- Earth - (noun) Saxon=Erda. Dirt or the planet on which we live.
- Terra - (noun) Latin.
- Terran - (adjective)
- Moon - (noun) From the Latin word Mensis (month).
- Luna - (noun) Latin.
- Lunar - (adjective)
- Terran equatorial diameter: 12,756km (<8000miles) - - Average radius = 6,371,000m
- Lunar equatorial diameter: 3475km (~earth/4)
- Earth mass:
- Moon mass: (0.01 X Mass of Earth)
- Earth's Average distance from Sol: 150,000,000km (93,000,000 miles)
- Moon's Average distance from Earth: 384,400km (250,000 miles)
- Orbits because of:
- Earth orbits around Sun:
- Moon orbits around Earth (Sidereal Period): 27 d 7 h 43.1 min
- Moon orbits around Earth (Synodic Period): 29 d 12 h 44.0 min
- Earth rotates:
- Moon rotates:
- Earth's Inclination: 23.5° to the plane of the Solar System
- Moon's Inclination: 5.145° to the ecliptic
- Earth Atmosphere:
- Moon Atmosphere:
- Gravity on Earth:
- Gravity on Moon:
Gravity (Newton & Einstein)
- Aristotle thought that heavier objects fell faster than lighter objects. He partially understood momentum, thinking that moving objects had a sort of moving energy. If a cannonball was flying through the air, it would continue to move in a straight line (he thought) until it ran out of energy. Then (he thought) it would fall straight down. Thus, according to Aristotle, projectiles always followed the path of a right triangle. The church taught these ideas until the end of the Renaissance.
- Galileo discovered/proved that Objects on Earth all fall at the same rate. g = -9.81m/s2 - - - TeacherTube Video of Dave Scott
- DesCartes & Kepler each had their own theories about planetary motion. Kepler figured out their true paths, but they were otherwise both wrong about gravity.
- Newton wrote equation to calculate gravitational force between and 2 obj. He figured out that gravity and inertia keep them in orbit.
- Newton's Law of Universal Gravitation (p263):
- where G is the constant of universal gravitation,
- the m's are the masses of the 2 objects, and r is the distance between them.
- Force is measured in Newtons
- Gravitational force is localized to the center of a spherical mass. (so to find your weight, we would need to know the radius and mass of the Earth.)
- 5. Einstein found the link between mass, gravity, velocity and time. Mass curves time-space, causing objects to fall into gravity wells.
We travel through 2 zones of high tides a day, because there are 2 tidal bulges that follow the Moon as the Earth rotates below it.
- Spring Tides-
- Neap Tides-
4 weeks, 8 phases position, West to East, orbit, Sun, Moon, Earth light, shadow, visible parts, reflection, rotation speed, ecliptic, The near side of the Moon is always turned toward the Earth. Position of Moon changes as goes around ---- in its orbit... causes different phases at different times. We only see part of the Moon that the Sun is shining on it.
- The moon has 8 phase positions that re-occur every four weeks. The phases of the moon are caused by its revolution around the earth, and the angle of the Sun's light as seen from our point of view. During the moon's orbit, we see changing amounts of the 51% of the moon that is illuminated. The moon roughly follows the ecliptic, rising in the East and setting in the West. However, since it is moving around the Earth about 12 degrees per day, it slowly moves across the sky, seeming to go backward every evening, until it is back at its starting point and in the same starting phase. The near side of the moon is always facing the earth, which shows each phase.
- 1. Solar Eclipses-
- 2. Lunar Eclipse-
Why do they last so long?
- Define Umbra, Penumbra, Partial eclipse
Origins of the Moon
Theories concerning the Origin of Luna
- Sister world formed at the same time of the same stuff (popular, but moon has no iron core)
- Parted at birth (“)
- Parted because of a collision much later (but could Earth have healed the wound?)
- Captured (but moon has similar water isotope content)
Why is the Moon so important to humans?
- Romance / Religion / Our closest neighbor, it is somehow our connection to the cosmos
- Launching platform / staging area / practice for exploring other places:
- gives a 2300mph boost to speed when launching from moon as opposed to earth
- lesser gravity means it's easier to escape
- let's use moon materials instead of earth materials!!!