The Armagh Observatory Human Orrey
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The Armagh Observatory Human Orrey

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"The Armagh Observatory Human Orrey"...

"The Armagh Observatory Human Orrey"
Mark Bailey

Presentation of Armagh Observatory outreach initiatives and the Human Orrey. Presented at 2nd UNAWE International Workshop.

(Date: October 2006)

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The Armagh Observatory Human Orrey The Armagh Observatory Human Orrey Document Transcript

  • Mark E. Bailey, David J. Asher, and The Armagh Observatory Human OrreryApostolos A. Christou The Armagh Observatory Human Orrery Mark E. Bailey, David J. Asher and Apostolos A. Christou meb@arm.ac.uk http://star.arm.ac.uk The Human Orrery An orrery is a dynamic solar system model • designed to illustrate the heliocentric world-view In a Human Orrery people become the planets • the whole of solar system astronomy can be investigated in a fun way “on the ground” The simplest Human Orreries are not to scale • e.g. planets on circular orbits; no accurate link to the planets’ true positions in space versus time ! => only a limited range of activities possible They become more interesting when laid out with greater care • e.g. the Dynic Astropark Human Orrery (Japan) The Human Orrery is as versatile as a sundial • the Armagh model has an accurate scale of 1:150 billion, and a fixed time-step of 16 days ! it shows the 6 classical planets,1 asteroid and 2 comets at any time Dynic Astropark Human ! it includes the 13 ecliptic constellations, as well as Orrery (c.1997) directions to more distant objects in the Universe 2nd UNAWE Workshop Leiden, 2006 Oct. 12RAS, London, 13 January 2006 1
  • Mark E. Bailey, David J. Asher, and The Armagh Observatory Human OrreryApostolos A. Christou Why “Orrery”? Invented around 1704 by George Graham (c.1674–1751) • he gave a copy (or its design) to John Rowley (1674–1728), the celebrated London instrument maker Rowley made a copy for Prince Eugène of Savoy • he then made another for his patron, Charles Boyle, the fourth Earl of Orrery Charles Boyle (1674–1731) • author, soldier and statesman • grandson of Roger Boyle (1621–1679), the first Earl of Orrery ! a son of Richard Boyle, the first (or Great) Earl of Cork (1566–1643) ! in his day, “one of the richest men on the planet” The name “orrery” for such a model was popularized by the Irish essayist Sir Richard Images © Science Museum Steele (1672–1729) and National Portrait Gallery 2nd UNAWE Workshop Leiden, 2006 Oct. 12 Rowley’s Orrery, in Science Museum 2nd UNAWE Workshop Leiden, 2006 Oct. 12RAS, London, 13 January 2006 2
  • Mark E. Bailey, David J. Asher, and The Armagh Observatory Human OrreryApostolos A. Christou John, Fifth Earl of Cork and Orrery (b.1707) Orrery, invented by Graham 1700. Improved by Rowley and presented by him to John, Fifth Earl of Orrery, after whom it was named at the suggestion of Richard Steele 2nd UNAWE Workshop Leiden, 2006 Oct. 12 Ground-Based Astronomy for All… Each orbital tile shows various astronomical data • the name; tile number; date; distance from Sun; ecliptic longitude; and true anomaly With a simple “key” shown on the central Sun-tile 2nd UNAWE Workshop Leiden, 2006 Oct. 12RAS, London, 13 January 2006 3
  • Mark E. Bailey, David J. Asher, and The Armagh Observatory Human OrreryApostolos A. Christou Principal Features The Armagh Human Orrery shows: • the elliptical orbits and changing positions of various solar system objects versus time ! provides an accurate “map” of the solar system, giving users a better “feel” for the Earth’s position in space ! enables all of Kepler’s laws to be discovered by direct measurement; the times of meteor showers from the two comets; and much more… • the relative orbital periods and positions of the different orbital objects • the thirteen ecliptic constellations through which the Sun passes in a year ! which ones are visible at different times of year ! and that the First Point of Aries is in Pisces! • the directions to more distant objects in the Universe ! facilitating discussion of the variety of different “animals” in the astronomical “zoo” Most important, it is fun to use! 2nd UNAWE Workshop Leiden, 2006 Oct. 12 Location in the Observatory Grounds 2nd UNAWE Workshop Leiden, 2006 Oct. 12RAS, London, 13 January 2006 4
  • Mark E. Bailey, David J. Asher, and The Armagh Observatory Human OrreryApostolos A. Christou Overview of Human Orrery 2nd UNAWE Workshop Leiden, 2006 Oct. 12 Some Orrery Activities “Walking the Orrery” and “Running the Orrery” (and how fast can you go…) • investigating Kepler’s third law Finding the planets “tonight” (or at any other date) • and discovering which can be seen after dark at night, or as morning or evening stars • investigating conjunctions, oppositions and alignments; and the visibility of distant stars Measuring angles and distances between objects • working out distances and speeds in space • investigating Kepler’s laws by direct measurement • investigating the mathematics of orbital motion and of ellipses (areas, circumferences etc.) • using a “map” with a scale of 1:150,000,000,000 Learning new mathematical and calendrical concepts • counting (more than 200 tiles!) • modular arithmetic (e.g. 14 tiles for Venus etc.) • ratios of planetary orbital periods (e.g. 8/13 V/E) • “leap steps”, “leap stops” and Leap Years 2nd UNAWE Workshop Leiden, 2006 Oct. 12RAS, London, 13 January 2006 5
  • Mark E. Bailey, David J. Asher, and The Armagh Observatory Human OrreryApostolos A. Christou Other Activities and Games History, design, teamwork, dance and play! 2nd UNAWE Workshop Leiden, 2006 Oct. 12 Summary and Conclusions The Armagh Human Orrery (http://star.arm.ac.uk/orrery) • a dynamic solar system model where people become the moving objects • the first outdoor exhibit to show with precision the orbits and positions of the main solar system bodies • engages people in maths, space science and astronomy ! introduces key concepts of astronomy, as well as pointers to more distant objects in the Universe, in a fun and entertaining way • brings “heaven down to Earth”; provides an improved understanding of Earth’s changing position in space ! encourages people to observe the sky, and to compare what they see from “Earth” — on the ground — with what they see from Earth — in the sky • facilitates a wide range of interdisciplinary activities ! e.g. ranging from history, astrology and the development of astronomy, to dance, physical exercise and design • easy to make, easy to use, and as versatile as a sundial 2nd UNAWE Workshop Leiden, 2006 Oct. 12RAS, London, 13 January 2006 6
  • Mark E. Bailey, David J. Asher, and The Armagh Observatory Human OrreryApostolos A. Christou Acknowledgements We thank especially Miruna Popescu and Brendan Owens for their help with images and other material Astronomy at Armagh Observatory is funded by the Northern Ireland Department of Culture, Arts and Leisure meb@arm.ac.uk http://star.arm.ac.uk Orbital Periods, Leap Steps and Leap Stops Planet Orbital Orbital Number Leap Step Number Number of Period Period of Tiles or Leap of Orbits Earth (days) (years) per Orbit Stop? for Leap Years for Step/Stop Step/Stop Mercury 87.969 0.2408 5.5 STEP 520 125 Venus 224.701 0.6152 14 STOP 23 14 Earth 365.256 1.0000 23 STEP 6 6 Mars 686.980 1.8808 43 STEP 16 30 Ceres* 1681.592 4.6039 21* STOP 50 230 Jupiter** 4332.589 11.862 27** STOP 13 154 Saturn** 10759.23 29.457 67** STOP 4 118 *Tiles every 80 days **Tiles every 160 days 2nd UNAWE Workshop Leiden, 2006 Oct. 12RAS, London, 13 January 2006 7
  • Mark E. Bailey, David J. Asher, and The Armagh Observatory Human OrreryApostolos A. Christou Find the Planets The Human Orrery can show where the planets are at any time. To do this use the Earth as a key. Earth in Space STEP 1: Find the nearest Earth tile for the chosen time of year. For Choose an object and a date (for example, Mars on 2010 August 13). Use example, Earth is at tile number “14” on August 13 of any year. Keep this the method described above to locate the Earth and the object at this time. Earth tile number (“14”) in your head. Now stand on the Earth’s tile and look towards the central Sun tile. If the planet is to the left of the Sun tile, then it will be visible from Earth as STEP 2: Find the Start Tile for the chosen planet and year using the table. an “evening star”. If it is to the right, it will be visible as a “morning star”. If it This gives the planet’s position on January 1 for each year. For example, on 2010 January 1 Jupiter is at tile “114” and Mercury is at tile “4”. lies beyond the Sun tile, or (in the case of Mercury and Venus) possibly between the Earth and the Sun, then it will be a daytime object and not visible at night. If the planet is behind you (i.e. opposite the Sun in space), then it will be visible all night. Planets can be seen when the sky is clear, so you can check your result on the next clear night. You may find cases when planets appear to line up in the same direction as seen from Earth or another vantage point in space. This is a planetary grouping or alignment. For example, Mercury, Venus and Saturn were closely aligned at tile numbers “0”, “11” and “11”, as seen from Earth (tile “11”), on 2005 June 26. Looking farther afield, beyond the solar system, the Human Orrery shows the thirteen (not twelve) zodiacal constellations traversed by the Sun in the course of a year, the constellation boundaries, and the directions to a variety of more distant objects in the Universe. You can use the Human Orrery to discover when these constellations and other objects can be seen at night. Positions of orbital objects on January 1 for each year. STEP 3: Go to the Start Tile and move forward the same number of steps as the Earth tile number from STEP 1. In the case of Jupiter, stepping forward 14 tile-steps brings you to tile “128”. Note that the tiles for Jupiter and Saturn are marked every ten steps so that you must find the next closest tile (“130”) or make a rough estimate of tile position. For the two comets and the asteroid, tiles are marked every 5 steps. Positions of the six classical planets for a range of interesting dates. For Mercury, be careful to follow the order of tiles, which are interleaved. Also, when tile “0” is reached (for Mercury or any other planet) you must continue around the orbit again. For Mercury, in this example, you should 2nd UNAWE Workshop reach tile “7” for 2010 August 13 after moving forward 14 steps. Leiden, 2006 Oct. 12 The Human Orrery What is an Orrery? The small yellow dot at the The orbital tiles show An orrery is a dynamic model of the solar system. The Human Orrery is an orrery in centre of the Sun tile data such as tile represents the size of the number, date, and which people play the role of the moving planets. The first orrery, a mechanical device, was invented around 1704 by the English clockmaker George Graham (c.1674–1751). Sun (about 1.4 million km) the values of L, r, and on the scale of the Human f. This showed the Earth and Moon orbiting the Sun, but later models showed all the known planets. Orrery. Walking the Orrery First, choose a planet and find its Start Tile, for example the tile labelled “0”, which is the planet’s position on 2005 January 1. Now move from tile 0 to 1 to 2 and so on. Each step corresponds to 16 days of time. Repeat this for other planets to see how their speed changes with distance from the Sun. If you are part of a group, each person can be a di!erent planet and you can walk the orrery in lock-step on the call of a group leader. The name “Orrery” comes from the patronage of Charles Boyle (1674–1731), the fourth Earl of Orrery, Co. Cork, who commissioned a copy of the first orrery from the London instrument maker, John Rowley. The Armagh Human Orrery is the first outdoor exhibit to show with precision the elliptical orbits and changing positions of the planets and other solar system objects with time. With this exhibit, you can imagine you are a planet, asteroid or comet, and follow its path around the Sun. You can investigate the laws of planetary motion, work out the positions of the planets at any time, their distances from one another and when they are visible from Earth. The model also shows the directions from Earth of more distant objects in the Universe. Note that the asteroid Ceres and the two comets (Encke and Halley) are shown every five time-steps (80 days), and Jupiter and Saturn every ten time-steps (160 days). When you come to the last tile of a given orbit, make sure you move on to the next tile, Sun Tile labelled “0”, and start counting 0 to 1 to 2 again. Also, observe that Mercury’s eleven tiles represent two revolutions of that planet around the Sun. At the centre of the Human Orrery lies the Sun tile. This presents a key to the information on the orbital tiles. The letter r denotes the distance from the Sun in “Walking the Orrery” shows that planets nearer the Sun move faster. You can also see when planets come close to one another or line up as seen from Earth or another point astronomical units (AU), where 1 AU is approximately 150 million kilometres. The scale of the Human Orrery is 1:150 billion, so 1 metre on the ground corresponds to 1 AU in on the orrery. In fact, the Human Orrery provides an accurate “map” of the solar system, enabling all the laws of planetary motion to be discovered by direct measurement on the space. ground. The true anomaly f is the angle measured around the orbit from the object’s point of closest approach (perihelion) to the Sun. L denotes the ecliptic longitude of the object, measured anti-clockwise from the direction of the First Point of Aries, which is shown on the Sun tile and also on the plaque fixed to the Robinson Dome. As viewed from Armagh (in the northern hemisphere) all the planets revolve around the Sun anti-clockwise, in the direction of increasing L. On the Human Orrery only Comet Halley revolves in a clockwise, “retrograde” direction. 2nd UNAWE Workshop Leiden, 2006 Oct. 12RAS, London, 13 January 2006 8
  • Mark E. Bailey, David J. Asher, and The Armagh Observatory Human OrreryApostolos A. Christou Observatory Grounds and Astropark 2nd UNAWE Workshop Leiden, 2006 Oct. 12 Education and Public Outreach Exhibitions, Tours, Public Lectures, Open Days • library, archives and rare books • public lectures, school and undergraduate work experience • developing Observatory Grounds, Astropark, and Human Orrery 2nd UNAWE Workshop Leiden, 2006 Oct. 12RAS, London, 13 January 2006 9
  • Mark E. Bailey, David J. Asher, and The Armagh Observatory Human OrreryApostolos A. Christou Some Historic Instruments 2nd UNAWE Workshop Leiden, 2006 Oct. 12 Why Astronomy?! Underpinned by three main strands of interest: • the broadly “religious” or cosmological strand ! the quest to understand our “Origins”, Man’s place in the Universe • the broadly “practical” strand, i.e. commercial, military, or economic “spin-off” from astronomy, including education ! e.g. the Calendar; Navigation; Celestial Mechanics; Earth Observation; Image Processing; the “Inspiration” of Astronomy • the broadly “scientific” strand of curiosity driven research into Mathematics, Planetary Science and Astrophysics ! the project, no less, to understand the nature, contents and interactions of all the objects in the entire Universe… We live at an exceptional time: a “Golden Age” in which activity in all these areas is at an all-time high • provides astronomy with a rare conjunction of opportunity • contributes to the unprecedented advances in observation and theory (the former almost always leading the latter) 2nd UNAWE Workshop Leiden, 2006 Oct. 12RAS, London, 13 January 2006 10
  • Mark E. Bailey, David J. Asher, and The Armagh Observatory Human OrreryApostolos A. Christou Location of the Armagh Observatory 2nd UNAWE Workshop Leiden, 2006 Oct. 12 Montage Overview of Human Orrery 2nd UNAWE Workshop Leiden, 2006 Oct. 12RAS, London, 13 January 2006 11
  • Mark E. Bailey, David J. Asher, and The Armagh Observatory Human OrreryApostolos A. Christou Overview of Human Orrery 2nd UNAWE Workshop Leiden, 2006 Oct. 12RAS, London, 13 January 2006 12