Celestial bodies a history of planetary discovery

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CELESTIAL BODIES A History of Planetary Discovery

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  • CELESTIAL BODIESA History of Planetary Discovery

  • PART I: CLASSICAL PLANETSO Venus, beauty of the skies,

    To whom a thousand temples rise, Gaily false in gentle smiles, Full of love-perplexing wiles;

    O goddess, from my heart remove The wasting cares and pains of love.

    - Sappho, Greece, ~600 BCE

  • asteres planetai

    Ancient Greek: wandering stars

  • Apparent MagnitudeVisible to the typical human eye

    Apparent magnitude

    Brightness relative to Vega

    Number of stars brighter than apparent magnitude

    Yes -1.0 250% 1

    0 100% 4

    1 40% 15

    2 16% 48

    3 6.30% 171

    4 2.50% 513

    5 1.00% 1602

    6 0.40% 4800

    6.5 0.25% 9096

    No 7 0.16% 14000

    8 0.06% 42000

    9 0.03% 121000

    10 0.01% 340000

  • Mars AM: -3.0 to +1.6 Orbital period: 686 days

    Saturn AM: -0.24 to +1.47 Orbital period: 29.5 years

    Jupiter AM: -2.94 to -1.6 Orbital period: 11.9 years

    Mercury AM: -2.6 to +5.7 Orbital period: 88 days

    Venus AM: -4.9 to -3.8 Orbital period: 224 days

  • Venus The Morningstar and Eveningstar Brightest objet in the sky, after the moon Overtakes Earth every 584 days, moving

    from being visible in the morning to the evening

  • Mayan astronomy

    Mayans Chack ek - the Great Star Thought to influence life on Earth;

    wars and other important events timed based on its position

    Mayans Dresden Codex included an almanac showing full cycle in five sets of 584 days each

  • Yolngu (Northern Australia) Barnumbirr In the early hours before dawn, Venus draws a rope of light attached

    to Earth Along this Morning Star Pole, the people can communicate with their


  • Babylonian Astronomy

  • Babylonian Venus Tablets Ammisaduqua, 7th century BCE Babylonians were first recorded civilization to recognize

    astronomical phenomena as periodic and apply math Venus tablets recorded rising and setting of Venus over 21

    years Babylonian astrologers laid foundation for western


  • Ancient Greece Developed mathematical models for

    predicting the paths of planets Named planets after gods; Roman

    interpretations give todays names 2nd century Almagest provided

    geocentric model that was astronomical standard for 1,200 years

  • PART II: MODERN PLANETSLe Verrierwithout leaving his study, without even looking at the skyhad found the unknown planet

    [Neptune] solely by mathematical calculation, and, as it were, touched it with the tip of his pen!

    Franois Arago, France, 1846

  • Nicolaus Copernicus De revolutionibus orbium coelestium, 1543 First to propose heliocentric (sun) model

    for universe

  • Galileo Galilei Father of modern astronomy Made significant advances to telescope Recorded phases of Venus Discovered 4 moons of Jupiter Controversially advocated for

    heliocentricsm; jailed by the inquisition

  • Johannes Kepler Laws of planetary motion, 1621 Stated that the orbit of a planet is an

    ellipse with the Sun at one of the two foci.

  • Isaac Newton Philosophi Naturalis Principia Mathematica, 1687 Laid foundation for classical mechanics Outlined law of universal gravitation:

    Any two bodies in the universe attract each other with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them

  • Sir William Herschel Observed Uranus on March 13, 1781 Noted its movement; initially reported it

    to be a comet Within the year, circular orbit had been

    identified and it was noted to be a planet

  • Uranus Apparent Magnitude: 5.9 to 5.32 Orbital period: 84.0 years Aphelion: 20.09 AU Perihelion: 18.28 AU Equatorial radius: 4.01 earths Moons: Numerous Ice giant, with more ices (water, ammonia,

    methane in its atmosphere than S/J) Coldest planetary atmosphere in the

    solar system (minimum temperature of 49 K)

  • Aberrations in Uranus Orbit

  • Discovery of Neptune September 23-24, 1846 Urbain Le Verriers work predicted

    position of new planet Johann Galle found new planet within 1

    degree of predicted position Dramatic confirmation of Newtonian

    gravitational theory

  • Neptune Apparent Magnitude: 8.02 to 7.78 Orbital period: 165 years Aphelion: 30.33 Perihelion: 29.8 Equatorial radius: 3.9 Earths Moons: 14 Densest of gas giants (also known as an

    ice giant)

  • But what about pluto?

  • There goes the neighborhood

    Eris was discovered in January 2005 and found to be 27% more massive than Pluto.

  • Estimated number of dwarf planets in our solar system:


  • PART III: EXOPLANETS[I]f our solar system is not unusual, then there are so many planets in the universe that, for

    example, they outnumber the sum of all sounds and words ever uttered by every human who has ever lived. To declare that Earth must be the only

    planet with life in the universe would be inexcusably bigheaded of us.

    Neil deGrasse Tyson

  • Radial Velocity Detecting minor orbit of star caused by orbiting planet

    Transit Detecting decrease in light when planet transits in front of star

    Direct Imaging Only possible for large planets that are far away from dim stars

    Gravitational Lensing Detecting minor changes in light from source star from lensing planet

    Timing variations Orbiting planets cause changes in periodic phenomena

  • 2M1207

    TrEs-3b Orbits the star GSC 03089-00929 Has an orbital period of just 31 hours;

    undergoing orbital decay Has nearly twice the mass of Jupiter Found with transiting survey; mass

    confirmed with radial velocity measurements of host star

    TrEs-3b (artists interpretation)Jupiter (really)

  • Kepler Mission Launched March 7, 2009 Spacecraft equipped with photometer to find transiting planets

    Studies 145,000 stars in a fixed position in the Milky Way

  • Kepler-20f Closest radius to Earth of any

    exoplanet discovered Surface temperature is 705K

    (a little too hot for liquid water)

    (still just an artists interpretation)

  • Estimated number of solar systems in our galaxy:

    >100 Billion