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The contents

The contents. The Solar System is a dynamic collection of many hundreds of thousands of objects: The Sun, planets, dwarf planets, moons, asteroids, comets, Kuiper-belt objects, meteoroids, dust grains…. Also : magnetic fields, radiation (light), cosmic rays….

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The contents

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  1. The contents The Solar System is a dynamic collection of many hundreds of thousands of objects: The Sun, planets, dwarf planets, moons, asteroids, comets, Kuiper-belt objects, meteoroids, dust grains…. Also: magnetic fields, radiation (light), cosmic rays… The planets are the largest objects (next to the Sun) in the Solar System – but the definition for planetary status is not simple (or even agreed upon) Eight classical planets are recognized: Mercury  Neptune and five dwarf planets: Ceres, Pluto, Eris, Makemake & Haumea

  2. Inner solar system planets Outer solar system planets Dwarf planets

  3. 200,000 AU Oort Cloud KB Kuiper Belt 20,000 AU Sun Pluto 40 AU The scale of the Solar System Oort Cloud – named after Jan Oort (1950) – vast reservoir of comets surrounding Sun (spherical halo of objects) Comets can enter the inner solar system at any angle Kuiper Belt – named after Gerald Kuiper (1951) – disk like distribution of large ice / rock objects

  4. Light travel time across the Oort Cloud  OOTETK Velocity = speed of light Distance ~ 200,000 AU Meters in 1 AU Time = distance / velocity = 200,000 x 1.496 x 1011 / 3 x 108 = 9.97 x 107 seconds = 3.16 years The solar system is BIG!!.... Way big

  5. By any other name…. Conditions for planetary status: IAU (August 2006) definition: Object must orbit the Sun Large enough to be spherical through its own gravity – (this is a size / mass constraint) Must have ‘cleared’ its region of the solar system of other (smaller) objects International Astronomical Union

  6. Dwarf Planets An object that satisfies conditions 1 and 2 for planets but not condition 3 Dwarf planets presently recognized: Ceres – formerly the largest asteroid (historically a former planet – discovered 1801) Pluto – formerly a planet (discovered 1930) Eris – formerly a Kuiper belt object discovered 2003 Makemake - discovered 2005 Haumea – discovered 2004

  7. Moon Planets Haumea Makemake Dwarf planets Pluto Ceres Eris

  8. The Solar System 134340 Pluto 136199 Eris Makemake Haumea Ceres (dwarf planet) Physical properties

  9. The Main Components Are: Sun The nearest star to us. ~ 8% of all stars are Sun-like stars Accounts for 99.9% of the mass of the solar system Planets Terrestrial planets: Mercury  Mars Small, rocky (metal core) worlds with orbits less than 2 AU from the Sun Jovian planets: Jupiter  Neptune Large, mostly gas-giant planets with orbits greater than 5 AU from the Sun See ASTRO: section 12.2 – pages 243 – 244 and figure 1.7 on page 6

  10. Outer Solar System Inner Solar System Terrestrial planets: closely packed orbits Jovian planets: widely spaced orbits

  11. Dwarf Planets • Ceres aside – have orbits beyond Neptune • Pluto is essentially the first of the Dwarf Planets • Have orbits beyond 35 AU • Made predominantly of rock and ice • Sizes smaller than Earth’s Moon (< 3000 km) • It is possible that large (Earth-sized) DPs exist – but none have so far been detected • Move in the Kuiper Belt region and can/do undergo collisions with KBOs • Presently 5 Dwarf Planets ‘officially’ recognized, dozens, even many hundreds more awaiting discovery Plutoids

  12. The Smaller Bodies Minor planets (between Mars and Jupiter): rock / metal, with sizes less than 1000-km in the same orbital plane as the planets (the ecliptic) Comets (found throughout the Solar System): mostly water-ice, with sizes less than ~ 50-km majority are in the Oort cloud – spherical halo of comets about the Sun Long, elliptical orbits at any angle to ecliptic Kuiper belt objects (orbits beyond Neptune): ice and rock, with sizes up to a several 1000-km mostly in the same orbital plane as the planets

  13. Main belt Asteroid region A dwarf planet Not a dwarf Planet – not spherical

  14. Arrived at Vesta in 2011 Arrives at Ceres in 2015 NASA – Dawn Mission

  15. Japanese Space Agency Hayabusa Mission to study asteroid Itokawa [2005] Size: 535 x 294 x 209 m Sample return mission First directly sampled asteroid material returned to Earth 13 June 2010

  16. Main Belt Asteroids Near circular orbits about the Sun Located between Mars and Jupiter Many hundreds of thousands have been identified There are many more smaller asteroids than large ones: Collisionally evolved population Explains shapes (irregular), cratered surfaces and origin of meteorites

  17. Nature, Oct. 14, 2010 Discovered 6 January 2010 Located in the main belt asteroid region We are seeing the evolution of a collision event between two asteroids and their resultant rubble / dust trail

  18. Mimas Mars Earth Mercury Moon

  19. Asteroid fragments  production of craters on all Planets and Moons Deep Bay Carswell Gow Lake Saskatchewan craters Deep Bay Dia. = 13 km, age ~ 100 Ma Saskatoon Elbow Maple Creek Regina Viewfield K/T impact 65 million years ago Artists impression of asteroid impact

  20. Think about it The coal that presently powers Saskatchewan (and keeps us warm in the winter and the lights on at night) was formed because of an abrupt climate change induced by the impact of a massive (10-km wide) asteroid off the Yucatan Peninsula (Mexico) some 65 million years ago

  21. 200,000 AU Oort Cloud KB Kuiper Belt 20,000 AU Sun Pluto 40 AU The scale of the Solar System Oort Cloud – named after Jan Oort (1950) – vast reservoir of comets surrounding Sun (spherical halo of objects) Comets can enter the inner solar system at any angle From last class Kuiper Belt – named after Gerald Kuiper (1951) – disk like distribution of large ice / rock objects

  22. Meteorites: The Solar System on Earth

  23. Nantan Meteorite Observed fall in 1516? Finds relate to 1958 At least 9,500 kg of iron material fell and is scattered over 30 km2

  24. Meteorites: • Are small (meter-sized) fragments of material (rock and iron) ejected from the surface of asteroids during collisions • Survive passage through Earth’s atmosphere to be collected on the ground • Tell us about the composition of asteroids (rock and iron) and the first solid materials to form within the solar system • (Age of the solar system = 4.56 billion years) • Meteors – shooting stars: • Centimeter (and smaller) sized grains [derived from comets] that are totally destroyed during their passage through Earth’s atmosphere Taurid meteor seen from an airplane window Dust particle collected in Earth’s atmosphere Size ~ 0.1 mm

  25. Leonid meteors from Earth’s upper atmosphere

  26. The Earth is getting heavier … very slowly Annual accretion rate of dust and meteorites = 10,000,000 kg/year The sky is falling

  27. Halley’s comet – 1986 Orbital period ~ 75 yrs Range: 0.5 to 35 AU from Sun David Levy: “comets are like cats. They have tails and they do what they like”

  28. Dirty snowball model by Fred Whipple (1950) • Comet nucleus = water ice + embedded rocks + dust • and organic compounds • Nuclei typically a few kilometers in size • Ice / dust ratio ~ 2:1 even 1:1 (frozen dirt ball) • Dark inactive outer mantle surrounds the nucleus • Only ‘active’ over a few % of surface Cometary nuclei become active once they approach within ~ 1.5 AU of the Sun Solar heating  ice sublimation (ice  gas)  production of coma and tails  release of dust embedded in ice (1906 – 2004)

  29. Comet Hartley 2 P = 6.46 years a = 3.46 AU e = 0.694 4 November 2010 Deep Impact Spacecraft encounter Size: 2.25 x 0.5 km

  30. Blue color – emission from ionized CO molecules Sunlight reflected off small dust particles Length ~ 106 – 107 km Nucleus size ~ few km Bright spherical halo – sunlight reflected off gas and dust particles Diameter ~ 105 km Comet tails point away from the Sun

  31. Comet Hale-Bopp - 1996 Plasma tail – interaction with Sun’s magnetic field – blue color due to ionized carbon monoxide, CO+, molecule Coma Dust tail – sunlight reflected from small dust grains (meteoroids)

  32. Comet McNaught (2007) – comet tails point away from the Sun, but can also show remarkable structure

  33. Comet 21P/Giacobini-Zinner Very little dust – no Type II tail but prominent Type I tail Comet 67P/Churyumov-Gerasimenko A ‘dusty’ comet – no Type I tail ESA – Rosetta target (2015)

  34. Break-up of comet nuclei – a typical end phase + impact on planet or Sun SOHO spacecraft observations - UV light - comet is completely destroyed in Sun’s upper atmosphere, producing a CME Comet Elenin

  35. Cometary orbits are highly elliptical In contrast, asteroids & planetary orbits are nearly circular Deep Impact Mission

  36. 200,000 AU Oort Cloud KB Kuiper Belt 20,000 AU Sun Pluto 40 AU The scale of the Solar System Oort Cloud – named after Jan Oort (1950) – vast reservoir of comets surrounding Sun (spherical halo of objects) Comets can enter the inner solar system at any angle Kuiper Belt – named after Gerald Kuiper (1951) – disk like distribution of large ice / rock objects

  37. 200,000 AU Oort Cloud KB Kuiper Belt 20,000 AU Sun Pluto 40 AU The scale of the Solar System Oort Cloud – named after Jan Oort (1950) – vast reservoir of comets surrounding Sun (spherical halo of objects) Kuiper Belt – named after Gerald Kuiper (1951) – disk like distribution of large ice / rock objects (orbits are circular and in the ecliptic)

  38. 1992 QB1 The first KBO Discovered by Jane Luu and David Jewitt Orbital radius = 42 AU (2 AU beyond Pluto) Orbital period = 272.2 years Diameter ~ 280 km Composition: icy surface with a rocky core 20 min. 1.75 hr. 3.3 hr.

  39. The order of the planets www.orderoftheplanets.org/kuiper-belt.html

  40. Orbital motion of Triton Spin of Neptune Triton is believed to be a captured KBO in orbit around Neptune Reason = Triton orbits Neptune in The opposite sense to which Neptune spins – this suggests capture rather than formation by accretion

  41. Temperature ~ -230 o C Few craters, suggest active resurfacing Dark ‘steaks’ = Liquid nitrogen geysers (cryo-volcanism)

  42. Triton - a first glimpse of a KBO and Pluto? Voyager 2 Spacecraft images (1989) Above: frozen lake around an ice volcano? Left: South polar region showing a variety of frozen terrains. The pinkish colour is due to nitrogen frost New Horizons Mission arrives at Pluto in 2015 Dust to ice…. Clyde Tombaugh

  43. Pluto is followed in its orbit by numerous smaller objects – called Plutinos. This is why Pluto is a Dwarf Planet Moons of Pluto and Charon Charon discovered by James Christy in 1978 4th moon found July, 2011

  44. Distribution of Plutinos shown by red orbits Orbits of KBO objects shown in blue and black

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