| Term | Definition |
|---|
| Earth unit | the diameter of the Earth -- 12,756km |
| planet | round, orbits the Sun, has cleared neighborhood around its orbit |
| astronomical unit | distance from Earth to Sun = 93 million mi |
| singularity | the point in which universe existed that was infinitely dense and hot and took up zero space, time didn't exist |
| Fate of Universe - 3 options | 1) continue expansion forever - eventually stars die, cold & dark 2) expansion slows to a stop - finite universe 3) contracts - singularity forms again |
| Titius Bode Law | Law stating that each planet is ~2 times as far away from Sun as the next closest planet |
| asteroid belt | between Mars & Jupiter, could have once been a planet that was blown up OR a planet that never formed |
| nebular hypothesis | used to explain how solar system came to be |
| supernova | sun's outer forces are fueled by H & He, inner forces are gravity. When H & He run out, gravity is the sole acting force --> pressure gets so intense that heavier elements fuse, then star explodes out |
| nebula | giant cloud of gas and dust |
| conservation of angular momentum | mass x width x velocity (figure skater/Dennis) |
| condensation nuclei | microscopic platform which a gas can condense around |
| planetesimals | object during planetary growth - 100m-10km in size |
| planetary embryo | massive object in space, starting to clear orbit |
| gravitational focusing | planets clearing debris in distances between & within orbits by drawing material in to planet |
| age of Earth | 4.567 billion years |
| differentiation | lighter materials rise to top, denser sink to bottom during planet formation |
| planetary accretion | gradual growth of planet by collision & sticking |
| Tunguska Event | 1908 in ____, Siberia - giant fireball decimates 20mi in diameter of forest. - should have a ______-sized asteroid event every 100 years |
| White Nights | 3 days following Tunguska Event, in Northern Europe -- sun on other side of Earth reflecting from the massive dust cloud that moved over to N Europe |
| Meteor Crater, AZ | first site to be identified as an asteroid impact |
| asteroids | travel at ~60,000mph --> ____ is vaporized by heat & pressure // hopefully will break up as they go through atmosphere to form a teardrop pattern on ground |
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