Lecture 14: the Giant Planets, Their Moons, and Their Rings
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Exomoon Habitability Constrained by Illumination and Tidal Heating
submitted to Astrobiology: April 6, 2012 accepted by Astrobiology: September 8, 2012 published in Astrobiology: January 24, 2013 this updated draft: October 30, 2013 doi:10.1089/ast.2012.0859 Exomoon habitability constrained by illumination and tidal heating René HellerI , Rory BarnesII,III I Leibniz-Institute for Astrophysics Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany, [email protected] II Astronomy Department, University of Washington, Box 951580, Seattle, WA 98195, [email protected] III NASA Astrobiology Institute – Virtual Planetary Laboratory Lead Team, USA Abstract The detection of moons orbiting extrasolar planets (“exomoons”) has now become feasible. Once they are discovered in the circumstellar habitable zone, questions about their habitability will emerge. Exomoons are likely to be tidally locked to their planet and hence experience days much shorter than their orbital period around the star and have seasons, all of which works in favor of habitability. These satellites can receive more illumination per area than their host planets, as the planet reflects stellar light and emits thermal photons. On the contrary, eclipses can significantly alter local climates on exomoons by reducing stellar illumination. In addition to radiative heating, tidal heating can be very large on exomoons, possibly even large enough for sterilization. We identify combinations of physical and orbital parameters for which radiative and tidal heating are strong enough to trigger a runaway greenhouse. By analogy with the circumstellar habitable zone, these constraints define a circumplanetary “habitable edge”. We apply our model to hypothetical moons around the recently discovered exoplanet Kepler-22b and the giant planet candidate KOI211.01 and describe, for the first time, the orbits of habitable exomoons. -
Earth Venus Mercury the Sun Saturn Jupiter Uranus Mars
Mercury Diameter 1,391,000 km Diameter 4878 km Diameter 12,104 km Diameter 12,756 km Temperature 6000°C Temperature 427°C Temperature 482°C Temperature 22°C Speed 136 mph Speed 107,132 mph Speed 78,364 mph Speed 66,641 mph Mass 1,989,000 Mass 0.33 Mass 4.86 Mass 5.97 Year of Discovery N/A Year of Discovery Venus 1885 Year of Discovery N/A Year of Discovery N/A The Sun Mercury Earth Mercury is the closest planet to the sun, orbiting our star at an average distance of 57.9 million kilometres, taking 88 days to complete a trip around the sun. Mercury is also the smallest planet in our solar system. Mercury is the closest planet to the Sun, orbiting The Sun is the star at the centre of our Solar our star at an average distance of 57.9 million Venus is our neighbouring planet. It is Our home, some 4.5 billion years old. Life System. Its mass is approximately 330,000 times kilometres, taking 88 days to complete a trip impossible to state when Venus was appeared on the surface just 1 billion years heavier than our home planet and is 109 times around the sun. Mercury is also the smallest after creation, with human beings appearing wider. The Sun is the largest object in our Solar planet in our Solar System. discovered as it is visible with the just 200,000 years ago. System. naked eye. Diameter 6794 km Diameter 142,800 km Saturn Diameter 120,536 km Diameter 51,118 km Temperature -15°C Temperature -150°C Temperature -180°C Temperature -214°C Speed 53,980 mph Speed 29,216 mph Speed 21,565 mph Speed 15,234 mph Mass 0.64 Mass 1898 Mass 568 Mass 86.81 Mars Year of Discovery 1580 Year of Discovery 1610 Year of Discovery 700 BC Year of Discovery 1781 Jupiter Uranus The fourth planet from the Sun. -
7 Planetary Rings Matthew S
7 Planetary Rings Matthew S. Tiscareno Center for Radiophysics and Space Research, Cornell University, Ithaca, NY, USA 1Introduction..................................................... 311 1.1 Orbital Elements ..................................................... 312 1.2 Roche Limits, Roche Lobes, and Roche Critical Densities .................... 313 1.3 Optical Depth ....................................................... 316 2 Rings by Planetary System .......................................... 317 2.1 The Rings of Jupiter ................................................... 317 2.2 The Rings of Saturn ................................................... 319 2.3 The Rings of Uranus .................................................. 320 2.4 The Rings of Neptune ................................................. 323 2.5 Unconfirmed Ring Systems ............................................. 324 2.5.1 Mars ............................................................... 324 2.5.2 Pluto ............................................................... 325 2.5.3 Rhea and Other Moons ................................................ 325 2.5.4 Exoplanets ........................................................... 327 3RingsbyType.................................................... 328 3.1 Dense Broad Disks ................................................... 328 3.1.1 Spiral Waves ......................................................... 329 3.1.2 Gap Edges and Moonlet Wakes .......................................... 333 3.1.3 Radial Structure ..................................................... -
An Impacting Descent Probe for Europa and the Other Galilean Moons of Jupiter
An Impacting Descent Probe for Europa and the other Galilean Moons of Jupiter P. Wurz1,*, D. Lasi1, N. Thomas1, D. Piazza1, A. Galli1, M. Jutzi1, S. Barabash2, M. Wieser2, W. Magnes3, H. Lammer3, U. Auster4, L.I. Gurvits5,6, and W. Hajdas7 1) Physikalisches Institut, University of Bern, Bern, Switzerland, 2) Swedish Institute of Space Physics, Kiruna, Sweden, 3) Space Research Institute, Austrian Academy of Sciences, Graz, Austria, 4) Institut f. Geophysik u. Extraterrestrische Physik, Technische Universität, Braunschweig, Germany, 5) Joint Institute for VLBI ERIC, Dwingelo, The Netherlands, 6) Department of Astrodynamics and Space Missions, Delft University of Technology, The Netherlands 7) Paul Scherrer Institute, Villigen, Switzerland. *) Corresponding author, [email protected], Tel.: +41 31 631 44 26, FAX: +41 31 631 44 05 1 Abstract We present a study of an impacting descent probe that increases the science return of spacecraft orbiting or passing an atmosphere-less planetary bodies of the solar system, such as the Galilean moons of Jupiter. The descent probe is a carry-on small spacecraft (< 100 kg), to be deployed by the mother spacecraft, that brings itself onto a collisional trajectory with the targeted planetary body in a simple manner. A possible science payload includes instruments for surface imaging, characterisation of the neutral exosphere, and magnetic field and plasma measurement near the target body down to very low-altitudes (~1 km), during the probe’s fast (~km/s) descent to the surface until impact. The science goals and the concept of operation are discussed with particular reference to Europa, including options for flying through water plumes and after-impact retrieval of very-low altitude science data. -
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. -
Lecture 12 the Rings and Moons of the Outer Planets October 15, 2018
Lecture 12 The Rings and Moons of the Outer Planets October 15, 2018 1 2 Rings of Outer Planets • Rings are not solid but are fragments of material – Saturn: Ice and ice-coated rock (bright) – Others: Dusty ice, rocky material (dark) • Very thin – Saturn rings ~0.05 km thick! • Rings can have many gaps due to small satellites – Saturn and Uranus 3 Rings of Jupiter •Very thin and made of small, dark particles. 4 Rings of Saturn Flash movie 5 Saturn’s Rings Ring structure in natural color, photographed by Cassini probe July 23, 2004. Click on image for Astronomy Picture of the Day site, or here for JPL information 6 Saturn’s Rings (false color) Photo taken by Voyager 2 on August 17, 1981. Click on image for more information 7 Saturn’s Ring System (Cassini) Mars Mimas Janus Venus Prometheus A B C D F G E Pandora Enceladus Epimetheus Earth Tethys Moon Wikipedia image with annotations On July 19, 2013, in an event celebrated the world over, NASA's Cassini spacecraft slipped into Saturn's shadow and turned to image the planet, seven of its moons, its inner rings -- and, in the background, our home planet, Earth. 8 Newly Discovered Saturnian Ring • Nearly invisible ring in the plane of the moon Pheobe’s orbit, tilted 27° from Saturn’s equatorial plane • Discovered by the infrared Spitzer Space Telescope and announced 6 October 2009 • Extends from 128 to 207 Saturnian radii and is about 40 radii thick • Contributes to the two-tone coloring of the moon Iapetus • Click here for more info about the artist’s rendering 9 Rings of Uranus • Uranus -- rings discovered through stellar occultation – Rings block light from star as Uranus moves by. -
Planets of the Solar System
Chapter Planets of the 27 Solar System Chapter OutlineOutline 1 ● Formation of the Solar System The Nebular Hypothesis Formation of the Planets Formation of Solid Earth Formation of Earth’s Atmosphere Formation of Earth’s Oceans 2 ● Models of the Solar System Early Models Kepler’s Laws Newton’s Explanation of Kepler’s Laws 3 ● The Inner Planets Mercury Venus Earth Mars 4 ● The Outer Planets Gas Giants Jupiter Saturn Uranus Neptune Objects Beyond Neptune Why It Matters Exoplanets UnderstandingU d t di theth formationf ti and the characteristics of our solar system and its planets can help scientists plan missions to study planets and solar systems around other stars in the universe. 746 Chapter 27 hhq10sena_psscho.inddq10sena_psscho.indd 774646 PDF 88/15/08/15/08 88:43:46:43:46 AAMM Inquiry Lab Planetary Distances 20 min Turn to Appendix E and find the table entitled Question to Get You Started “Solar System Data.” Use the data from the How would the distance of a planet from the sun “semimajor axis” row of planetary distances to affect the time it takes for the planet to complete devise an appropriate scale to model the distances one orbit? between planets. Then find an indoor or outdoor space that will accommodate the farthest distance. Mark some index cards with the name of each planet, use a measuring tape to measure the distances according to your scale, and place each index card at its correct location. 747 hhq10sena_psscho.inddq10sena_psscho.indd 774747 22/26/09/26/09 111:42:301:42:30 AAMM These reading tools will help you learn the material in this chapter. -
Giant Planet Effects on Terrestrial Planet Formation and System Architecture
MNRAS 485, 541–549 (2019) doi:10.1093/mnras/stz385 Advance Access publication 2019 February 8 Giant planet effects on terrestrial planet formation and system architecture 1‹ 2 2,3 1 Anna C. Childs, Elisa Quintana, Thomas Barclay and Jason H. Steffen Downloaded from https://academic.oup.com/mnras/article-abstract/485/1/541/5309996 by NASA Goddard Space Flight Ctr user on 15 April 2020 1Department of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154, USA 2NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771, USA 3University of Maryland, Baltimore County, 1000 Hilltop Cir, Baltimore, MD 21250, USA Accepted 2019 February 4. Received 2019 January 16; in original form 2018 July 6 ABSTRACT Using an updated collision model, we conduct a suite of high-resolution N-body integrations to probe the relationship between giant planet mass and terrestrial planet formation and system architecture. We vary the mass of the planets that reside at Jupiter’s and Saturn’s orbit and examine the effects on the interior terrestrial system. We find that massive giant planets are more likely to eject material from the outer edge of the terrestrial disc and produce terrestrial planets that are on smaller, more circular orbits. We do not find a strong correlation between exterior giant planet mass and the number of Earth analogues (analogous in mass and semimajor axis) produced in the system. These results allow us to make predictions on the nature of terrestrial planets orbiting distant Sun-like star systems that harbour giant planet companions on long orbits – systems that will be a priority for NASA’s upcoming Wide-Field Infrared Survey Telescope (WFIRST) mission. -
Outer Planets: the Ice Giants
Outer Planets: The Ice Giants A. P. Ingersoll, H. B. Hammel, T. R. Spilker, R. E. Young Exploring Uranus and Neptune satisfies NASA’s objectives, “investigation of the Earth, Moon, Mars and beyond with emphasis on understanding the history of the solar system” and “conduct robotic exploration across the solar system for scientific purposes.” The giant planet story is the story of the solar system (*). Earth and the other small objects are leftovers from the feast of giant planet formation. As they formed, the giant planets may have migrated inward or outward, ejecting some objects from the solar system and swallowing others. The giant planets most likely delivered water and other volatiles, in the form of icy planetesimals, to the inner solar system from the region around Neptune. The “gas giants” Jupiter and Saturn are mostly hydrogen and helium. These planets must have swallowed a portion of the solar nebula intact. The “ice giants” Uranus and Neptune are made primarily of heavier stuff, probably the next most abundant elements in the Sun – oxygen, carbon, nitrogen, and sulfur. For each giant planet the core is the “seed” around which it accreted nebular gas. The ice giants may be more seed than gas. Giant planets are laboratories in which to test our theories about geophysics, plasma physics, meteorology, and even oceanography in a larger context. Their bottomless atmospheres, with 1000 mph winds and 100 year-old storms, teach us about weather on Earth. The giant planets’ enormous magnetic fields and intense radiation belts test our theories of terrestrial and solar electromagnetic phenomena. -
The Rings and Inner Moons of Uranus and Neptune: Recent Advances and Open Questions
Workshop on the Study of the Ice Giant Planets (2014) 2031.pdf THE RINGS AND INNER MOONS OF URANUS AND NEPTUNE: RECENT ADVANCES AND OPEN QUESTIONS. Mark R. Showalter1, 1SETI Institute (189 Bernardo Avenue, Mountain View, CA 94043, mshowal- [email protected]! ). The legacy of the Voyager mission still dominates patterns or “modes” seem to require ongoing perturba- our knowledge of the Uranus and Neptune ring-moon tions. It has long been hypothesized that numerous systems. That legacy includes the first clear images of small, unseen ring-moons are responsible, just as the nine narrow, dense Uranian rings and of the ring- Ophelia and Cordelia “shepherd” ring ε. However, arcs of Neptune. Voyager’s cameras also first revealed none of the missing moons were seen by Voyager, sug- eleven small, inner moons at Uranus and six at Nep- gesting that they must be quite small. Furthermore, the tune. The interplay between these rings and moons absence of moons in most of the gaps of Saturn’s rings, continues to raise fundamental dynamical questions; after a decade-long search by Cassini’s cameras, sug- each moon and each ring contributes a piece of the gests that confinement mechanisms other than shep- story of how these systems formed and evolved. herding might be viable. However, the details of these Nevertheless, Earth-based observations have pro- processes are unknown. vided and continue to provide invaluable new insights The outermost µ ring of Uranus shares its orbit into the behavior of these systems. Our most detailed with the tiny moon Mab. Keck and Hubble images knowledge of the rings’ geometry has come from spanning the visual and near-infrared reveal that this Earth-based stellar occultations; one fortuitous stellar ring is distinctly blue, unlike any other ring in the solar alignment revealed the moon Larissa well before Voy- system except one—Saturn’s E ring. -
The Solar System Cause Impact Craters
ASTRONOMY 161 Introduction to Solar System Astronomy Class 12 Solar System Survey Monday, February 5 Key Concepts (1) The terrestrial planets are made primarily of rock and metal. (2) The Jovian planets are made primarily of hydrogen and helium. (3) Moons (a.k.a. satellites) orbit the planets; some moons are large. (4) Asteroids, meteoroids, comets, and Kuiper Belt objects orbit the Sun. (5) Collision between objects in the Solar System cause impact craters. Family portrait of the Solar System: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, (Eris, Ceres, Pluto): My Very Excellent Mother Just Served Us Nine (Extra Cheese Pizzas). The Solar System: List of Ingredients Ingredient Percent of total mass Sun 99.8% Jupiter 0.1% other planets 0.05% everything else 0.05% The Sun dominates the Solar System Jupiter dominates the planets Object Mass Object Mass 1) Sun 330,000 2) Jupiter 320 10) Ganymede 0.025 3) Saturn 95 11) Titan 0.023 4) Neptune 17 12) Callisto 0.018 5) Uranus 15 13) Io 0.015 6) Earth 1.0 14) Moon 0.012 7) Venus 0.82 15) Europa 0.008 8) Mars 0.11 16) Triton 0.004 9) Mercury 0.055 17) Pluto 0.002 A few words about the Sun. The Sun is a large sphere of gas (mostly H, He – hydrogen and helium). The Sun shines because it is hot (T = 5,800 K). The Sun remains hot because it is powered by fusion of hydrogen to helium (H-bomb). (1) The terrestrial planets are made primarily of rock and metal.