What is a Light Year? http://janus.astro.umd.edu/astro/distance/
If you could travel to the closest star from the sun in a car traveling 60 mph, how long would it take you to get there? http://janus.astro.umd.edu/astro/distance/
48 million years
If you could travel to the closest star from the Earth in a space shuttle at 18,000 mph, how long would it take you to get there?
160,000 years
If you ride on a beam of light, how long would it take you to get there? It travels 300,000,000 m/s http://janus.astro.umd.edu/astro/distance/
4.29 years
Why do we use Light Years? Because distances in space are too vast (big), miles and kilometers are too small to be used. Scientists measure the distances in space outside our solar system in light years (ly)
The Milky Way is the galaxy in which the Solar System is located. The Milky Way Galaxy is about 100,000 light years across http://www.youtube.com/watch?v=0fKBhvDjuy0&feature=player_embedded
One light-year is the DISTANCE that light travels in one year What is a Light Year? One light-year is the DISTANCE that light travels in one year
HOW FAR a Light Year is, If we are going to find out we need to know two things… The speed of light, measured in meters per second and The number of seconds in a year
What’s the fastest speed in the universe? - The Speed of Light What is the speed of light? (abbreviated “c”) 300,000,000 meters per second or 3 X 108 m/s
How Many Seconds in a Year? 60 seconds per minute X 60 minutes per hour X 24 hours per day X 365.25 days per year = the number of seconds per year 31.55 million
So How Far is a Light Year? 9,500,000,000,000,000 meters. This said out loud is.. That’s Nine Quadrillion, Five Hundred Trillion Meters
What is this in scientific notation? 9,500,000,000,000,000 meters. In scientific notation, this is 9.5 x 1015 m
Distance from the Earth Practice! Location Distance from the Earth Standard Form Scientific Notation Proxima Centauri 4.29 ly Center of the Milky Way 2.99 x 104 ly Andromeda 2,490,000 ly Coma Cluster of Galaxies 3.34 x108 ly Edge of the observable Universe 14,900,000,000 ly
More Practice! Location Distance from the Sun Standard Form Scientific Notation Mercury 57,910,000 km Earth 1.496 x 108 km Mars 2.279 x 108 km Saturn 1,426,730,000 km Pluto 5,906,380,000 km