Notes

.Tides, Rotation, Libration, Phases, Eclipses
.High and low tides are caused by the moon. The moon's gravitational pull generates something called the tidal force.
.The tidal force causes Earth-and its water-to bulge out on the side closest to the moon and the side farthest from the moon.
.In real life, the Earth isn't a global ocean, covered in even layer of water. There are seven continents, and that land gets in the way. The continents prevent the water from perfectly following the moon's pull. That's why in some places, the difference between high and low tide isn't very big.
.On the side of Earth farthest from the moon, the moon's gravitational pull is at its weakest. At the center of Earth is is approximately the average of the moon's gravitational pull on the whole planet.
.The result of the tidal force is a stretching and squashing sides of Earth.
.The sun also causes tides, but less than it
.High-pressure weather systems can push down sea levels, low-pressure weather systems and cause floods and hurricanes.
.King tide = the highest predicted high tide of the year at a coastal location. It is above the highest water level reached at high ide on an average day.
.King tides are when the moon and the sun are pointed in one direction (Earth-Moon-Sun)
.First law: Orbit of a planet is an ellipse with Sun at one of two foci
.ellipse = Sum of distance from any point on an Ellipse to each focus is constant for all points
.ellipse = How can you use this definition to draw an ellipse? [hint: use paper, cardboard, 2 thumbtacks/pins, string, pencil]
.Planetary orbits in our solar system are also elliptical even though they look almost like concentric circles. Their foci are close in comparison to semi-major axis.
.Earth's semi-major axis is called 1 AU
.closest planet to sun = periphelion
.farthest planet = aphelion
.Second law: A line joining a planet and the Sun sweeps out equal area during equal intervals of time
.Third law: (orbital Period)^2 ∝ (semi-major axis)^3