Pluto & Other Minor Worlds Mc Neely 2010


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Pluto & Other Minor Worlds Mc Neely 2010

  1. 1. Pluto and Other Minor Worlds of the Solar System Comet Hale-Bopp, visible in 1997
  2. 2. Pluto Data Mean Distance from Sun 3,663,800,000 miles 39.4 AU Diameter at the Equator 1,457 miles Length of “Year” (revolution around the sun) 247.69 earth years Diameter if Earth = 1 0.18 Length of “Day” 6.39 earth days Mass if Earth = 1 0.002 Symbol Surface Gravity if Earth = 1 0.05
  3. 3. God of the Underworld <ul><li>Pluto : In Roman mythology, Pluto (Greek Hades) is the god of the underworld </li></ul><ul><li>The planet received this name because it’s so far from the sun that it is in perpetual darkness </li></ul>
  4. 4. No Respect <ul><li>Before 2006, Pluto was the smallest planet </li></ul><ul><li>Pluto is one of the largest Kuiper Belt objects, a belt of icy worlds that lie beyond the orbit of Neptune </li></ul><ul><li>In 2006, the world’s astronomers convened and decided that Pluto should be demoted to the status of “dwarf planet” </li></ul><ul><li>Other dwarf planets now include Ceres, the largest asteroid, and Eris (Xena), a world recently discovered beyond Pluto </li></ul>
  5. 5. New Horizons <ul><li>No Space Missions : Pluto has never been visited by a spacecraft </li></ul><ul><li>Our best images of Pluto have been obtained using the Hubble Space Telescope </li></ul><ul><li>The HST has been able to discern bright and dark patterns on Pluto’s surface </li></ul><ul><li>The New Horizons mission to Pluto was launched in January 2006 </li></ul><ul><li>The spacecraft will arrive at Pluto in 2015 </li></ul>
  6. 6. Pluto: HST
  7. 7. Pluto Surface Map (HST)
  8. 8. Pluto’s Odd Orbit <ul><li>Eccentric Orbit : Pluto’s orbit around the sun is highly eccentric and tilted in comparison to the rest of the solar system </li></ul><ul><li>At times Pluto is closer to the sun than Neptune </li></ul>
  9. 9. Pluto’s Orbit Pluto closer than Neptune
  10. 10. Similar to Triton <ul><li>Composition : Pluto is most likely composed of 75% rock and 25% water ice, similar to Neptune’s moon Triton </li></ul>
  11. 11. Charon <ul><li>Charon : Pluto’s large satellite </li></ul><ul><li>Discovered in 1978 by Jim Christy </li></ul><ul><li>Charon is the mythological figure who ferried the dead across the river Styx in Hades (the underworld) </li></ul><ul><li>Charon is unique in that it is the largest moon, when compared to its primary planet, in the solar system (the second largest is earth’s moon) </li></ul><ul><li>Pluto and Charon could be considered a double planet </li></ul>
  12. 12. Pluto and Charon (HST)
  13. 13. Nix and Hydra <ul><li>In 2005, the Hubble Space Telescope discovered two additional moons of Pluto </li></ul><ul><li>These moons have been named Nix and Hydra </li></ul>
  14. 14. Pluto System (HST)
  15. 15. Lore of Pluto <ul><li>Clyde Tombaugh : Pluto was discovered in 1930 by Clyde Tombaugh of the Lowell Observatory in Flagstaff, Arizona </li></ul><ul><li>Percival Lowell, famous for his theories of canals on Mars, had predicted the existence of a ninth planet and started the search carried out by Tombaugh </li></ul><ul><li>Tombaugh photographed portions of the sky and discovered Pluto as a faint dot in one of his photographs </li></ul><ul><li>Although it lied close to the position predicted by Lowell, the discovery of Pluto is considered to be a happy coincidence </li></ul>
  16. 16. Clyde Tombaugh
  17. 17. Bye Bye Pluto <ul><li>Status of Pluto decided at the 2006 meeting of the International Astronomical Union, (IAU) </li></ul><ul><li>After debate, Pluto was demoted to a new classification called “dwarf planet” </li></ul><ul><li>Two other dwarf planets are Ceres, the largest asteroid and Eris, a body discovered in 2005 that is larger than Pluto and lies further out </li></ul><ul><li>If dwarf planets are added to the traditional planets, then we now have 8 planets and 3 dwarf planets in the solar system </li></ul><ul><li>2008 : Dwarf planet Makemake added to list </li></ul><ul><li>2008 : Objects like Pluto beyond Neptune termed “plutoids” </li></ul>
  18. 18. IAU 2006 Planet Definition <ul><li>A Planet: </li></ul><ul><ul><li>Orbits the sun and is not a satellite </li></ul></ul><ul><ul><li>Is sphere-shaped </li></ul></ul><ul><ul><li>Has “cleared the neighborhood around its orbit of similar bodies” </li></ul></ul><ul><li>A Dwarf Planet </li></ul><ul><ul><li>All of the above, but has not cleared its orbit </li></ul></ul><ul><li>“ The eight &quot;planets&quot; are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune” </li></ul><ul><li>“ Pluto is a &quot;dwarf planet&quot; by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects“ </li></ul>
  19. 19. New Solar System <ul><li>Planets : </li></ul><ul><ul><li>Mercury </li></ul></ul><ul><ul><li>Venus </li></ul></ul><ul><ul><li>Earth </li></ul></ul><ul><ul><li>Mars </li></ul></ul><ul><ul><ul><li>Ceres </li></ul></ul></ul><ul><ul><li>Jupiter </li></ul></ul><ul><ul><li>Saturn </li></ul></ul><ul><ul><li>Uranus </li></ul></ul><ul><ul><li>Neptune </li></ul></ul><ul><ul><ul><li>Pluto </li></ul></ul></ul><ul><ul><ul><li>Eris </li></ul></ul></ul><ul><ul><ul><li>Makemake </li></ul></ul></ul>Eris
  20. 20. Should Pluto Considered a Planet? <ul><li>Yes </li></ul><ul><li>It has been called a planet since 1930 </li></ul><ul><li>It is round </li></ul><ul><li>It has satellites </li></ul><ul><li>It has an atmosphere </li></ul><ul><li>Other planets haven’t “cleared their orbits” </li></ul><ul><li>Even if it is just one of many, it should be kept as a planet out of tradition </li></ul><ul><li>New Horizons was sent because Pluto was the only “planet” not visited </li></ul><ul><li>Too difficult to explain </li></ul><ul><li>No </li></ul><ul><li>It is too small </li></ul><ul><li>It is just one of many thousands of similar worlds beyond Neptune (hasn’t “cleared its orbit” </li></ul><ul><li>Its orbit is odd (tilted, eccentric) </li></ul><ul><li>It doesn’t fit terrestrial or jovian categories </li></ul><ul><li>Eris is larger, shouldn’t it be a planet? </li></ul><ul><li>We can’t have thousands of planets beyond Neptune </li></ul><ul><li>Asteroids (between Mars and Jupiter) were at first named planets </li></ul>
  21. 21. Discovery of the Asteroids <ul><li>The first astreroid, Ceres, was discovered on New Year’s Day, 1801 </li></ul><ul><li>Father Giuseppi Piazzi discovered a faint, moving object in the sky </li></ul><ul><li>He realized that it lay between the orbits of Mars and Jupiter </li></ul><ul><li>Piazzi chose the name Ceres, the Roman goddess of grain and the protector of Sicily, Piazzi’s home </li></ul><ul><li>Ceres is the largest asteroid with a diameter of 623 miles </li></ul>
  22. 22. Ceres
  23. 23. Ceres: HST
  24. 24. Many Asteroids <ul><li>By 1807, three more asteroids were discovered </li></ul><ul><li>These are Juno, Pallas, and Vesta </li></ul><ul><li>Since then, many thousands of asteroids have been discovered </li></ul><ul><li>Most asteroids are found between the orbits of Mars and Jupiter </li></ul><ul><li>Some orbits share Jupiter’s orbit (Trojans) </li></ul>
  25. 25. Asteroid Belt
  26. 26. Asteroid Comparisons
  27. 27. Names of the Asteroids <ul><li>The discoverer of an asteroid is allowed to choose a name </li></ul><ul><li>The first names were from classical mythology </li></ul><ul><li>Eventually, as mythological names became scarce, various other names were used </li></ul><ul><li>The Beatles have asteroids, as well as Piazzi (Piazzia), and the Space Shuttle Challenger astronauts </li></ul>
  28. 28. First 25 Asteroids <ul><li>Number & Name </li></ul><ul><li>Ceres </li></ul><ul><li>Pallas </li></ul><ul><li>Juno </li></ul><ul><li>Vesta </li></ul><ul><li>Astraea </li></ul><ul><li>Hebe </li></ul><ul><li>Iris </li></ul><ul><li>Flora </li></ul><ul><li>Metis </li></ul><ul><li>Hygeia </li></ul><ul><li>Parthenope </li></ul><ul><li>Victoria </li></ul><ul><li>Egeria </li></ul>Diameter in Miles 623 378 143 334 73 121 130 94 94 280 93 79 139 <ul><li>Irene </li></ul><ul><li>Eunomia </li></ul><ul><li>Psyche </li></ul><ul><li>Thetis </li></ul><ul><li>Melpomene </li></ul><ul><li>Fortuna </li></ul><ul><li>Massalia </li></ul><ul><li>Lutetia </li></ul><ul><li>Calliope </li></ul><ul><li>Thalia </li></ul><ul><li>Themis </li></ul><ul><li>Phocaea </li></ul>98 169 155 68 93 134 81 72 110 69 145 45
  29. 29. Asteroids : No Accident <ul><li>The existence of a body or bodies between Mars and Jupiter had been predicted by Bode’s Law </li></ul><ul><li>When Uranus was discovered close to the position predicted by Bode’s Law, astronomers began searching for a missing object between Mars and Jupiter </li></ul><ul><li>There is no physical explanation for Bode’s Law, it is likely a coincidence </li></ul>
  30. 30. Bode’s Law <ul><li>“ Bode's&quot; Law was first described by Daniel Titius (1729-1796) who found that the distances of the planets follow a fixed formula </li></ul><ul><li>Bode's Law led astronomers to search for a &quot;missing&quot; planet between Mars and Jupiter. Piazzi found Ceres, the first asteroid, in 1801 </li></ul><ul><li>Why this works is a mystery. </li></ul><ul><li>Most likely an amazing coincidence </li></ul>
  31. 31. Bode’s Law <ul><li>Sequence : Start with 0, 3, and then double each number after </li></ul><ul><li>Add 4 to the sequence, than divide by 10 </li></ul><ul><li>The results are very close to the actual distances of most of the planets from the sun </li></ul><ul><li>Results are in astronomical units. One AU (astronomical unit) is the average earth-sun distance and equals 93,000,000 mi </li></ul>
  32. 32. Bode’s Law Table <ul><li>Neptune doesn’t fit </li></ul><ul><li>Eris average distance = 68AU </li></ul><ul><li>Eris’s Bode distance should be 77.2AU </li></ul>Add 4 Divide by 10 Actual Mercury 0 4 0.4 0.39 Venus 3 7 0.7 0.72 Earth 6 10 1.0 1 Mars 12 16 1.6 1.52 Ceres 24 28 2.8 2.8 Jupiter 48 52 5.2 5.2 Saturn 96 100 10 9.54 Uranus 192 196 19.6 19.19 Neptune 30.06 Pluto 384 388 38.8 39
  33. 33. Origin of the Asteroids <ul><li>The most widely accepted theory about asteroids is that they are planetisimals, ancient chunks of matter that never formed into a planet </li></ul><ul><li>Gravitational effects of Jupiter most likely prevented a planet from forming in this area </li></ul><ul><li>All known asteroids packed together would only equal 1/2000 the mass of the earth </li></ul>
  34. 34. To Neptune, and Beyond: The Kuiper Belt <ul><li>Kuiper Belt : A number of Pluto-like worlds beyond Neptune’s orbit </li></ul><ul><li>Icy, rocky worlds </li></ul><ul><li>About 1000 known, estimated 70,000 objects in belt </li></ul><ul><li>2008 : Term “plutoid” for dwarf planets beyond Neptune </li></ul>
  35. 35. Some Kuiper Belt Objects Name (date) Pluto (1930) Charon (1978)* Orcus (2004) Ixion (2001) Quaoar (2002) Eris (2003) Sedna (2004) *Pluto’s satellite Diameter (mi) 1400 750 940 514 800 1500 800-1100 Distance (AU) 39.4 39.4 40 40 43.5 68 78
  36. 36. Pluto & Beyond
  37. 38. Sedna <ul><li>Sedna is the object with the largest known orbit in our solar system </li></ul><ul><li>Sedna is the furthest object discovered in our solar system </li></ul><ul><li>Its orbit extends outside the Kuiper Belt, approaching the Oort cloud of comets </li></ul>
  38. 39. Sedna
  39. 40. Comets <ul><li>Comets are composed mainly of ice and rocky material, but are dark </li></ul><ul><li>Comets originate from areas far out in the solar system </li></ul><ul><li>Some comets move in toward the sun, and solar energy causes the outer crust of the comet to turn gaseous creating an immense, glowing cloud </li></ul>
  40. 41. Comet Structure <ul><li>Nucleus : Icy center </li></ul><ul><li>Coma : Glowing cloud surrounding the nucleus </li></ul><ul><li>Dust tail : Stream of solid particles emitted from the nucleus (source of meteor showers on earth), often forms a curved path </li></ul><ul><li>Ion tail : Stream of glowing gas emitted from the nucleus, always points away from the sun </li></ul>
  41. 42. Structure of a Comet Note : Coma, ion tail, dust tail, nucleus
  42. 43. Comet Lulin (2009) Note coma, dust tail
  43. 44. Hale-Bopp (1997) Dust tail-brown Ion tail-blue
  44. 45. Comet Holmes (2007) <ul><li>Comet Holmes developed a huge coma, larger than the sun </li></ul>
  45. 47. Giotto <ul><li>Giotto Mission: The first close-up images of a comet’s nucleus </li></ul><ul><li>Flew by Comet Halley in 1986 </li></ul><ul><li>Name refers to the artist Giotto who featured Halley’s Comet in a 1301 painting of the birth of Christ </li></ul>
  46. 48. Comet Nuclei <ul><li>Top : Comet Halley (Giotto) </li></ul><ul><li>Bottom : Comet Wild 2 (Stardust Mission) </li></ul>
  47. 49. Giotto’s Halley
  48. 50. Deep Impact <ul><li>NASA’s Deep Impact mission collided a large block of copper into the nucleus of comet Tempel 1 </li></ul><ul><li>Resulting debris was studied by the flyby craft </li></ul><ul><li>Deep Impact occurred in July 2005 </li></ul>Temple 1’s nucleus
  49. 51. Deep Impact: Wild 2 Nucleus
  50. 52. Comet Halley <ul><li>Edmond Halley predicted a comet’s return, and realized that they orbit the sun </li></ul><ul><li>Aristotle : Comets were phenomena of earth’s atmosphere </li></ul><ul><li>Tycho Brahe : Proved that comets are much farther from the earth </li></ul><ul><li>Halley : Comets in 1531, 1607, and 1682 were the same object with a period of 75-76 years </li></ul><ul><li>Halley predicted that the comet would return in 1758 </li></ul><ul><li>German farmer Georg Palitzsch was the first to spot the return of Halley’s comet </li></ul><ul><li>Halley’s Comet was last seen in 1986, and will return in 2061 (take your vitamins) </li></ul>
  51. 53. Great Comets <ul><li>Roughly ever ten years, great comets appear </li></ul><ul><li>Great comets are spectacularly bright and large </li></ul><ul><li>1965: Ikeya-Seki </li></ul><ul><li>1970: Bennett </li></ul><ul><li>1976: West </li></ul><ul><li>1996: Hyakutake </li></ul><ul><li>1997: Hale-Bopp </li></ul><ul><li>2007: McNaught </li></ul><ul><li>2007: Holmes </li></ul><ul><li>? </li></ul>
  52. 54. Ikeya-Seki (Oct, 1965)
  53. 55. Hyakutake (1996), 100 Degree Tail
  54. 56. Hale-Bopp (1997)
  55. 57. Meteors <ul><li>Also known as “shooting stars” </li></ul><ul><li>Meteors are a streak of light emitted by particles entering the earth’s atmosphere </li></ul><ul><li>Friction between the particle and gases in the atmosphere cause it to heat and glow </li></ul><ul><li>If the particle survives to land to the surface, it is termed a meteorite </li></ul>
  56. 58. Meteor Showers <ul><li>Meteor showers occur when earth passes through the debris left by a comet </li></ul><ul><li>Meteor showers are predictable events that occur on the same evenings each year </li></ul>
  57. 59. Major Meteor Showers <ul><li>Quadrantids—Jan 03 </li></ul><ul><li>Lyrids—Apr 21 </li></ul><ul><li>Eta Aquarids—May 04 </li></ul><ul><li>S. Delta Aquarids—July 29 </li></ul><ul><li>Perseids—Aug 11-12 </li></ul><ul><li>Orionids—Oct 20 </li></ul><ul><li>Leonids—Nov 17 </li></ul><ul><li>Geminids—Dec 13-14 </li></ul>
  58. 60. Meteorites <ul><li>Meteorites represent solid material that falls to the earth and survives its trip through the atmosphere </li></ul><ul><li>Meteorites come in three main categories: </li></ul><ul><ul><li>Stone </li></ul></ul><ul><ul><li>Iron </li></ul></ul><ul><ul><li>Stoney-Iron </li></ul></ul>
  59. 61. Types of Meteorites Stony Meteorites Iron Meteorites Widmanstatten Pattern Flakes of nickel-iron embedded in stone
  60. 62. Stony-Iron <ul><li>This pallasite meteorite contains crystals of olivine (peridot) embedded in nickel-iron </li></ul>
  61. 63. In 1969, the Allend meteorite created a dazzling blue display in the skies near Chihuahua, Mexico, before impact The dark blue color is due to carbon in the meteorite. This meteorite, a carbonaceous chondrite, is believed to contain unaltered material from the early Solar System (chondrules) SLICED OPEN
  62. 64. Stony: Carbonaceous Chondrites <ul><li>Rare stony meteorite </li></ul><ul><li>Contain carbon, and spherical pieces named chondrules </li></ul><ul><li>Chondrules are thought contain unaltered material from the early Solar System </li></ul>Chondrule 1969, Allende, Mexico
  63. 65. Tektites <ul><li>Another meteorite-related phenomena are tektites </li></ul><ul><li>Tektites are a form of glass created when meteorites hit the earth </li></ul><ul><li>Tektites are found in specific areas probably near the original impact </li></ul>
  64. 66. Libyan Desert Glass Robert Haag and Libyan Desert Glass
  65. 67. Australite Air Patterns <ul><li>This australite tektite shows apparent appears to have solidified in air </li></ul>
  66. 68. Meteor Crater <ul><li>Meteor Crater in northern Arizona is the best preserved meteor crater on earth </li></ul><ul><li>The crater was created about 10,000 years ago by the impact of an iron meteorite the size of a house </li></ul><ul><li>Many pieces of the original meteorite have been recovered </li></ul><ul><li>The crater is one mile in diameter and is a spectacular tourist attraction </li></ul>
  67. 69. Tunguska <ul><li>Trees flattened over an area 30 km in diameter by the Tunguska Impact in 1908 </li></ul><ul><li>The Tunguska event occurred in Siberia </li></ul><ul><li>The impactor was most likely a comet due to absence of any meteoritic material </li></ul>
  68. 70. Chicxulub <ul><li>The Chicxulub Crater, located in the ocean near Yucatan, is believed to be the impact crater dating from the extinction of the dinosaurs, 65 mya </li></ul><ul><li>Actual meteorite fragments from the Chicxulub event have been discovered in Pacific Ocean sediments </li></ul>