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Units of Measure. Earth-Moon Sizes. Earth Radius is 6,378 Km Using earth as 1. Moon Radius is 1,738 Km 0.27 ~1/4 radius. Earth-Moon Sizes. If the Earth were this ball, which of the others could be the Moon? This ball (Earth) ~ 16 cm Therefore Moon ~ 4 cm. Earth – Moon System.
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Earth-Moon Sizes • Earth • Radius is 6,378 Km • Using earth as 1 • Moon • Radius is 1,738 Km • 0.27 • ~1/4 radius
Earth-Moon Sizes • If the Earth were this ball, which of the others could be the Moon? • This ball (Earth) ~ 16 cm • Therefore Moon ~ 4 cm
Earth – Moon System How far away from Earth is the Moon? Take our model Earth and Moon and place them the distance away you think they should be…
Earth – Moon Distance • Distance from Earth to Moon • 384,400 Km • ~30 x Earth’s diameter • ~1.3 light seconds • Using our objects? • If Earth is ~ 16 cm • Distance (30 x 16cm) ~ 480 cm (5 m)
Sun – Earth System How does the size of the Earth compare to the Sun? If this was our Earth, how big would the Sun be?
Sun – Earth Sizes • Earth Radius • 6378 Km • Using Earth as 1 • If Earth is 16 cm • Sun Radius • 6.96 x 105 Km (696,000 Km) • ~109x Earth • ~ 2x Earth-Moon distance • The Sun 17 m diameter
Sun – Earth Distance • Distance from Earth to Sun • 1.5 x 108 Km (150,000,000 Km) • ~ 12,000x Size of Earth • ~400 x Earth-Moon distance • 500 light seconds, or 8.33 light minutes
Sun – Earth Distance • How far away from the Sun is the Earth? • Using our model Earth, how far do you think the Sun is? • Earth is 16 cm • About 2 Km from Sun to Earth • About the distance to Westville in New Haven
Earth’s Motions Orbital direction – revolves counterclockwise Orbital period – 365.26 days Rotational period – 1 day Tilt of rotation – 23.5 degrees
Moon’s Motions Orbital direction – counterclockwise Tilt of orbit – approx. 5 degrees Orbital period – 27.3 days (sidereal month) Rotational period – 27.3 days Synchronous rotation
Moon’s Formation • Impact theory of formation • Moon formed from the collision of Earth and a Mars-sized object • Likely theory, as Earth and Moon are composed of similar materials
More Theories of Moon Formation • Capture theory- Earth’s gravitational pull trapped a large object • Problems with this theory: • What would slow down this object? • Earth and Moon have similar materials in crust (expect them to be different if Moon had been captured)
Simultaneous Formation Theory- both formed at same time using same materials • Problems with this theory: • Does not explain why Earth has a mostly iron core (and Moon does not)