Planets of the Solar System
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The Multifaceted Planetesimal Formation Process
The Multifaceted Planetesimal Formation Process Anders Johansen Lund University Jurgen¨ Blum Technische Universitat¨ Braunschweig Hidekazu Tanaka Hokkaido University Chris Ormel University of California, Berkeley Martin Bizzarro Copenhagen University Hans Rickman Uppsala University Polish Academy of Sciences Space Research Center, Warsaw Accumulation of dust and ice particles into planetesimals is an important step in the planet formation process. Planetesimals are the seeds of both terrestrial planets and the solid cores of gas and ice giants forming by core accretion. Left-over planetesimals in the form of asteroids, trans-Neptunian objects and comets provide a unique record of the physical conditions in the solar nebula. Debris from planetesimal collisions around other stars signposts that the planetesimal formation process, and hence planet formation, is ubiquitous in the Galaxy. The planetesimal formation stage extends from micrometer-sized dust and ice to bodies which can undergo run-away accretion. The latter ranges in size from 1 km to 1000 km, dependent on the planetesimal eccentricity excited by turbulent gas density fluctuations. Particles face many barriers during this growth, arising mainly from inefficient sticking, fragmentation and radial drift. Two promising growth pathways are mass transfer, where small aggregates transfer up to 50% of their mass in high-speed collisions with much larger targets, and fluffy growth, where aggregate cross sections and sticking probabilities are enhanced by a low internal density. A wide range of particle sizes, from mm to 10 m, concentrate in the turbulent gas flow. Overdense filaments fragment gravitationally into bound particle clumps, with most mass entering planetesimals of contracted radii from 100 to 500 km, depending on local disc properties. -
Multiple Asteroid Systems: Dimensions and Thermal Properties from Spitzer Space Telescope and Ground-Based Observations*
Multiple Asteroid Systems: Dimensions and Thermal Properties from Spitzer Space Telescope and Ground-Based Observations* F. Marchisa,g, J.E. Enriqueza, J. P. Emeryb, M. Muellerc, M. Baeka, J. Pollockd, M. Assafine, R. Vieira Martinsf, J. Berthierg, F. Vachierg, D. P. Cruikshankh, L. Limi, D. Reichartj, K. Ivarsenj, J. Haislipj, A. LaCluyzej a. Carl Sagan Center, SETI Institute, 189 Bernardo Ave., Mountain View, CA 94043, USA. b. Earth and Planetary Sciences, University of Tennessee 306 Earth and Planetary Sciences Building Knoxville, TN 37996-1410 c. SRON, Netherlands Institute for Space Research, Low Energy Astrophysics, Postbus 800, 9700 AV Groningen, Netherlands d. Appalachian State University, Department of Physics and Astronomy, 231 CAP Building, Boone, NC 28608, USA e. Observatorio do Valongo/UFRJ, Ladeira Pedro Antonio 43, Rio de Janeiro, Brazil f. Observatório Nacional/MCT, R. General José Cristino 77, CEP 20921-400 Rio de Janeiro - RJ, Brazil. g. Institut de mécanique céleste et de calcul des éphémérides, Observatoire de Paris, Avenue Denfert-Rochereau, 75014 Paris, France h. NASA Ames Research Center, Mail Stop 245-6, Moffett Field, CA 94035-1000, USA i. NASA/Goddard Space Flight Center, Greenbelt, MD 20771, United States j. Physics and Astronomy Department, University of North Carolina, Chapel Hill, NC 27514, U.S.A * Based in part on observations collected at the European Southern Observatory, Chile Programs Numbers 70.C-0543 and ID 72.C-0753 Corresponding author: Franck Marchis Carl Sagan Center SETI Institute 189 Bernardo Ave. Mountain View CA 94043 USA [email protected] Abstract: We collected mid-IR spectra from 5.2 to 38 µm using the Spitzer Space Telescope Infrared Spectrograph of 28 asteroids representative of all established types of binary groups. -
Formation of the Solar System (Chapter 8)
Formation of the Solar System (Chapter 8) Based on Chapter 8 • This material will be useful for understanding Chapters 9, 10, 11, 12, 13, and 14 on “Formation of the solar system”, “Planetary geology”, “Planetary atmospheres”, “Jovian planet systems”, “Remnants of ice and rock”, “Extrasolar planets” and “The Sun: Our Star” • Chapters 2, 3, 4, and 7 on “The orbits of the planets”, “Why does Earth go around the Sun?”, “Momentum, energy, and matter”, and “Our planetary system” will be useful for understanding this chapter Goals for Learning • Where did the solar system come from? • How did planetesimals form? • How did planets form? Patterns in the Solar System • Patterns of motion (orbits and rotations) • Two types of planets: Small, rocky inner planets and large, gas outer planets • Many small asteroids and comets whose orbits and compositions are similar • Exceptions to these patterns, such as Earth’s large moon and Uranus’s sideways tilt Help from Other Stars • Use observations of the formation of other stars to improve our theory for the formation of our solar system • Use this theory to make predictions about the formation of other planetary systems Nebular Theory of Solar System Formation • A cloud of gas, the “solar nebula”, collapses inwards under its own weight • Cloud heats up, spins faster, gets flatter (disk) as a central star forms • Gas cools and some materials condense as solid particles that collide, stick together, and grow larger Where does a cloud of gas come from? • Big Bang -> Hydrogen and Helium • First stars use this -
The Subsurface Habitability of Small, Icy Exomoons J
A&A 636, A50 (2020) Astronomy https://doi.org/10.1051/0004-6361/201937035 & © ESO 2020 Astrophysics The subsurface habitability of small, icy exomoons J. N. K. Y. Tjoa1,?, M. Mueller1,2,3, and F. F. S. van der Tak1,2 1 Kapteyn Astronomical Institute, University of Groningen, Landleven 12, 9747 AD Groningen, The Netherlands e-mail: [email protected] 2 SRON Netherlands Institute for Space Research, Landleven 12, 9747 AD Groningen, The Netherlands 3 Leiden Observatory, Leiden University, Niels Bohrweg 2, 2300 RA Leiden, The Netherlands Received 1 November 2019 / Accepted 8 March 2020 ABSTRACT Context. Assuming our Solar System as typical, exomoons may outnumber exoplanets. If their habitability fraction is similar, they would thus constitute the largest portion of habitable real estate in the Universe. Icy moons in our Solar System, such as Europa and Enceladus, have already been shown to possess liquid water, a prerequisite for life on Earth. Aims. We intend to investigate under what thermal and orbital circumstances small, icy moons may sustain subsurface oceans and thus be “subsurface habitable”. We pay specific attention to tidal heating, which may keep a moon liquid far beyond the conservative habitable zone. Methods. We made use of a phenomenological approach to tidal heating. We computed the orbit averaged flux from both stellar and planetary (both thermal and reflected stellar) illumination. We then calculated subsurface temperatures depending on illumination and thermal conduction to the surface through the ice shell and an insulating layer of regolith. We adopted a conduction only model, ignoring volcanism and ice shell convection as an outlet for internal heat. -
The Acceler the Accelerating Circulation of Jupiter's Great Red
The accelerating circulation of Jupiter’s Great Red Spot John H. Rogers A report of the Jupiter Section (Director: John H. Rogers) Jupiter’s Great Red Spot (GRS) has been evolving, with fluctuations, since it was first observed in the 19th century. It has shown trends of decreasing length, decelerating drift rate, and possibly accelerating internal circulation. This paper documents how these trends have pro- gressed since the time of the Voyager encounters in 1979, up to 2006, from ground-based amateur observations.1 The trends in length and drift rate have continued; the GRS is now smaller than ever before.2 The internal circulation period was directly measured in 2006 for the first time since the Voyager flybys, and is now 4.5 days, which confirms that the period is shortening.3 In contrast, the 90-day oscillation of the GRS in longitude continues unchanged, and may be accompanied by a very small oscillation in latitude. Introduction =–110, +105°/month: the mean speed of the SEBs and STBn jets) through 63 m/s (DL2 = +130°/month: the mean speed of the SEBs jet when a STropD is present) to 110–140 m/s (the The Great Red Spot (GRS) is a giant anticyclone in Jupiter’s maximum internal wind speed recorded in the Voyager im- atmosphere, circulating anticlockwise, with winds that are ages: Table 1a). Images by the Galileo Orbiter in 2000 re- among the most rapid in the solar system (see reference 1, corded a further acceleration to ~145–190 m/s.11,12 pp.188-197). The circulation was already suspected in the These wind speeds were derived by tracking small cloud early 20th century (ref.1, p.256), and the first tentative obser- tracers over short intervals in spacecraft images. -
Amplify Science Earth's Changing Climate
Lawrence Hall of Science has new instructional materials that address the Next Generation Science Standards! Check out these Middle School Units… As just one example, compare Middle School units from three different Hall programs. See for yourself how each program goes about addressing the Middle School NGSS Standards related to Human Impacts and Climate Change, and choose the approach that best meets the needs of your school district. MS NGSS Performance Expectations: Human Impacts and Climate Change • MS-ESS3-2. Analyze and interpret data on natural hazards to forecast future catastrophic events and inform the development of technologies to mitigate their effects. • MS-ESS3-3. Apply scientific principles to design a method for monitoring and minimizing a human impact on the Environment. • MS-ESS3-4. Construct an argument supported by evidence for how increases in human population and per-capita consumption of natural resources impact Earth’s systems. • MS-ESS3-5. Ask questions to clarify evidence of the factors that have caused the rise in global temperatures over the past century. Sample Units from Three Different Hall Programs • Amplify Science—Earth’s Changing Climate: Vanishing Ice Earth’s Changing Climate Engineering Internship • FOSS—Weather and Water • Ocean Sciences Sequence—The Ocean-Atmosphere Connection and Climate Change ©The Regents of the University of California ©The Regents of the University of California Description of two Middle School units from Amplify Science Earth’s Changing Climate: Vanishing Ice and Earth’s Changing Climate Engineering Internship Grade 6-8 Units — requiring at least 19 and 10 45-minute class sessions respectively (two of 27 Middle School Amplify Science units) The Problem: Why is the ice on Earth’s surface melting? Students’ Role: In the role of student climatologists, students investigate what is causing ice on Earth’s surface to melt in order to help the fictional World Climate Institute educate the public about the processes involved. -
Chapter 9: the Origin and Evolution of the Moon and Planets
Chapter 9 THE ORIGIN AND EVOLUTION OF THE MOON AND PLANETS 9.1 In the Beginning The age of the universe, as it is perceived at present, is perhaps as old as 20 aeons so that the formation of the solar system at about 4.5 aeons is a comparatively youthful event in this stupendous extent of time [I]. Thevisible portion of the universe consists principally of about 10" galaxies, which show local marked irregularities in distribution (e.g., Virgo cluster). The expansion rate (Hubble Constant) has values currently estimated to lie between 50 and 75 km/sec/MPC [2]. The reciprocal of the constant gives ages ranging between 13 and 20 aeons but there is uncertainty due to the local perturbing effects of the Virgo cluster of galaxies on our measurement of the Hubble parameter [I]. The age of the solar system (4.56 aeons), the ages of old star clusters (>10" years) and the production rates of elements all suggest ages for the galaxy and the observable universe well in excess of 10" years (10 aeons). The origin of the presently observable universe is usually ascribed, in current cosmologies, to a "big bang," and the 3OK background radiation is often accepted as proof of the correctness of the hypothesis. Nevertheless, there are some discrepancies. The observed ratio of hydrogen to helium which should be about 0.25 in a "big-bang" scenario may be too high. The distribution of galaxies shows much clumping, which would indicate an initial chaotic state [3], and there are variations in the spectrum of the 3OK radiation which are not predicted by the theory. -
Planet Formation
3. Planet form ation Frontiers of A stronom y W orkshop/S chool Bibliotheca A lexandrina M arch-A pril 2006 Properties of planetary system s • all giant planets in the solar system have a > 5 A U w hile extrasolar giant planets have semi-major axes as small as a = 0.02 A U • planetary orbital angular momentum is close to direction of S un’s spin angular momentum (w ithin 7o) • 3 of 4 terrestrial planets and 3 of 4 giant planets have obliquities (angle betw een spin and orbital angular momentum) < 30o • interplanetary space is virtually empty, except for the asteroid belt and the Kuiper belt • planets account for < 0.2% of mass of solar system but > 98% of angular momentum Properties of planetary system s • orbits of major planets in solar system are nearly circular (eMercury=0.206, ePluto=0.250); orbits of extrasolar planets are not (emedian=0.28) • probability of finding a planet is proportional to mass of metals in the star Properties of planetary system s • planets suffer no close encounters and are spaced fairly n regularly (Bode’s law : an=0.4 + 0.3×2 ) planet semimajor axis (A U ) n an (A U ) Mercury 0.39 −∞ 0.4 V enus 0.72 0 0.7 Earth 1.00 1 1.0 Mars 1.52 2 1.6 asteroids 2.77 (Ceres) 3 2.8 Jupiter 5.20 4 5.2 S aturn 9.56 5 10.0 U ranus 19.29 6 19.6 N eptune 30.27 7 38.8 Pluto 39.68 8 77.2 Properties of planetary system s • planets suffer no close encounters and are spaced fairly n regularly (Bode’s law : an=0.4 + 0.3×2 ) planet semimajor axis (A U ) n an (A U ) Mercury+ 0.39 −∞ 0.4 V enus 0.72 0 0.7 Earth 1.00 1 1.0 *predicted -
Jupiter's “Red Spot Jr.”
National Aeronautics and Space Administration Jupiter’s “Red Spot Jr.” Astronomers Watch the Birth of a Monster Storm Monstrous hurricanes on Earth can stretch across in the close-up image are clouds being shaped by the entire eastern United States. These storms, how- high-speed winds. ever, would be considered timid on Jupiter, where an On Earth, meteorologists routinely watch hur- oval-shaped spot about the size of Earth has recently ricanes form off the African coast, sweep across the emerged. Dubbed Red Spot Jr., this gigantic storm is Atlantic Ocean, and fall apart when they reach the only the little brother of Jupiter’s trademark Great Red colder waters of the northern Atlantic. Astronomers, Spot. however, rarely get the chance to witness the birth of The Great Red Spot is a mammoth oval disturbance storms on our solar system neighbors. Other planets that is so large it could swallow nearly three Earths. are far away from Earth, so astronomers need power- First spotted in 1664 by Robert Hooke, the storm has ful telescopes like the Hubble Space Telescope to been raging on the planet for at least 342 years. track planetary weather. Storms on other planets also Red Spot Jr. is the first storm that astronomers may take years to form. watched develop on a gas giant planet. The huge spot Amateur and professional astronomers eagerly formed between 1998 and 2000, when three small, watched the emerging new red spot. Months later, white, oval-shaped storms merged together. Two of Hubble snapped the first detailed images of Red Spot the white spots have been observed since about 1915, Jr. -
Workshop on Analysis of Returned Comet Nucleus Samples
WORKSHOP ON Analysis of Returned Comet Nucleus Samples JANUARY 16-18,1989 MILPITAS, CALIFORNIA SPONSORED BY LUNAR AND PLANETARY INSTITUTE NASA AMES RESEARCH CENTER WORKSHOP ON Analysis of Returned Comet Nucleus Samples JANUARY 16-18, 1989 MILPITAS, CALIFORNIA SPONSORED BY LUNAR AND PLANETARY INSTITUTE NASA AMES RESEARCH CENTER Cover photo courtesy of H. U. Keller. Copyright held by Max-Planck-Jnstitut fur Aeronomie, Lindau- Katlenburg, FRG. Available from the Lunar and Planetary Institute as part of the Comet Halley image sequence ( #C3443 ). PROGRAM COMMITI'EE MEMBERS Thomas Ahrens Eberhard Gri.in California Institute of Technology Max-Planck-Institut filr Kemphysik Lou Allamandola Martha Hanner NASA Ames Research Center let Propulsion Laboratory David Blake Alan Harris (Ex Officio) NASA Ames Research Center let Propulsion Laboratory Donald Brownlee John Kerridge University of Washington University of California, Los Angeles Theodore E. Bunch Yves Langevin NASA Ames Research Center Universite de Paris, Sud Humberto Campins Larry Nyquist, Convener Planetary Science Institute NASA Johnson Space Center Sherwood Chang, Convener Gerhard Schwehm NASA Ames Research Center European Space Agency, ESTEC JeffCuzzi Paul Weissman NASA Ames Research Center Jet Propulsion Laboratory Monday. .Januacy 16th 7:00 - 8:00 a.m. Registration 8:00a.m. Welcome & Introduction to Workshop Sherwood Chang, NASA, Ames Research Center 8:10a.m. Rosetta - Comet Nucleus Sample Return Mission: Status Report Geoffrey Briggs, NASA Headquarters Dr. Marcello Coradini, European Space Agency SESSION lA Chairman: Sherwood Chang 8:30a.m. - 12:00 Noon SOURCES AND NATURE OF COMETARY COMPONENTS Invited Speaker Presentations Nuclear Synthesis and Isotopic Composition of Insteller Grains Alexander Tielens Interstellar and Cometary Dust John Mathis Refractory Solids in Chondrites and Comets: How Similar? John Wood 10:30 a.m. -
Meteorites and the Origin of the Solar System
Meteorites and the origin of the solar system STEPHEN G. BRUSH University of Maryland, College Park, MD 20742, USA (e-mail: [email protected]) Abstract: During the past two centuries, theories of the origin of the solar system have been strongly influenced by observations and theories about meteorites. I review this history up to about 1985. During the 19th century the hypothesis that planets formed by accretion of small solid particles ('the meteoritic hypothesis') competed with the alternative 'nebular hypothesis' of Laplace, based on condensation from a hot gas. At the beginning of the 20th century Chamberlin and Moulton revived the meteoritic hypothesis as the 'planetesimal hypothesis' and joined it to the assumption that the solar system evolved from the encounter of the Sun with a passing star. Later, the encounter hypothesis was rejected and the planetesimal hypothesis was incorporated into new versions of the nebular hypothesis. In the 1950s, meteorites provided essential data for the establishment by Patterson and others of the pre- sently accepted 4500 Ma age of the Earth and the solar system. Analysis of the Allende meteorite, which fell in 1969, inspired the 'supernova trigger' theory of the origin of the solar system, and furnished useful constraints on theories of planetary formation developed by Urey, Ringwood, Anders and others. Many of these theories assumed condensation from a homogeneous hot gas, an assumption that was challenged by astrophysical calculations. The meteoritic-planetesimal theory of planet formation was developed in Russia by Schmidt and later by Safronov. Wetherill, in the United States, established it as the preferred theory for formation of terrestrial planets. -
Earth Science SCIH 041 055 Credits: 0.5 Units / 5 Hours / NCAA
UNIVERSITY OF NEBRASKA HIGH SCHOOL Earth Science SCIH 041 055 Credits: 0.5 units / 5 hours / NCAA Course Description Have you ever wondered where marble comes from? or how deep the ocean is? or why it rains more in areas near the Equator than in other places? In this course students will study a variety of topics designed to give them a better understanding of the planet on which we live. They will study the composition of Earth including minerals and different rock types, weathering and erosion processes, mass movements, and surface and groundwater. They will also explore Earth's atmosphere and oceans, including storms, climate and ocean movements, plate tectonics, volcanism, earthquakes, mountain building, and geologic time. This course concludes with an in-depth look at the connections between our Earth's vast resources and the human population's dependence and impact on them. Graded Assessments: 5 Unit Evaluations; 2 Projects; 2 Proctored Progress Tests, 5 Teacher Connect Activities Course Objectives When you have completed the materials in this course, you should be able to: 1. Describe how Earth materials move through geochemical cycles (carbon, nitrogen, oxygen) resulting in chemical and physical changes in matter. 2. Understand the relationships among Earth’s structure, systems, and processes. 3. Describe how heat convection in the mantle propels the plates comprising Earth’s surface across the face of the globe (plate tectonics). 4. Evaluate the impact of human activity and natural causes on Earth’s resources (groundwater, rivers, land, fossil fuels). 5. Describe the relationships among the sources of energy and their effects on Earth’s systems.