* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Aim of this course: Course Outline
Survey
Document related concepts
Exploration of Io wikipedia , lookup
Scattered disc wikipedia , lookup
Planet Nine wikipedia , lookup
Exploration of Jupiter wikipedia , lookup
Kuiper belt wikipedia , lookup
Sample-return mission wikipedia , lookup
Interstellar probe wikipedia , lookup
Eris (dwarf planet) wikipedia , lookup
History of Solar System formation and evolution hypotheses wikipedia , lookup
Space: 1889 wikipedia , lookup
Naming of moons wikipedia , lookup
Formation and evolution of the Solar System wikipedia , lookup
Planets beyond Neptune wikipedia , lookup
Transcript
Aim of this course: The Terrestrial Planets Lecture 1: Introduction Provide a general introduction to the four terrestrial (Earth-like) planets (Mercury, Venus, Earth and Mars). By the end you should be able to identify their major features and their common or unique properties. ? The Terrestrial planets at correct relative size: Mercury Course Outline Lecture 1 Lecture 2 Lecture 3 Lecture 4 Lecture 5 Lecture 6 Lecture 7 Lecture 8 Introduction Earth – interior Earth – atmosphere Venus – Earth’s twin? Mars – dead or alive? Mercury – dense and hot The Moon – properties & origin Summary & Planet Formation Venus Earth Mars Course books, handouts and the WWW Listed textbook for this course: “Discovering the Solar System” by Barrie W. Jones Good for detail and if doing several planet courses Any modern introductory astronomy text – e.g. “Astronomy Today” by Chaisson & McMillan On-line: brief summary handout (as given out today) and (incomplete – images and tables) copies of each lecture, at http://www.star.le.ac.uk/pto2/planets.html You need to take notes of text material during lectures 1 MANY web pages – some recommended examples: http://nineplanets.org A multimedia tour of the Solar System. http://www.solarviews.com/eng/ Another multimedia experience. Quiz: name the 10 largest objects in the Solar System (excluding the Sun) Jupiter Saturn 71490 km 60270 km Uranus 25560 km Neptune 24765 km Earth 6378 km http://exoplanet.eu An excellent site for information on extra-solar planets. Venus 6052 km http://www.nasm.si.edu/apollo/ Site for information on the Apollo missions to The Moon. Mars Ganymede 3397 km 2635 km (Moon of Jupiter) Titan Mercury 2575 km (Moon of Saturn) 2440 km Introducing the Solar System 2 What is in the Solar System? Sun, planets, moons, asteroids, comets, dust… The Planets • The planets orbit counterclockwise in the Ecliptic plane • Orbits are ellipses, with Sun at one focus – most with small eccentricity (e) (orbits obey Kepler’s Laws) • Earth orbits Sun at mean distance of one “Astronomical Unit” Sun = 99.85% of mass Comet West Eros • Mercury’s orbit (and Pluto) has a significant eccentricity and inclination (angle from Ecliptic plane) Dust ? Planets = 0.135% of mass! Planetary data Asteroids – interplanetary debris • Over 100,000 known - most between Mars and Jupiter (>100m are asteroids; rest are meteroids) Planet Orbital semi-major axis (AU) Orbital Period (years) Mass (Earths) Diameter (Earths) Average Density (kg/m³) Mercury 0.387 0.241 0.055 0.383 5430 • Total mass < 0.05 x Moon. Largest is Ceres (940 km) Venus 0.723 0.615 0.815 0.949 5240 • Earth-crossing Earth 1.000 1.000 1.000 1.000 5520 • Source Mars 1.524 1.881 0.107 0.533 3940 Jupiter 5.203 11.86 317.83 11.21 1330 Saturn 9.555 29.42 95.16 9.45 700 Uranus 19.22 83.75 14.50 4.01 1300 Neptune 30.11 163.7 17.20 3.88 1760 Pluto 39.54 248.0 0.0025 0.180 2100 asteroids are of great interest! of most meterorites/meteors Iron & Nickel – rare, similar to type M asteroids Chondrite – similar to terrestial mantle/crust 3 NASA Near Earth Asteroid Rendezvous Mission NASA Stardust Mission Principal target: asteroid Eros Arrived late 1998; landed Feb. 12 2001 Target: Comet Wild 2 Landing image: Distance 250 m Image = size of lecture room View from 500 km – looks like an asteroid surface East and West hemispheres Size 33 x 13 x 13 km Big craters, grooves, then smaller craters – get evolutionary sequence from surface features The Kuiper Belt and Pluto (&TNOs) Left image: short exposure - see craters, boulders etc. Right image: long exposure - see dust jets Pluto ~1010 Kuiper belt: icy objects beyond Neptune (30–1000 AU) Pluto is a large example. Quaoar discovered in 2002 – half the size of Pluto. Other large objects found since (e.g. Sedna; 2003 UB313 (Eris)). See changes in colour over time and in mass of atmosphere. May be due to melting/warming of nitrogen ice. 4 Is Pluto a planet? Question: Should other large objects at similar distances to Pluto (including Pluto) also be called planets? All are in inclined, eccentric orbits with periods of 300-600 years. Several have moons. Eris and Dysnomia Eris is the Greek goddess of strife and discord. Her child, Dysnomia, is the goddess of Lawlessness. Dysnomia’s orbit allows for an accurate mass estimate: M(Eris) = 1.27 x M(Pluto) Where is Eris? IAU resolutions 2006 (or, how to lose friends and influence nobody) Eris density (~2.5 kg m-3) similar to Pluto (~1.8 kg m-3) (low compared to Earth) IAU resolutions 2006 (or, how to lose friends and influence nobody) 5A. The IAU therefore resolves that "planets" and other bodies in our Solar System, except satellites, be defined into three distinct categories in the following way: 5A. The IAU therefore resolves that "planets" and other bodies in our Solar System, except satellites, be defined into three distinct categories in the following way: (1) A "planet" is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit. (1) A "planet" is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit. (2) A "dwarf planet" is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape , (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite. (2) A "dwarf planet" is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape , (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite. (3) All other objects except satellites orbiting the Sun shall be referred to collectively as "Small Solar-System Bodies". (3) All other objects except satellites orbiting the Sun shall be referred to collectively as "Small Solar-System Bodies". 6A. The IAU further resolves: 6A. The IAU further resolves: Pluto is a "dwarf planet" by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects. Pluto is a "dwarf planet" by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects. 5 The Oort cloud Extends to 100,000 AU with total mass = 30 x Earth 4th October 1957 Sputnik 1 launched 27th August 1962 Mariner 2 - the first interplanetary craft flies to Venus 6 20th July 1969 Apollo 11 lands on Moon 29th March 1974 Mariner 10 reaches Mercury Messenger flyby 1,2,3: Feb. 14 & Oct. 6 2008, Sept. 29 2009 July 1976 Viking landers touch down on Mars 20th August 1977 Voyager 2 launched 5th September 1977 Voyager 1 launched No Martians seen… Followed Pioneer missions (launched 1972/73) to Jupiter 7 Voyager mission used “Gravitational slingshot” 1981 Voyager 2 image of Saturn. Voyager finds 3 new moons and complex structure in the rings July 1979 Voyagers discover Volcanism on Io and 3 new moons of Jupiter January 1986 Voyager 2 reaches Uranus. Finds 10 moons and measures a magnetic field 8 August 1989 Voyager 2 passes Neptune, finding 6 moons and geysers on Triton 1990-1994 Magellan maps Venus Feb 14 1990 Voyager 1 portrait of the Solar System September 1992 First Kuiper Belt Object discovered 9 1995 First extra-solar planet discovered by Michel Mayor and Didier Queloz 15th October 1997 Cassini-Huygens mission to Saturn launched – arrived July 2004 December 7th 1995 Galileo drops probe into Jupiter Probe entered atmosphere at 106,000 mph (x100 rifle bullet) January 2004 ESA Mars Express image of Gusev crater + image from NASA Spirit rover Saturn and Titan from 285 million km 10 Cassini (Saturn) & Huygens probe (2005, Titan) Deep Impact – Comet Tempel 1: 2005 July 4 Surface image View from 8km up Huygens probe release into Titan First extra-solar planet imaged: 2008 Kepler planets February 2011 Planet roughly x3 mass of Jupiter but orbits at a distance of 115 AU (about x20 distance of Jupiter ) 11 Selected Missions Messenger (2004; arrived 2011) Bepi-Colombo (2016; arrives 2024) NASA mission to Mercury Rosetta (2004) ESA mission to visit comets Venus Express (2005) ESA+Japan mission to Mercury ESA mission to Venus Corot (France/ESA) (2006) Kepler (NASA) (2009) Search for extra-solar planets New Horizons Mission (2006) NASA mission to visit Pluto (2015) and the Kuiper belt The End 12