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

Relative Sizes Characteristics of the SunCharacteristics of the Sun – Teacher’s Domain

Mass  The mass of the Sun is about 2 x 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

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 Inside our Sun a Deeper Look

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 Importance of the Sun Importance of the Sun – 5min The Sun Song The Sun Song - kidsknowit The sun song

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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

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 Light Years Explained

For Example  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 Measuring the UniverseMeasuring the Universe - discovery

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 100,000 Light-Years

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 Light Years Lalande Light Years Sirius A,B 8.6 Light Years

Destination Jet (960 km/h) Rocket (40,000km/h) Sunbeam (300,000 km/sec) Moon16.5 days9.4 hours1.2 seconds Sun17 years, 8 months 4 months8.5 minutes Jupiter74 years, 3 mos1 year, 9 months35 minutes Alpha Centauri (nearest star) 4.8 million years 114,155 years4.2 years Monocerus Nebula years Center of the Milky Way Galaxy ,000 years Andromeda Galaxy million years Hubble Galaxies million years How Fast Can We Get There?

Let’s take a field trip - To build a model to scale the Sun will be a 450 mm balloon the Earth will be a 4 mm lentil and they will be 50 meters apart

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

93,000,000 Miles 1 Astronomical Unit (AU) Sun to Earth Distance

BodyAU Mercury 0.39 Venus 0.72 Earth 1.0 Mars 1.5 Jupiter 5.2 Saturn 9.5 Uranus 19.2 Neptune 30.1 Pluto 39.5