DOCSLIB.ORG

Study Guide for the Midterm

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Study Guide for the Midterm Experience Astronomy Study Guide for the Midterm The Purpose of Astronomy Astrology is focused the meanings of heavenly movements (predicting what will happen here on Earth, impacting things on Earth, or in:luencing our personality). Astronomy, however, is a scienti:ic study of the sky. The irst chapter of Genesis says God created the stars for very practical reasons: • to give us light on the Earth • to separate day from night • to help us create calendars that guide our different seasons of planting, harvesting, and celebrating, and to help us mark different years so we could keep records of history • to help us use the signs in the sky to navigate around and :ind our way The Celestial Sphere Celestial Sphere – a spherical representation or map of the :ixed stars we see in the sky; divided into 88 regions called constellations Celestial Poles - the axis of the Earth points at these northernmost and southernmost points on the celestial sphere Celestial Equator - if the Earth’s equator was projected out into space, the line it would make on the celestial sphere is the celestial equator Ecliptic - the path the sun takes through the celestial sphere over the course of a whole year; it is tilted in respect to the celestial equator because the Earth’s axis is tilted 23.5° The Direction of Spin - Looking down on the north pole, the Earth spins counterclockwise. Looking straight on at the Earth, it spins in an Eastward direction. This means the celestial sphere overhead moves in a westward direction from our perspective on Earth. Latitude Lines - a geographic coordinate that indicates the north-south position of a point on the Earth, ranging from 0° at the Equator to 90° at the North and South poles; your latitude position determines what part of the celestial sphere you see (for instance, standing at 90°N, the north pole, means the North Celestial Pole will be at your zenith) !1 Terms Absolute Magnitude - how bright a star really is if all stars were the same distance from us A.M. - Ante Meridiem, meaning before the middle of the day Apparent Magnitude - how bright a star appears in our sky The Arctic Circle - the latitude line where the sun doesn’t set on the summer solstice Autumnal (Fall) and Vernal (Spring) Equinoxes - the two days of the year when the sun rises and sets on the celestial equator, making an equal amount of daylight and nighttime Axis - the line around with the Earth (or any planetary body) rotates Day - the amount of time it takes for the Earth to spin on its own axis one time The Galilean Moons - four largest moons of Jupiter: Europa, Io, Callisto, and Ganymede Geocentric Model – a model or understanding of the universe where the Earth is at the center, and the sun, moon, planets and stars revolve around the Earth Horizon – from your perspective, the place where the sky meets the land Jupiter - a planet named after king god of the Romans; the most massive, fastest spinning planet in the solar system, with more moons than any other planet The Land of the Midnight Sun - a name for the region north of the Arctic circle because the sun doesn’t set during the summer months Light Year – the distance light travels in a year (about 5.8 trillion miles) Meridian - the line on the celestial sphere going from due south, straight over your head through the zenith, to due north; it means “middle of the day” The Milky Way - a cloudy band circling the celestial sphere which is actually about 100 billion distant stars in our Milky Way Galaxy Planet - a word meaning “wandering star”; the :ive classical planets are Mercury, Venus, Mars, Jupiter, and Saturn P.M. - Post Meridiem, meaning after the middle of the day Polar Night - the phenomenon where the sun doesn’t rise north of the Arctic circle during the winter months !2 Retrograde motion - when a planet stops going eastward against the background stars, turns around, and starts moving westward Saturn - a planet named after the Roman god of agriculture and wealth; known for its rings Summer solstice - from the perspective of the Northern hemisphere, the day of the year when the Sun rises and sets at the northernmost place on the horizon, making a large arc through the sky (the day with the most amount of sunlight) Terminator - the line on the surface of the globe where the night side of the Earth meets the day side Titan - the largest moon of Saturn, known for its atmosphere and liquid lakes The Tropic of Cancer - the latitude line where the sun is at the zenith at high noon on the summer solstice The Tropic of Capricorn - the latitude line where the sun is at the zenith at high noon on the winter solstice The Tropics - The region between the Tropic of Cancer and the Tropic of Capricorn Winter solstice - from the perspective of the Northern hemisphere, the day of the year when the Sun rises and sets at the southernmost place on the horizon, making a shallow arc through the sky (the day with the least amount of sunlight) Zenith – from your perspective, the part of the celestial sphere that is right over your head People Aristotle • one of the most famous philosophers of all time • argued for a spherical shape to the Earth • argued for a geocentric model to the universe Aristarchus • :irst person we know about who proposed a heliocentric model of the universe Ptolemy • Greek astronomer • created a catalogue of 48 constellations which much later became the basis for our 88 constellations • followed a geocentric model, creating a mathematical system for predicting the movements of the planets and the stars !3 Copernicus • resurrected the idea of a sun-centered model in the middle ages Kepler • discovered the three laws of planetary motion Galileo • one of the irst to use a telescope to observe the sky • discovered the four largest moons of Jupiter Constellations and Stars Polaris - meaning “pole star”; this star in Ursa Minor is commonly called the North Star The Zodiac - 12 traditional constellations that touch the ecliptic: Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpius, Sagittarius, Capricornus, Aquarius, and Pisces The Summer Triangle - an asterism made up of the three very bright stars Vega, Deneb, and Altair Fomalhaut - meaning “mouth of the :ish”; a 1st magnitude star in Pisces Austrinus Pollux and Castor - two bright stars in the constellation Gemini Aldebaran - a 1st magnitude star in the constellation Taurus Betelgeuse and Rigel - two 1st magnitude stars in the constellation Orion Aquila the eagle !4 Lyra the lyre Cygnus the swan !5 Hercules Pisces Austrinus the southern =ish Aquarius the Water Bearer !6 Pisces the =ish Pegasus the =lying horse Andromeda !7 Perseus Cassiopeia Gemini the twins !8 Ursa Major the big bear Taurus the bull !9 Aries the ram Capricornus the sea-goat Orion the hunter !10.
Load more

Recommended publications
  • Constructing a Galactic Coordinate System Based on Near-Infrared and Radio Catalogs
    A&A 536, A102 (2011) Astronomy DOI: 10.1051/0004-6361/201116947 & c ESO 2011 Astrophysics Constructing a Galactic coordinate system based on near-infrared and radio catalogs J.-C. Liu1,2,Z.Zhu1,2, and B. Hu3,4 1 Department of astronomy, Nanjing University, Nanjing 210093, PR China e-mail: [jcliu;zhuzi]@nju.edu.cn 2 key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210093, PR China 3 Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008, PR China 4 Graduate School of Chinese Academy of Sciences, Beijing 100049, PR China e-mail: [email protected] Received 24 March 2011 / Accepted 13 October 2011 ABSTRACT Context. The definition of the Galactic coordinate system was announced by the IAU Sub-Commission 33b on behalf of the IAU in 1958. An unrigorous transformation was adopted by the Hipparcos group to transform the Galactic coordinate system from the FK4-based B1950.0 system to the FK5-based J2000.0 system or to the International Celestial Reference System (ICRS). For more than 50 years, the definition of the Galactic coordinate system has remained unchanged from this IAU1958 version. On the basis of deep and all-sky catalogs, the position of the Galactic plane can be revised and updated definitions of the Galactic coordinate systems can be proposed. Aims. We re-determine the position of the Galactic plane based on modern large catalogs, such as the Two-Micron All-Sky Survey (2MASS) and the SPECFIND v2.0. This paper also aims to propose a possible definition of the optimal Galactic coordinate system by adopting the ICRS position of the Sgr A* at the Galactic center.
    [Show full text]
  • Constellations with Prominent Stars That Can Be Found Near the Meridian at 10 Pm on January 15
    ONSTELLATIONS C Altitude Ruler The rotation of the Earth on its axis causes the stars to rise and set each evening. In addition, the orbit of the Earth around the Sun places different regions of the sky in our Horizon night-time view. The PLANISPHERE is an extremely useful tool for finding stars and 10 constellation in the sky, depicting not only what is currently in the sky but it also allows the 20 prediction of the rising and setting times of various celestial objects. 30 THE LAYOUT OF THE PLANISPHERE 40 50 The outer circumference of the dark blue circular disk (which is called the star wheel) you’ll notice that the wheel is divided into the 12 months, and that each month is divided into 60 individual dates. The star wheel rotates about the brass fastener, which represents the 70 North Celestial Pole. The frame of the planisphere has times along the outer edge. 80 Holding the planisphere on the southern corner you'll see "midnight" at the top. Moving Zenith counterclockwise, notice how the hours progress, through 1 AM, 2 AM, and so on through "noon" at the bottom. The hours then proceed through the afternoon and evening (1 PM, 2 PM, etc.) back toward midnight. Once you have the wheel set properly for the correct time and day, the displayed part represents what you see if you stand with the star and planet locator held directly over your head with the brass fastener toward the north. (Notice that the compass directions are also written on the corners of the frame.) Of course, you don't have to actually stand that way to make use of the Star and Planet Locator--this is just a description to help you understand what is displayed.
    [Show full text]
  • Earth-Centred Universe
    Earth-centred Universe The fixed stars appear on the celestial sphere Earth rotates in one sidereal day The solar day is longer by about 4 minutes → scattered sunlight obscures the stars by day The constellations are historical → learn to recognise: Ursa Major, Ursa Minor, Cassiopeia, Pegasus, Auriga, Gemini, Orion, Taurus Sun’s Motion in the Sky The Sun moves West to East against the background of Stars Stars Stars stars Us Us Us Sun Sun Sun z z z Start 1 sidereal day later 1 solar day later Compared to the stars, the Sun takes on average 3 min 56.5 sec extra to go round once The Sun does not travel quite at a constant speed, making the actual length of a solar day vary throughout the year Pleiades Stars near the Sun Sun Above the atmosphere: stars seen near the Sun by the SOHO probe Shield Sun in Taurus Image: Hyades http://sohowww.nascom.nasa.g ov//data/realtime/javagif/gifs/20 070525_0042_c3.gif Constellations Figures courtesy: K & K From The Beauty of the Heavens by C. F. Blunt (1842) The Celestial Sphere The celestial sphere rotates anti-clockwise looking north → Its fixed points are the north celestial pole and the south celestial pole All the stars on the celestial equator are above the Earth’s equator How high in the sky is the pole star? It is as high as your latitude on the Earth Motion of the Sky (animated ) Courtesy: K & K Pole Star above the Horizon To north celestial pole Zenith The latitude of Northern horizon Aberdeen is the angle at 57º the centre of the Earth A Earth shown in the diagram as 57° 57º Equator Centre The pole star is the same angle above the northern horizon as your latitude.
    [Show full text]
  • Educator's Guide: Orion
    Legends of the Night Sky Orion Educator’s Guide Grades K - 8 Written By: Dr. Phil Wymer, Ph.D. & Art Klinger Legends of the Night Sky: Orion Educator’s Guide Table of Contents Introduction………………………………………………………………....3 Constellations; General Overview……………………………………..4 Orion…………………………………………………………………………..22 Scorpius……………………………………………………………………….36 Canis Major…………………………………………………………………..45 Canis Minor…………………………………………………………………..52 Lesson Plans………………………………………………………………….56 Coloring Book…………………………………………………………………….….57 Hand Angles……………………………………………………………………….…64 Constellation Research..…………………………………………………….……71 When and Where to View Orion…………………………………….……..…77 Angles For Locating Orion..…………………………………………...……….78 Overhead Projector Punch Out of Orion……………………………………82 Where on Earth is: Thrace, Lemnos, and Crete?.............................83 Appendix………………………………………………………………………86 Copyright©2003, Audio Visual Imagineering, Inc. 2 Legends of the Night Sky: Orion Educator’s Guide Introduction It is our belief that “Legends of the Night sky: Orion” is the best multi-grade (K – 8), multi-disciplinary education package on the market today. It consists of a humorous 24-minute show and educator’s package. The Orion Educator’s Guide is designed for Planetarians, Teachers, and parents. The information is researched, organized, and laid out so that the educator need not spend hours coming up with lesson plans or labs. This has already been accomplished by certified educators. The guide is written to alleviate the fear of space and the night sky (that many elementary and middle school teachers have) when it comes to that section of the science lesson plan. It is an excellent tool that allows the parents to be a part of the learning experience. The guide is devised in such a way that there are plenty of visuals to assist the educator and student in finding the Winter constellations.
    [Show full text]
  • 2. Descriptive Astronomy (“Astronomy Without a Telescope”)
    2. Descriptive Astronomy (“Astronomy Without a Telescope”) http://apod.nasa.gov/apod/astropix.html • How do we locate stars in the heavens? • What stars are visible from a given location? • Where is the sun in the sky at any given time? • Where are you on the Earth? An “asterism” is two stars that appear To be close in the sky but actually aren’t In 1930 the International Astronomical Union (IAU) ruled the heavens off into 88 legal, precise constellations. (52 N, 36 S) Every star, galaxy, etc., is a member of one of these constellations. Many stars are named according to their constellation and relative brightness (Bayer 1603). Sirius α − Centauri, α-Canis declination less http://calgary.rasc.ca/constellation.htm - list than -53o not Majoris, α-Orionis visible from SC http://www.google.com/sky/ Betelgeuse https://en.wikipedia.org/wiki/List_of_Messier_objects (1758 – 1782) Biggest constellation – Hydra – the female water snake 1303 square degrees, but Ursa Major and Virgo almost as big. Hydrus – the male water snake is much smaller – 2243 square degrees Smallest is Crux – the Southern Cross – 68 square degrees Brief History Some of the current constellations can be traced back to the inhabitants of the Euphrates valley, from whom they were handed down through the Greeks and Arabs. Few pictorial records of the ancient constellation figures have survived, but in the Almagest AD 150, Ptolemy catalogued the positions of 1,022 of the brightest stars both in terms of celestial latitude and longitude, and of their places in 48 constellations. The Ptolemaic constellations left a blank area centered not on the present south pole but on a point which, because of precession, would have been the south pole c.
    [Show full text]
  • Celestial Coordinate Systems
    Celestial Coordinate Systems Craig Lage Department of Physics, New York University, [email protected] January 6, 2014 1 Introduction This document reviews briefly some of the key ideas that you will need to understand in order to identify and locate objects in the sky. It is intended to serve as a reference document. 2 Angular Basics When we view objects in the sky, distance is difficult to determine, and generally we can only indicate their direction. For this reason, angles are critical in astronomy, and we use angular measures to locate objects and define the distance between objects. Angles are measured in a number of different ways in astronomy, and you need to become familiar with the different notations and comfortable converting between them. A basic angle is shown in Figure 1. θ Figure 1: A basic angle, θ. We review some angle basics. We normally use two primary measures of angles, degrees and radians. In astronomy, we also sometimes use time as a measure of angles, as we will discuss later. A radian is a dimensionless measure equal to the length of the circular arc enclosed by the angle divided by the radius of the circle. A full circle is thus equal to 2π radians. A degree is an arbitrary measure, where a full circle is defined to be equal to 360◦. When using degrees, we also have two different conventions, to divide one degree into decimal degrees, or alternatively to divide it into 60 minutes, each of which is divided into 60 seconds. These are also referred to as minutes of arc or seconds of arc so as not to confuse them with minutes of time and seconds of time.
    [Show full text]
  • Positional Astronomy Coordinate Systems
    Positional Astronomy Observational Astronomy 2019 Part 2 Prof. S.C. Trager Coordinate systems We need to know where the astronomical objects we want to study are located in order to study them! We need a system (well, many systems!) to describe the positions of astronomical objects. The Celestial Sphere First we need the concept of the celestial sphere. It would be nice if we knew the distance to every object we’re interested in — but we don’t. And it’s actually unnecessary in order to observe them! The Celestial Sphere Instead, we assume that all astronomical sources are infinitely far away and live on the surface of a sphere at infinite distance. This is the celestial sphere. If we define a coordinate system on this sphere, we know where to point! Furthermore, stars (and galaxies) move with respect to each other. The motion normal to the line of sight — i.e., on the celestial sphere — is called proper motion (which we’ll return to shortly) Astronomical coordinate systems A bit of terminology: great circle: a circle on the surface of a sphere intercepting a plane that intersects the origin of the sphere i.e., any circle on the surface of a sphere that divides that sphere into two equal hemispheres Horizon coordinates A natural coordinate system for an Earth- bound observer is the “horizon” or “Alt-Az” coordinate system The great circle of the horizon projected on the celestial sphere is the equator of this system. Horizon coordinates Altitude (or elevation) is the angle from the horizon up to our object — the zenith, the point directly above the observer, is at +90º Horizon coordinates We need another coordinate: define a great circle perpendicular to the equator (horizon) passing through the zenith and, for convenience, due north This line of constant longitude is called a meridian Horizon coordinates The azimuth is the angle measured along the horizon from north towards east to the great circle that intercepts our object (star) and the zenith.
    [Show full text]
  • Astronomy I – Vocabulary You Need to Know
    Astronomy I – Vocabulary you need to know: Altitude – Angular distance above or below the horizon, measured along a vertical circle, to the celestial object. Angular measure – Measurement in terms of angles or degrees of arc. An entire circle is divided into 360 º, each degree in 60 ´ (minutes), and each minute into 60 ´´ (seconds). This scale is used to denote, among other things, the apparent size of celestial bodies, their separation on the celestial sphere, etc. One example is the diameter of the Moon’s disc, which measures approximately 0.5 º= 30 ´. Azimuth – The angle along the celestial horizon, measured eastward from the north point, to the intersection of the horizon with the vertical circle passing through an object. Big Bang Theory – States that the universe began as a tiny but powerful explosion of space-time roughly 13.7 billion years ago. Cardinal points – The four principal points of the compass: North, South, East, West. Celestial equator – Is the great circle on the celestial sphere defined by the projection of the plane of the Earth’s equator. It divides the celestial sphere into the northern and southern hemisphere. The celestial equator has a declination of 0 º. Celestial poles – Points above which the celestial sphere appears to rotate. Celestial sphere – An imaginary sphere of infinite radius, in the centre of which the observer is located, and against which all celestial bodies appear to be projected. Constellation – A Precisely defined part of the celestial sphere. In the older, narrower meaning of the term, it is a group of fixed stars forming a characteristic pattern.
    [Show full text]
  • The Celestial Sphere
    The Celestial Sphere Useful References: • Smart, “Text-Book on Spherical Astronomy” (or similar) • “Astronomical Almanac” and “Astronomical Almanac’s Explanatory Supplement” (always definitive) • Lang, “Astrophysical Formulae” (for quick reference) • Allen “Astrophysical Quantities” (for quick reference) • Karttunen, “Fundamental Astronomy” (e-book version accessible from Penn State at http://www.springerlink.com/content/j5658r/ Numbers to Keep in Mind • 4 π (180 / π)2 = 41,253 deg2 on the sky • ~ 23.5° = obliquity of the ecliptic • 17h 45m, -29° = coordinates of Galactic Center • 12h 51m, +27° = coordinates of North Galactic Pole • 18h, +66°33’ = coordinates of North Ecliptic Pole Spherical Astronomy Geocentrically speaking, the Earth sits inside a celestial sphere containing fixed stars. We are therefore driven towards equations based on spherical coordinates. Rules for Spherical Astronomy • The shortest distance between two points on a sphere is a great circle. • The length of a (great circle) arc is proportional to the angle created by the two radial vectors defining the points. • The great-circle arc length between two points on a sphere is given by cos a = (cos b cos c) + (sin b sin c cos A) where the small letters are angles, and the capital letters are the arcs. (This is the fundamental equation of spherical trigonometry.) • Two other spherical triangle relations which can be derived from the fundamental equation are sin A sinB = and sin a cos B = cos b sin c – sin b cos c cos A sina sinb € Proof of Fundamental Equation • O is
    [Show full text]
  • The Constellation a Newsletter for Answering Service Employees; Donated to the Industry by Teamsnug
    The Constellation A newsletter for Answering Service Employees; donated to the industry by TeamSNUG A Shining Star to Guide the Way… Today’s Luminary is Justin Wiggins from Main Line TeleCommunications Submitted By Julie Sparklin ig things come in small packages and Justin Wiggins is no exception! She started Delphinus with Main Line TeleCommunications (MLT) in 2004 as an agent. Her potential was B apparent early on and it was obvious that she enjoyed the variety of opportunities that an answering service provides. Constellation Justin moved through MLT’s Path to Success quickly progressing through 4 agent levels and 3 dispatch levels. Her A+ certification from the Chubb Institute made her a natural to learn to program Amtelco’s Infinity platform. Soon after mastering client updates, directories, and new accounts, she began training others and developing processes to teach Delphinus is a constellation programing skills. in the northern sky, close to the celestial equator. Its name Attention to detail, a steadfast commitment to quality, and a sincere desire to see her teammates as well as MLT succeed, made Justin became a Shift Leader. The position was is Latin for dolphin. new to MLT and she worked hard to help define the responsibilities and demonstrate Delphinus was one of the 48 leadership. Going from being a peer to leading your peers is not an easy transition but her constellations listed by the honest, fair, and consistent demeanor were key in gaining her teams trust and respect. 2nd century astronomer Justin moved to Murrells Inlet, South Carolina in 2006; and asked to become a remote Ptolemy, and it remains employee.
    [Show full text]
  • Appendix a Glossary
    BASICS OF RADIO ASTRONOMY Appendix A Glossary Absolute magnitude Apparent magnitude a star would have at a distance of 10 parsecs (32.6 LY). Absorption lines Dark lines superimposed on a continuous electromagnetic spectrum due to absorption of certain frequencies by the medium through which the radiation has passed. AM Amplitude modulation. Imposing a signal on transmitted energy by varying the intensity of the wave. Amplitude The maximum variation in strength of an electromagnetic wave in one wavelength. Ångstrom Unit of length equal to 10-10 m. Sometimes used to measure wavelengths of visible light. Now largely superseded by the nanometer (10-9 m). Aphelion The point in a body’s orbit (Earth’s, for example) around the sun where the orbiting body is farthest from the sun. Apogee The point in a body’s orbit (the moon’s, for example) around Earth where the orbiting body is farthest from Earth. Apparent magnitude Measure of the observed brightness received from a source. Astrometry Technique of precisely measuring any wobble in a star’s position that might be caused by planets orbiting the star and thus exerting a slight gravitational tug on it. Astronomical horizon The hypothetical interface between Earth and sky, as would be seen by the observer if the surrounding terrain were perfectly flat. Astronomical unit Mean Earth-to-sun distance, approximately 150,000,000 km. Atmospheric window Property of Earth’s atmosphere that allows only certain wave- lengths of electromagnetic energy to pass through, absorbing all other wavelengths. AU Abbreviation for astronomical unit. Azimuth In the horizon coordinate system, the horizontal angle from some arbitrary reference direction (north, usually) clockwise to the object circle.
    [Show full text]
  • 2. Descriptive Astronomy (“Astronomy Without a Telescope”)
    •How do we locate stars in the heavens? •What stars are visible from a given location? 2. Descriptive Astronomy •Where is the sun in the sky at any given time? (Astronomy Without a Telescope) •Where are you on the Earth? http://www.star.ucl.ac.uk/~idh/apod/ In 1930 the International Astronomical Union (IAU) ruled the heavens off into 88 legal, precise constellations. Every star, galaxy, etc., is a member of one of these constellations. Many stars are named according to their constellation and relative brightness (Bayer 1603). Sirius Centauri, -Canis see http://calgary.rasc.ca/constellation.htm#list Majoris, -Orionis An asterism is two stars that appear http://www.google.com/sky/ Betelgeuse To be close in the sky but actually arent http://www.seds.org/messier/ (1758 – 1782) Brief History E.g., ORION Some of the current constellations can be traced back to the inhabitants of the Euphrates valley, from whom they were handed down through the Greeks and Arabs. Few pictorial records of the ancient constellation figures have survived, but in the Almagest AD 150, Ptolemy catalogued the positions of 1,022 of the brightest stars both in terms of celestial latitude and longitude, and of their places in 48 constellations. The Ptolemaic constellations left a blank area centered not on the present south pole but on a point which, because of precession, would have been the south pole c. 2800 BC, a fact that is consistent with the belief that the constellation system had its origin about 5,000 Betelgeuse and Rigel are M42 = Orion nebula M43 = DeMairans nebula years ago.
    [Show full text]