ASTRON 0087 1st EditionFinal Exam Study Guide Chapters: 1 - 12CHAPTER ONE:Scientific Notation:What are the SI Units? How do they relate to the Imperial System?SI Units, or Systeme International d’Unites, include: meters - m (use instead of feet for length), kilograms - kg (use instead of pounds for mass), seconds - s (for time), and Kelvin - K (use instead of degrees Fahrenheit for temperature). SI Units are part of the metric system.What is temperature?Temperature is the measure of average kinetic energy in random motions. The lowest kinetic energy state is 0 K, which is when there is no motion at all. Water freezes at 273 K and boils at 373 K. What is an Astronomical Unit (AU)?The Astronomical Unit is the distance between the Earth and the Sun (1.5 x 10^11 = 1 AU). It is used as a unit of measurement in order to measure the distance between planets.Does a light year measure time or distance?A light year measures time, not distance. It is the distance that light travels in a year. (Light travels at 3.0 x 10^5 km/s)How old is the universe?13.7 billion years old, give or take 130,000 yearsWhat’s the composition of the universe?The universe is mostly dark energy (energy associated with space), since it makes up 72% of the composition of the universe. The rest is made up of dark matter (23%) and atoms (4.6%).Of the atoms, 70% are hydrogen, 28% are helium, and 2% are metals.What’s the gravity theory?(a) Gravity holds the sun together despite the forces inside the sun that are attempting to push it apart(b) Gravity is the reason why things orbit around the Sun(c) The Earth and Moon’s gravity causes the ties.What’s Newton’s law of gravity?Gravity has invisible lines of force that cause masses to pull on each other.What’s Einstein’s Theory of General Relativity?Large masses cause space and time to be curved. As a result, everything that is smaller than these masses will follow a natural, curved route around them.CHAPTER TWO:What’s the definition of a planet?1. It has to orbit around the sun.2. It has to have enough mass in order to stay in a vaguely round shape (hydrostatic equilibrium).3. It has to have “cleared the area” around its orbit, which means that it’s gotten rid of all of the smaller objects around it by either destroying them or causing them to join with itTerrestrial Planets (Mercury, Venus, Earth,Mars)Jovian Planets (Jupiter, Saturn, Uranus,NeptuneCloser to the Sun Farther from the sunFairly small LargerLower Mass Greater MassSlower rotation (period is about a day) Faster rotation (period much less than a day)Doesn’t have rings Has ringsHigher density Lower densityMostly made of solid material Mostly made of gaseous material or liquidAtmosphere is thin Atmosphere is denseNot a lot of moons Lots of moonsWhat causes a meteor shower?A meteor shower is caused when a comet (basically a dirty snowball) gets close enough to earthso that its tail, which is made of debris, gets burnt up in our atmosphere, causing streaks across the sky. The tail of a comet always points away from the sun because of the sun’s radiation.What is retrograde motion?Retrograde motion is the apparent east-west motion of other planets so that they look as though they are revolving in a different direction than all of the other planets in the solar system. The reason for retrograde motion is because the orbiting cycles of the Earth and Mars are different. The Earth orbits more quickly, so it appears to overtake Mars in its orbiting cycle, causing it to pause and then seem to be going backwards. Once Earth passes the planet, it will once again appear to be moving normally.What’s going on with parsecs and parallax?A parsec is the distance at which an object shows the parallax of one arcsecond. Parallax is when something looks like it changed its position because you changed your position.An arcsecond is 1/360th of a degree.Basically, a parsec is the parallax of one arcsecond. Famous Dudes Covered in Chapter 2:1. Copernicus – first to say that the planets rotated around the run, not Earth; also proposed that planets have elliptical orbits.2. Galileo – actually said that the Earth rotated the sun, that there were waaay more stars than we originally thought, that the moon had craters and mountains, and that 4 moons orbited Jupiter3. Kepler – developed three laws of planetary motion:a. Every planet has an elliptical orbit and the sun is at one foci (the other focus isempty).b. A planet moves along its elliptical path with a speed that changes in such a waythat a line from the planet to the Sun sweeps out equal areas in equal intervals oftime. (Basically, the Earth orbits more quickly when it is closer to the Sun andmore slowly when it is farther away from the Sun).c. a = semi-major axis; p = orbital perioda^3 = p^2 OR a^3/p^2 = constant OR (a^3/axis of the earth = p^2/orbital periodof the Earth). Axis of the earth can equal 1 AU and the orbital period of the earthcan equal 1 year or 365 days. Briefly give some characteristics of planetary motion:a. all planetary orbits are ellipses, but they’re practically circularb. all of the planets revolve around the sun in a counterclockwise directionc. all of the elliptical paths are in the same planed. most planets rotate counterclockwise in their own axis (except Mercury and Uranus)What’s inclination?The inclination of a planet’s orbit is the angle between the plane of a planet’s orbit and theplane of Earth’s orbit (known as the ecliptic plane).What’s obliquity?Obliquity is the angle between the ecliptic orbit and the celestial equator on a celestial sphere.CHAPTER THREEWhich lines are latitude and which lines are longitude?The lines that run in the same direction as the equator (horizontally) are latitude and lines that run parallel to a line that runs through the North and South poles are longitude.What’s triangulation (when talking about the GPS system)?Triangulation is when three (or more) GPS satellites are used to pinpoint your location. You can think of it as three satellites, each with a circle of area that they can detect. Wherever the three nearest satellites to your position have those circles overlap is the exact location to where you are. If you need an object that is not on the surface on the earth, you need a fourth satellite. A fourth satellite can also be used to calibrate the time.What’s a zenith? A nadir? The horizon?The zenith the point that is directly above you. The nadir is the point directly