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Pitt ASTRON 0087 - Exam 1 Study Guide

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ASTRON 0087 1st Edition Exam # 1 Study GuideChapter One: SpaceScientific 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 are some of the reasons why we continue to go into space, despite the expense?1. Knowledge: we want to know about other planets, if we’re alone in the universe, etc2. Technological advantages: all of our satellites are in space, we can map the earth from space, and we can forecast weather from space3. We want to prove that we’re the bestWhat kind of stuff is in space?Individual items: Stars (ball of gas); planet (a large object, made of either gas or rocks, that orbits a star); moon (rocky or icy chunk that orbits a planet); asteroid (small, rocky chunk that orbits a star); comet (small, icy chunk that orbits a star)Group Items: Solar system (a collection of the star and the planets and other objects that orbit it); star cluster (a group of stars that were created from the same cloud of gas at the same time);galaxy (an island of stars); universe (all of the matter and energy that exist)What kind of galaxy do we live in?The Milky Way Galaxy is a spiral galaxy that has a bulge in the middle that’s surrounded by a flatdisk. It’s about 100,000 light years across.What’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 is the process of the scientific method?Gather data => form theory => test theory => (if theory incorrect) gather more data and repeatCan a theory be proven to be true?No. A theory is never proven, only consistent with evidence that people can find. A theory CAN be proven false.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.What’s the prediction between a model prediction and a model concept?You can test model predictions, but you can’t test model concepts.Chapter Two: the Solar SystemWhat’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 itWhat are the two types of planets?Inner terrestrial planets (from Mercury until Mars) and outer Jovian planets (from Jupiter until Neptune)What are the characteristics of these types of planets?Terrestrial 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 are some of the features of asteroids?They have less than 1/10th the mass of a moon, are in orbit between Jupiter and Mars (2.1 AU to3.3 AU), are unusually shaped and fairly small, and are able to reflect sunlight. There are two types of asteroids: the C-type asteroids (75% of all asteroids) that have a lot of carbon, the S-type asteroids (15%) which have a lot of silicate/rock material, and M-type (10%) which have a lot of iron. The asteroids that cross paths with the Earth are called Apollo asteroids.What 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. It’s the distance changed when What did Copernicus do?Copernicus first proposed that the Sun is the center of the solar system, rather than the Earth. This allowed for an explanation of retrograde motion. Also, he proposed that planets have elliptical orbits.What did Galileo do?Galileo continued to say that the Sun was the


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