 303,000 km/sec (186,000 miles/second), it takes the light slightly over 8 minutes to get from the Sun to the Earth Inside our Sun a Deeper Look Temperature Its temperature is extremely hot, with the surface being about 5000° C and the center core at 15,600,000° C The high temperature in the core, along with extreme pressure from the Sun's mass, result in nuclear fusion reactions Nuclear fusion converts hydrogen to helium producing energy Importance of the Sun Without the Sun, the Earth would not be able to support life It is the main source of energy for earth It provides light and heat It’s necessary for plants to carry out photosynthesis The Sun Song - kidsknowit The sun song Importance of the Sun – 5min Powers of Ten The Milky Way The Milky Way is a cluster of stars, called a galaxy It contains hundreds of billions of stars If you traveled at the speed of light for about 2 million years, you would reach the next galaxy – the Andromeda Galaxy There are billions of galaxies in the universe Light Years Explained Distance to Stars Astronomers use light-years and astronomical units to measure distance A light-year is the distance that light travels in one year In space, light travels at a speed of 300,000 km per second A light year is about 9.5 million million km (9,460,730,472,580.8) About 6 trillion miles For Example Measuring the Universe - discove If you ride your bike at 10 kilometers per hour, it would take you 1 hour to go to a mall 10km away You could say that the mall is 1 bike-hour away Actual Distance from the Sun to the Earth How long does it take light to get from the Sun to the Earth? 8 minutes It takes 16 minutes to go there and back Stars Betelgeuse: 427 light years Rigel: 773 light years Orion Nebula: 1600 light years Key Idea The light-year is a unit of distance, not time! The Milky Way Galaxy is about 100,000 light years across Powersof10.com Nearby Stars: Name Distance from Earth Sun 93 million miles (8 light min) Proxima Centauri 4.22 Light Years Alpha Centuri A,B 4.39 Light Years Barnards Star 5.94 Light Years Wolf 359 7.8 Light Years Lalande 21185 8.3 Light Years Sirius A,B 8.6 Light Years How Fast Can We Get There? Destination Jet (960 km/h) Rocket (40,000km/h) Sunbeam (300,000 km/sec) Moon 16.5 days 9.4 hours 1.2 seconds Sun 17 years, 8 months 4 months 8.5 minutes Jupiter 74 years, 3 mos 1 year, 9 months 35 minutes Alpha Centauri (nearest star) 4.8 million years 114,155 years 4.2 years ------------------- ------------------- 109 years Center of the ------------------Milky Way Galaxy ------------------- 38,000 years Andromeda Galaxy ------------------- ------------------- 2.2 million years Hubble Galaxies ------------------- ------------------- 400 million years Monocerus Nebula Astronomical Unit The distance of the Sun to the Earth is called an Astronomical Unit (AU) and is sometimes used to denote large distances that are less than a light year A light year is about 63,241.1 astronomical units Sun to Earth Distance 1 Astronomical Unit (AU) 93,000,000 Miles Body Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto AU 0.39 0.72 1.0 1.5 5.2 9.5 19.2 30.1 39.5