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Measuring Distances in Space. The Light-Year (ly). Light-year (ly). distance light travels in one year. Reminders. Light travels in a straight line. The speed of light is 300,000 km/s The sun is 150 million km away By car @ 100 kph, it would take us 165 years to get to the sun
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Measuring Distances in Space The Light-Year (ly)
Light-year (ly) distance light travels in one year
Reminders... • Light travels in a straight line. • The speed of light is 300,000 km/s • The sun is 150 million km away • By car @ 100 kph, it would take us 165 years to get to the sun • By 747 @ 600 kph, 27.3 years • By shuttle @ 28,000 kph, 215 days • By Apollo @ 53,000 kph, 113 days • By light speed, it would take 8 minutes
Next Closest Star • Proxima Centauri • 4.3 ly away • If it went supernova today… • You would see it at graduation * Takes light 4.3 years to get here!
The Milky Way Our galaxy… • ~ 7,000 ly thick • ~ 100,000 ly diameter • Light takes 100,000 years to travel from one side to the other • Earth about 26,000 ly from the core
Your Turn… • Just how far does light travel in 1 year? • Your group will need paper & pencil (you may use a calculator) • With your team, calculate the distance to Proxima Centauri, 4.3 ly away…raise your hand when you think you are done and I will check it. • HINT: need to use Speed of light and time