“Gravitation is not responsible for people falling in love.” Einstein

Baseline: The Earth and Moon

200 Myrs 3.5 Gyrs 4-4.5 Gyrs

How old is the Earth, as a whole. Current estimate: 4 How old is the Earth, as a whole? Current estimate: 4.6 billion years old. This is the estimate for the age of our solar system as a whole.

The Earth: Multi-colored, round, massive, solid rocky planet with a thin blue-water ocean and white-cloud atmosphere. Green/brown land masses, white polar caps (spin axis nearly aligned with orbital axis) with water/wind weathering, plate tectonics, and volcanoes.

The Moon: Single color/composition massive, round, rock in space The Moon: Single color/composition massive, round, rock in space. Solid, heavily cratered surface, no obvious atmosphere, with one side (tidally) locked to the Earth.

Tidal locking. Smaller things will have only 1 side facing larger things.

What about the structure (insides) of the Earth?

What about the insides? If we haven't directly sampled it, how do we know what is at the center of the Earth, or the Moon?

The structure of the Earth using seismology

The Earth's structure: Density=5.5g/cc

What is the Earth is made of? Atmosphere: 78% Nitrogen, 21% Oxygen, 1% Argon, 0.03% CO2 Oceans: Water of course, but also salt (Sodium) and Carbon Crust: Oxygen, Silicon, Aluminium, Iron, Calcium, Sodium Mantle: Silicates and Magnesium and Iron Outer Core (liquid): Mostly Iron, some Nickel (4%) and 10% other (mostly Oxygen). Inner Core (solid): Mostly Iron, same as the outer core.

What is the Earth is made of?What does this tell us? Crust: Oxygen, Silicon Mantle: Silicates and Magnesium Outer Core (liquid): Mostly Iron Inner Core (solid): Mostly Iron

What does this tell us? That the Earth is differentiated! The heavy stuff settled to the center. This means the Earth must at one time have been completely molten (liquid).

Question 1: The length of time it takes the Earth to orbit the Sun is called what? A) A day B) A month C) A year D) A Decade E) A millenia

Question 2: What is the ecliptic? A) When the Moon passes in front of the Sun B) When the Sun passes in front of the Moon C) The path of the Earth’s orbit around the Sun. D) Both A and B above.

Question 3: What is the phase of the Moon during a lunar eclipse? A) New B) Full C) 1st Quarter D) 3rd Quarter E) Gibbous

Question 4:What is a sidereal day? A) A day according to the stars B) A day according to the Sun C) A year according to the stars D) A day which is 4 minutes shorter than night. E) The last day on Earth when the Sun expands and consumes us in blazing fire.

Question 5: How old is the surface in the image? A) <few Myrs: no craters visible. B) 200 Myrs: only 1 or 2 craters visible. C) 2 Gyrs: plenty of craters, but not saturated, like the lunar mare. D) 4.5 Gyrs: saturated with craters.

Question 6: For us, the Sun at noon will always be in what direction? A) North B) East C) West D) South E) Straight overhead

Question 7: The last sentence of the statement is what part of the scientific method? A) Observations B) Theory C) Prediction D) Test of prediction E) Confirm/refute/modify prediction

Question 8: Why are there so few craters on the Earth? A) Erosion and resurfacing erases them. B) The Moon protects us from most meteorites. C) Our atmosphere protects us. D) The Earth just has not been hit much. Good fortune smiles upon us. E) The Earth is good at dodging.

Question 9: On Copernicus crater, how often does the Earth set? A) Every 27 days B) Every 29 days C) Once every year D) Never, it is always in view. E) Always, it is never in view.

Question 10: Color variety in a surface can mean what? A) Various compositions B) Changes in temperature C) Changes in altitude D) All of the above E) None of the above

Question 11: Why do we sometimes have total and other times have annular eclipses? A) The Moon’s size changes with seasons. B) Tides from Earth change the Moon’s size. C) The Moon’s orbit is not perfectly round, so sometimes it is slightly closer or further away. D) During summer, the Sun is larger, and therefore you cannot have a total eclipse.

All done. I’ll collect your papers All done. I’ll collect your papers. Please pass them to the aisle on the right side (your right side) of the room. Be sure your row letter is on them, for when they are passed back, one week from today. Please tear off rough edges.

If you took a picture of the Sun every day at noon If you took a picture of the Sun every day at noon. You would get something like this.

Earth's Seasons We all know that summers are hotter than winters- why?

Seasons Determined by: Length of day (longer day, more Sunlight to provide heat) How direct the sunlight hits the surface. How much atmosphere light has to go through. Atmosphere refracts light (especially blue, thus the color of the sky) The Sun appears orange at sunset because all the blue light is refracted, leaving only the red part.

Sunlight is made up of all the colors of the rainbow Sunlight is made up of all the colors of the rainbow. When combined, this produces white light. But Earth's atmosphere refracts (deflects) certain colors more than others. Thus the Sun appears yellow and the sky appears blue.

Terms Equinox: Sun is over the equator Solstice: Sun is as far north/south as it gets. (23.5 degrees) Ecliptic: Plane in which the Earth orbits the Sun