Scale of the Universe By the end of this lesson you will: Have an understanding about the scale of the Solar System and the Universe Know what a light year is used to measure

Scale of the Solar System How far away are the different planets in our Solar System?

Distances in our Solar System Name of Planet Distance from Sun (in kilometres) Scale Distance (in metres) Mercury 57,910,000 Venus 108,200,000 Earth 149,600,000 Mars 227,900,000 Jupiter 778,500,000 Saturn 1,433,000,000 Uranus 2,877,000,000 Neptune 4,503,000,000

Distances in our Solar System Using a scale of 10,000,000 km = 1 metre Name of Planet Distance from Sun (in kilometres) Scale Distance (in metres) Mercury 57,910,000 Venus 108,200,000 Earth 149,600,000 Mars 227,900,000 Jupiter 778,500,000 Saturn 1,433,000,000 Uranus 2,877,000,000 Neptune 4,503,000,000

Distances in our Solar System Using a scale of 10,000,000 km = 1 metre Name of Planet Distance from Sun (in kilometres) Scale Distance (in metres) Mercury 57,910,000 5.79 Venus 108,200,000 10.82 Earth 149,600,000 14.96 Mars 227,900,000 22.79 Jupiter 778,500,000 77.85 Saturn 1,433,000,000 143.30 Uranus 2,877,000,000 187.70 Neptune 4,503,000,000 450.03

Distances in our Solar System Using a scale of 100,000,000 km = 1 metre Name of Planet Distance from Sun (in kilometres) Scale Distance (in metres) Mercury 57,910,000 0.58 Venus 108,200,000 1.08 Earth 149,600,000 1.50 Mars 227,900,000 2.28 Jupiter 778,500,000 7.79 Saturn 1,433,000,000 14.33 Uranus 2,877,000,000 28.77 Neptune 4,503,000,000 45.03

Distances to Stars Distances are so vast in space that an alternative unit to metres is necessary...

…Light Years (Not Buzzes) A light year is the distance travelled by light in one year. A Light-Year is a measure of distance (NOT TIME)!

Distance = speed x time = 300,000,000 x 31,536,000 = 9.46x1015 meters To calculate this we use the speed-distance-time equation: Speed = the speed of light = 300,000,000 meters per second Time = 1 year = (365 x 24 x 60 x 60) = 31536000 seconds Distance = speed x time = 300,000,000 x 31,536,000 = 9.46x1015 meters = 9,460,000,000,000,000 m (nine quadrillion, four hundred and sixty trillion metres!!!!!)

Scale of the Universe Summary Do you now have an understanding about the scale of the solar system and the Universe? Do you now know what a light year is used to measure?