Chapter 13 Navigational Astronomy
Total Page:16
File Type:pdf, Size:1020Kb

Load more
Recommended publications
-
What Causes the Seasons? – How Does the Orientation of Earth's Axis Change with Time?
2.2 The Reason for Seasons • Our goals for learning: – What causes the seasons? – How does the orientation of Earth's axis change with time? © 2014 Pearson Education, Inc. Thought Question TRUE OR FALSE? Earth is closer to the Sun in summer and farther from the Sun in winter. © 2014 Pearson Education, Inc. Thought Question TRUE OR FALSE? Earth is closer to the Sun in summer and farther from the Sun in winter. Hint: When it is summer in America, it is winter in Australia. © 2014 Pearson Education, Inc. Thought Question TRUE OR FALSE! Earth is closer to the Sun in summer and farther from the Sun in winter. • Seasons are opposite in the N and S hemispheres, so distance cannot be the reason. • The real reason for seasons involves Earth's axis tilt. © 2014 Pearson Education, Inc. What causes the seasons? © 2014 Pearson Education, Inc. Axis tilt changes directness of sunlight during the year. © 2014 Pearson Education, Inc. Sun's altitude also changes with seasons Sun’s position at noon in summer: Higher altitude means more direct sunlight. Sun’s position at noon in winter: Lower altitude means less direct sunlight. Summary: The Real Reason for Seasons • Earth's axis points in the same direction (to Polaris) all year round, so its orientation relative to the Sun changes as Earth orbits the Sun. • Summer occurs in your hemisphere when sunlight hits it more directly; winter occurs when the sunlight is less direct. • AXIS TILT is the key to the seasons; without it, we would not have seasons on Earth. -
The Planisphere of the Heavens
The Planisphere of the Heavens by Steven E. Behrmann Book V Copyright© by Steven E. Behrmann All rights reserved 2010 First Draft (Sunnyside Edition) Dedication: This book is dedicated to my blessed little son, Jonathan William Edward, to whom I hope to teach the names of the stars. Table of Contents A Planisphere of the Heavens .......................................................... 12 The Signs of the Seasons ................................................................. 15 The Virgin (Virgo) ........................................................................... 24 Virgo ............................................................................................ 25 Coma ............................................................................................ 27 The Centaur .................................................................................. 29 Boötes ........................................................................................... 31 The Scales (Libra) ............................................................................ 34 Libra ............................................................................................. 35 The Cross (Crux) .......................................................................... 37 The Victim ................................................................................... 39 The Crown .................................................................................... 41 The Scorpion ................................................................................... -
Aquarius Aries Pisces Taurus
Zodiac Constellation Cards Aquarius Pisces January 21 – February 20 – February 19 March 20 Aries Taurus March 21 – April 21 – April 20 May 21 Zodiac Constellation Cards Gemini Cancer May 22 – June 22 – June 21 July 22 Leo Virgo July 23 – August 23 – August 22 September 23 Zodiac Constellation Cards Libra Scorpio September 24 – October 23 – October 22 November 22 Sagittarius Capricorn November 23 – December 23 – December 22 January 20 Zodiac Constellations There are 12 zodiac constellations that form a belt around the earth. This belt is considered special because it is where the sun, the moon, and the planets all move. The word zodiac means “circle of figures” or “circle of life”. As the earth revolves around the sun, different parts of the sky become visible. Each month, one of the 12 constellations show up above the horizon in the east and disappears below the horizon in the west. If you are born under a particular sign, the constellation it is named for can’t be seen at night. Instead, the sun is passing through it around that time of year making it a daytime constellation that you can’t see! Aquarius Aries Cancer Capricorn Gemini Leo January 21 – March 21 – June 22 – December 23 – May 22 – July 23 – February 19 April 20 July 22 January 20 June 21 August 22 Libra Pisces Sagittarius Scorpio Taurus Virgo September 24 – February 20 – November 23 – October 23 – April 21 – August 23 – October 22 March 20 December 22 November 22 May 21 September 23 1. Why is the belt that the constellations form around the earth special? 2. -
The Mathematics of the Chinese, Indian, Islamic and Gregorian Calendars
Heavenly Mathematics: The Mathematics of the Chinese, Indian, Islamic and Gregorian Calendars Helmer Aslaksen Department of Mathematics National University of Singapore [email protected] www.math.nus.edu.sg/aslaksen/ www.chinesecalendar.net 1 Public Holidays There are 11 public holidays in Singapore. Three of them are secular. 1. New Year’s Day 2. Labour Day 3. National Day The remaining eight cultural, racial or reli- gious holidays consist of two Chinese, two Muslim, two Indian and two Christian. 2 Cultural, Racial or Religious Holidays 1. Chinese New Year and day after 2. Good Friday 3. Vesak Day 4. Deepavali 5. Christmas Day 6. Hari Raya Puasa 7. Hari Raya Haji Listed in order, except for the Muslim hol- idays, which can occur anytime during the year. Christmas Day falls on a fixed date, but all the others move. 3 A Quick Course in Astronomy The Earth revolves counterclockwise around the Sun in an elliptical orbit. The Earth ro- tates counterclockwise around an axis that is tilted 23.5 degrees. March equinox June December solstice solstice September equinox E E N S N S W W June equi Dec June equi Dec sol sol sol sol Beijing Singapore In the northern hemisphere, the day will be longest at the June solstice and shortest at the December solstice. At the two equinoxes day and night will be equally long. The equi- noxes and solstices are called the seasonal markers. 4 The Year The tropical year (or solar year) is the time from one March equinox to the next. The mean value is 365.2422 days. -
The Basques of Lapurdi, Zuberoa, and Lower Navarre Their History and Their Traditions
Center for Basque Studies Basque Classics Series, No. 6 The Basques of Lapurdi, Zuberoa, and Lower Navarre Their History and Their Traditions by Philippe Veyrin Translated by Andrew Brown Center for Basque Studies University of Nevada, Reno Reno, Nevada This book was published with generous financial support obtained by the Association of Friends of the Center for Basque Studies from the Provincial Government of Bizkaia. Basque Classics Series, No. 6 Series Editors: William A. Douglass, Gregorio Monreal, and Pello Salaburu Center for Basque Studies University of Nevada, Reno Reno, Nevada 89557 http://basque.unr.edu Copyright © 2011 by the Center for Basque Studies All rights reserved. Printed in the United States of America Cover and series design © 2011 by Jose Luis Agote Cover illustration: Xiberoko maskaradak (Maskaradak of Zuberoa), drawing by Paul-Adolph Kaufman, 1906 Library of Congress Cataloging-in-Publication Data Veyrin, Philippe, 1900-1962. [Basques de Labourd, de Soule et de Basse Navarre. English] The Basques of Lapurdi, Zuberoa, and Lower Navarre : their history and their traditions / by Philippe Veyrin ; with an introduction by Sandra Ott ; translated by Andrew Brown. p. cm. Translation of: Les Basques, de Labourd, de Soule et de Basse Navarre Includes bibliographical references and index. Summary: “Classic book on the Basques of Iparralde (French Basque Country) originally published in 1942, treating Basque history and culture in the region”--Provided by publisher. ISBN 978-1-877802-99-7 (hardcover) 1. Pays Basque (France)--Description and travel. 2. Pays Basque (France)-- History. I. Title. DC611.B313V513 2011 944’.716--dc22 2011001810 Contents List of Illustrations..................................................... vii Note on Basque Orthography......................................... -
The Observer's Handbook for 1912
T he O bservers H andbook FOR 1912 PUBLISHED BY THE ROYAL ASTRONOMICAL SOCIETY OF CANADA E d i t e d b y C. A, CHANT FOURTH YEAR OF PUBLICATION TORONTO 198 C o l l e g e St r e e t Pr in t e d fo r t h e So c ie t y 1912 T he Observers Handbook for 1912 PUBLISHED BY THE ROYAL ASTRONOMICAL SOCIETY OF CANADA TORONTO 198 C o l l e g e St r e e t Pr in t e d fo r t h e S o c ie t y 1912 PREFACE Some changes have been made in the Handbook this year which, it is believed, will commend themselves to observers. In previous issues the times of sunrise and sunset have been given for a small number of selected places in the standard time of each place. On account of the arbitrary correction which must be made to the mean time of any place in order to get its standard time, the tables given for a particualar place are of little use any where else, In order to remedy this the times of sunrise and sunset have been calculated for places on five different latitudes covering the populous part of Canada, (pages 10 to 21), while the way to use these tables at a large number of towns and cities is explained on pages 8 and 9. The other chief change is in the addition of fuller star maps near the end. These are on a large enough scale to locate a star or planet or comet when its right ascension and declination are given. -
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. -
Chapter 7 Mapping The
BASICS OF RADIO ASTRONOMY Chapter 7 Mapping the Sky Objectives: When you have completed this chapter, you will be able to describe the terrestrial coordinate system; define and describe the relationship among the terms com- monly used in the “horizon” coordinate system, the “equatorial” coordinate system, the “ecliptic” coordinate system, and the “galactic” coordinate system; and describe the difference between an azimuth-elevation antenna and hour angle-declination antenna. In order to explore the universe, coordinates must be developed to consistently identify the locations of the observer and of the objects being observed in the sky. Because space is observed from Earth, Earth’s coordinate system must be established before space can be mapped. Earth rotates on its axis daily and revolves around the sun annually. These two facts have greatly complicated the history of observing space. However, once known, accu- rate maps of Earth could be made using stars as reference points, since most of the stars’ angular movements in relationship to each other are not readily noticeable during a human lifetime. Although the stars do move with respect to each other, this movement is observable for only a few close stars, using instruments and techniques of great precision and sensitivity. Earth’s Coordinate System A great circle is an imaginary circle on the surface of a sphere whose center is at the center of the sphere. The equator is a great circle. Great circles that pass through both the north and south poles are called meridians, or lines of longitude. For any point on the surface of Earth a meridian can be defined. -
Trajectory Coordinate System Information We Have Calculated the New Horizons Trajectory and Full State Vector Information in 11 Different Coordinate Systems
Trajectory Coordinate System Information We have calculated the New Horizons trajectory and full state vector information in 11 different coordinate systems. Below we describe the coordinate systems, and in the next section we describe the trajectory file format. Heliographic Inertial (HGI) This system is Sun centered with the X-axis along the intersection line of the ecliptic (zero longitude occurs at the +X-axis) and solar equatorial planes. The Z-axis is perpendicular to the solar equator, and the Y-axis completes the right-handed system. This coordinate system is also referred to as the Heliocentric Inertial (HCI) system. Heliocentric Aries Ecliptic Date (HAE-DATE) This coordinate system is heliocentric system with the Z-axis normal to the ecliptic plane and the X-axis pointes toward the first point of Aries on the Vernal Equinox, and the Y- axis completes the right-handed system. This coordinate system is also referred to as the Solar Ecliptic (SE) coordinate system. The word “Date” refers to the time at which one defines the Vernal Equinox. In this case the date observation is used. Heliocentric Aries Ecliptic J2000 (HAE-J2000) This coordinate system is heliocentric system with the Z-axis normal to the ecliptic plane and the X-axis pointes toward the first point of Aries on the Vernal Equinox, and the Y- axis completes the right-handed system. This coordinate system is also referred to as the Solar Ecliptic (SE) coordinate system. The label “J2000” refers to the time at which one defines the Vernal Equinox. In this case it is defined at the J2000 date, which is January 1, 2000 at noon. -
From Our Perspective... the Ecliptic
2/9/09 Why don’t we see the same Mastering Astronomy Assignment 3 constellations throughout the year? • Due Feb 17, 11 am • Read Sections 2.1, 2.2 and S1.2 The Earth also revolves around the Sun, From our perspective... which changes our view of the stars March September Earth circles the Sun in 365.25 days and, The Ecliptic consequently, the Sun appears to go once around the ecliptic in the same period. If we could see • As the Earth orbits background stars in the daytime, our Sun would the Sun, the Sun appears to move a) appear to move against them at a rate of 360° per eastward among the day. stars following a path b) appear to move against them at a rate of about called the ecliptic 15° per day. • The ecliptic is a c) appear to move against them at a rate of about 1° projection of Earth’s per day. orbit onto the The tilt of the Earth's axis d) remain stationary against these stars. celestial sphere causes the ecliptic to be tilted to the celestial equator 1 2/9/09 The sky varies as Earth orbits the Sun • As the Earth orbits the Sun, the Sun appears to move along the Zodiac ecliptic. • At midnight, the stars on our meridian are opposite the Sun in The 13 Zodiacal constellations that our Sun the sky. covers-up (blocks) in the course of one year (used to be only 12) • Aquarius • Leo • Pisces • Libra • Aries • Virgo • Scorpius • Taurus • Ophiuchus • Gemini • Sagittarius • Cancer • Capricornus The Zodiacal Constellations that our Sun blocks in the course of one year (only 12 are shown here) North Star Aquarius Pisces Capricornus Aries 1 day Sagittarius Taurus Scorpius 365 days Libra Gemini Virgo Cancer Leo North Star Aquarius Pisces Capricornus In-class Activities: Seasonal Stars Aries 1 day Sagittarius • Work with a partner! Taurus Scorpius • Read the instructions and questions carefully. -
3.- the Geographic Position of a Celestial Body
Chapter 3 Copyright © 1997-2004 Henning Umland All Rights Reserved Geographic Position and Time Geographic terms In celestial navigation, the earth is regarded as a sphere. Although this is an approximation, the geometry of the sphere is applied successfully, and the errors caused by the flattening of the earth are usually negligible (chapter 9). A circle on the surface of the earth whose plane passes through the center of the earth is called a great circle . Thus, a great circle has the greatest possible diameter of all circles on the surface of the earth. Any circle on the surface of the earth whose plane does not pass through the earth's center is called a small circle . The equator is the only great circle whose plane is perpendicular to the polar axis , the axis of rotation. Further, the equator is the only parallel of latitude being a great circle. Any other parallel of latitude is a small circle whose plane is parallel to the plane of the equator. A meridian is a great circle going through the geographic poles , the points where the polar axis intersects the earth's surface. The upper branch of a meridian is the half from pole to pole passing through a given point, e. g., the observer's position. The lower branch is the opposite half. The Greenwich meridian , the meridian passing through the center of the transit instrument at the Royal Greenwich Observatory , was adopted as the prime meridian at the International Meridian Conference in 1884. Its upper branch is the reference for measuring longitudes (0°...+180° east and 0°...–180° west), its lower branch (180°) is the basis for the International Dateline (Fig. -
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.