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1.2 Size and Scale

Pre-Lecture Reading 1.2

Video Lecture

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Size and Scale (24:45)

Supplementary Notes

Speed of Light (c)

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c = 3 × 10⁸ m/s
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c = 3 × 10⁵ km/s

Light-Year (ly)

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1 ly is the distance that light travels in 1 yr.

( 1 )

distance = speed × time

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distance = 1 ly speed = c time = 1 yr distance = speed × time
1 ly = c × 1 yr
≈ (3 × 10⁵ km/s) × (π × 10⁷ s)
≈ 10¹³ km
= 10 trillion km
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distance to nearest star = 4.3 ly

Absolute Size vs. Relative Scale

Exercises

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Experiment with Google Earth.
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View Powers of Ten with Morgan Freeman (8:35).
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Experiment with Interactive Powers of Ten.

Assignment 1

Do Question 1.