(so far, this is a work-in-progress. Keep checking back. Hopefully it'll be in fairly final form by the time we begin class)
* Science is the art of asking Nature herself how she works. The steps: Observe, make hypothesis, find logical observable implications, and search for evidence these implications are in the real world.
* Occam's Razor - simpler explanations have a better chance of being true. Carl Sagan's corollary - extraordinary claims require extraordinary evidence.
* Gravity pulls on the near side stronger than the far side, so object is stretched - the "tidal force". The bigger the object, the more tidal stretching it will feel.
* For an isolated system, the total angular momentum cannot change; it can shift around, but not change. Examples of approximately isolated systems: planets and their moons, binary stars, individual galaxies far from other galaxies.
* More massive objects cool slower. Example: more massive planets hold more of their original heat, and so have thinner crusts. Original heat is mostly due to impacts as the "solar nebula" material fell onto growing planets.
* Planetary atmospheres: At a given temperature, lighter elements (hydrogen and helium especially) move faster and escape the gravity into space more easily: Only the cold outer planets were able to retain hydrogen and helium. Since H and He comprise the vast majority of the original material, means the outer planets are much more massive than the inner planets.
* Stars: the Main Sequence is made of up of stars fusing hydrogen into helium in their core, by definition.
* Stars: the lower the mass, the more common they are, the dimmer they are, and the longer they live.
* Stars: On the Main Sequence, the lower the mass, the cooler the star.
* Red Giants: Old stars that have exhausted hydrogen in core (don't worry about yellow giants or any other color giants. Regular astronomers call them all "red giants" and so will I)
* Stellar corpses are one of 3 things: White dwarfs (low mass stars end up here), Neutron Stars (massive star supernovae produce theses), Black Holes (if the supernova remnant has more than 3 solar masses, you get a black hole)
* Only hydrogen and helium emerged from the Big Bang. Lithium-5 and beryllium-8 are not stable. Only stars, with their dense hot cores, can get past this road block and build carbon and the rest of the periodic table of chemical elements.
* Light travels at 300,000 km/sec so looking farther out in space means looking back further in time. Farther things are seen at earlier times, when the light left the object.
* Galaxies: the lower the mass, the more common they are.
* Elliptical galaxies made mostly by galaxy collisions. Collisions between galaxies produce an irregular galaxy, which settles into a single merger that is an elliptical galaxy.
* Masses of "bee swarm" objects like elliptical galaxies and galaxy clusters are measured by their velocity dispersion.
* Evidence the Big Bang really happened: The Cosmic Microwave Background radiation, from when the universe cooled to 3,000K and hydrogen atoms could first form out of the hot ionized primordial gas. Also, the abundance of the elements making up the first stars match precisely that prediced by a hot Big Bang beginning.
* Universe expands like a raisin cake, uniformly in all directions, making all galaxies see the same Hubble Law (V=HD) expansion pattern. Locally, overdense regions can gravitationally halt their expansion and recollapse into a galaxy cluster.
* Larger scale, gravity pulls overdense regions into sheets, filaments and clusters as the universe evolves. Large scale structure is best described as filamentary.
* The universe is 13.7 billion years old, and it's structure is remarkably consistent with an origin described by Inflation, whereby the universe began with zero total energy and "inflated" by roughly 1060 before resuming a normal Hubble expansion. Universe is likely infinite in extent.
* Inflation predicts a universe of exactly zero total energy, now confirmed by observations to within 1%. And it predicts the statistical pattern of density fluctuations which are observed in the early universe as shown by the Cosmic Microwave Background radiation.
* The universe today is 70% "dark energy" (we're still pondering it's nature), 25% Cold Dark Matter (it looks to be a WIMP (weakly interacting massive particle). Nature of this particle is currently unknown, but we're making good progress in narrowing it down and developing technology to directly detect it and identify it. And, the last 5% is ordinary matter (everything you see around you and see directly elsewhere in the universe).
* Life must be complex to have the properties we call "alive", requires it be made of carbon, the only atom capable of building complex molecules. Altering the known laws of physics even a little usually leads to a universe in general unable to evolve any form of complexity - life. Therefore, the existence of life itself argues that there is more than one "universe". Instead a Multiverse. More directly, the Inflationary mechanism is expected to be producing universes all the "time", birthing with their own space, their own time, their own laws of physics, and unobservable from our own universe. If this is in fact true, it makes our existence easy to understand - we're of course in one of the rare universes which is capable of producing complex structures - life - we're "self selected".