Tides and Tidal Forces

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Tides and Tidal Forces
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Near Satellites Orbit Faster
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What If Satellites Are Tethered?
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The Tension Is Real
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There are Two Tidal Bulges on Earth
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Both Moon and Sun Cause Tides
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Tides on the Real Earth
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Tidal Friction
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Tides Affect Earth and Moon
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Tides and the Earth-Moon System

• Moon retreating at 4 cm/yr
• Day currently lengthening by 2 sec/100,000 yr
• Fossil organisms and some rocks preserve tidal
  records
• 600 million years ago
• Day was 22 hours long
• 400 days/year
• Moon 13,000 km closer
• Rate of change not constant

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Tides and Planets

• All satellites are locked to their parent planets
• Large tides can heat planetary interiors
• Tidal forces change orbital eccentricity
• Most satellites
• Planet rotation slows
• Moon moves outward
• Can leak away (Deimos)
• Retrograde Satellites
• Satellite moves inward (Triton)