Vulcanoids by Landon Curt Noll

Total Page:16

File Type:pdf, Size:1020Kb

Vulcanoids by Landon Curt Noll Searching for Vulcanoids by LANDON CURT NOLL the title of this article may sound like an episode from Star Trek, but to astron- omers, this is an inner-solar-system quest that has been in the making since 1859. It’s a quest that you can join today! Hunting for minor planets The innermost region of our solar system is known as the Vulcanoid zone, and it has remained largely unexplored. (Even Mercury has been only partially during a total solar eclipse photographed by just one spacecraft, Mariner 10, and that was in the mid-1970s.) Discovering asteroids lurking in the Vulcanoid zone would greatly add to our is not as far-fetched as it understanding of the birth and evolution of our solar system — not to mention those of other Sun-like stars in the Milky Way. may seem. The biggest challenge in searching for Vulcanoids is the intense glare from the Sun. A total solar eclipse, such as the one occurring on March 29th (see page 115), offers an excellent, albeit brief, opportunity to probe this normally hidden zone. With the advent of inexpensive CCDs, powerful image-processing software, and the Internet, amateur astronomers are now in a position to exploit the short window into the Sun’s inner sanctum that a total eclipse provides. What is this Vulcan stuff all about? In the mid-19th century, French astronomer Urbain J. J. Le Verrier demon- strated that Mercury’s motion around the Sun was not behaving as prescribed by Newtonian mechanics. In 1859 Le Verrier proposed that the gravitational effect of a small inner planet, which he later named “Vulcan,” could account for Mercury’s unusual motion, and the search was on (S&T: October 1998, page 112). Not until 1916 did Einstein’s general theory of relativity finally explain Mercury’s motion, and searches for the putative intra-Mercurial planet (perhaps several such bodies) were largely abandoned. Today we know of no sizable object that per- manently occupies the space inside Mercury’s orbit. Nevertheless, This artwork by planetary scientist Daniel D. Durda (Southwest many astronomers still Research Institute) depicts how a Vulcanoid might look as it refer to this region as orbits the Sun. Vulcanoids are thought to be a possible popula- the Vulcanoid zone, be- tion of small asteroids residing well inside the orbit of Mercury (shown here as the bright “star” in the background). cause of its association with the mythical planet Vulcan. A minor planet whose mean distance to the Sun is less than that of Mercury (0.387 astro- nomical unit, or 57.9 mil- lion kilometers) would be considered residing within the Vulcanoid zone. Due to the intense 26 ECLIPSE 2009 heat of the Sun in this region, the Durda and S. Alan Stern (Southwest rizon (ignoring small obstructions only objects astronomers expect to Research Institute) suggest that along the horizon, such as trees, find here are asteroids. Vulcanoids are most likely to reside houses, and hills). Your test images Why is it important to participate toward the 0.18-a.u. edge of the zone, will help you determine the optimum in this search? You have a chance to and that the gravitational pull of exposure time to use during the become part of astronomical history. Mercury and the other planets could eclipse. (Taking an exposure while With a bit of effort and luck, you nudge the orbits of these bodies out part of the Sun’s disk is uncovered could be among those to find the very from the ecliptic plane by as much as could saturate the CCD, so plan to first Vulcanoids! 10° or more. have a 4-second margin of safety on In 2000, a team led by Durda used either side of the length of totality.) Modern Vulcanoid theory images from the Large Recent models by Neil Wyn W. Angle and Spectrometric Evans (University of Oxford) and Coronagraph aboard the Serge A. Tabachnik (Princeton Solar and Heliospheric University Observatory) suggest that Observatory (SOHO) space- Vulcanoid asteroids, if they exist, craft to conduct the most must reside in a narrow, dynamically extensive search to date for stable band in the Vulcanoid zone, Vulcanoids as faint as mag- close to the ecliptic. Recent updates nitude +8.0 (S&T: August to their model suggest that objects 2000, page 26). Although closer than 0.08 a.u. to the Sun would the team failed to find a be perturbed by extreme solar heat- single one, the existence ing and dynamical transport mecha- of fainter Vulcanoids is nisms and would either be pushed clearly a possibility. If the away or pulled in toward the Sun. largest Vulcanoids are just Mercury and the other planets under the search limits place an additional constraint on the (that is, between 20 and 60 stability of the Vulcanoid zone; Evans km in diameter), then the and Tabachnik’s latest model sug- team estimates that there gests that a Vulcanoid with a mean could be as many as 1,800 distance greater than 0.18 a.u. would to 42,000 Vulcanoids larger This view of the Sun’s corona and its surroundings was be ejected from the zone. Thus, any than 1 km! captured by the Large Angle and Spectrometric Coronagraph aboard the Solar and Heliospheric Observa- long-term Vulcanoid asteroid should finding Vulcanoids tory (SOHO) spacecraft on New Year’s Day 2005. The small orbit the Sun between 0.08 and 0.18 white circle in the central occulting disk represents the size a.u. As seen from Earth, this zone There may be plenty of of the Sun. SoHo / LASCo ConSortium (Nasa / ESA) extends as far as 10.5° from the center Vulcanoids out there, but of the solar disk. Studies by Daniel D. how can they be discov- ered? A CCD camera coupled to a Determine the faintest star you can telescope is clearly essential. As many record at or near the zenith. If you CCD users know, it’s possible to re- can capture stars fainter than 8th cord fairly faint stars even near a full magnitude, then your setup has what Moon at night, and the sky during a it takes to hunt for Vulcanoids. total solar eclipse has a similar bright- You will greatly improve your Stable ness. Here are a few things to con- ability to image faint Vulcanoids Vulcanoid zone sider that might help increase your by preventing wavelengths that are chance of success. shorter than orange from reaching If you plan to do the search during your camera. Vulcanoids are likely a total solar eclipse, test your tele- to be Mercury-like in color, greatly Merc ry u scope setup on the zenith weeks or favoring the red and near infrared (IR) months before you head off to your colors. By filtering out the blue of Venus observing site. You can simulate the the sky background (from O2 Rayleigh typical range of sky conditions at scattering), the green of the corona Earth totality by taking CCD exposures of (e.g., Iron emission lines), and the yel- a cloudless, moonless sky at dusk or low from Sun (scattered into the sky The dynamically stable Vulcanoid zone extends dawn. Capture images of the zenith from outside the lunar shadow), you 0.08 to 0.18 astronomical unit (12 to 27 million when the Sun’s center is between will significantly reduce background kilometers) from the Sun. 4.25° and 5.25° below the ideal ho- noise without sacrificing the bright- ECLIPSE 2009 27 Searching for Vulcanoids Search area Sun Search area 4ϒ ness of potential Vulcanoids. Recent ute prior to totality. E c l i p t i c Vulcanoid hunters have used OG Use these coordinates 590 (090) and RG 630 (091) Wratten to help align your filters to image stars as faint as +13.5 camera mount and to 8ϒ magnitude during the 2008 August 1 locate your Vulcanoid 10.5ϒ eclipse. observation point. Another technique that holds great Even experienced promise is to use cameras that are eclipse chasers often sensitive to both visual and near IR get so caught up in the frenzy and This diagram (drawn to scale) shows the prime wavelengths. The surface tempera- emotion at the onset of totality that Vulcanoid search area during totality. To reduce ture of objects residing within the carefully laid plans become chaotic. glare from the corona, aim your CCD-equipped stable Vulcanoid zone could be as So prior to the eclipse, practice set- telescope at least 2.5° from the Sun’s center. high as 825°C (1517°F) due to their ting up, alignment, and acquiring close proximity to the Sun. Such your Vulcanoid search coordinate circular orbit around the Sun would objects are expected to be strong ra- during the daytime. Practice it until complete one revolution in 8.26 to diators in the IR portion of the spec- you become very familiar being able 27.9 days. Thus, in a pair of short trum. SLR cameras made sensitive to to setup in a reasonable amount of exposures, say, 4 minutes apart, the the near IR, such as those modified time. Bring enough spare parts and asteroid would move as much as 0.5 by MaxMax (www.maxmax.com), of- batteries just in case. Create and use arcminute on the sky. fer a relatively inexpensive near IR a checklist that even includes the A far better strategy is for a pair detector solution while avoiding the obvious. More than one person has of observers working in tandem to cooling and thermal shield problems forgotten to remove a lens cap at the position themselves in different coun- associated with chilled mid and far IR right time! tries along the eclipse path.
Recommended publications
  • The Orbital Distribution of Near-Earth Objects Inside Earth’S Orbit
    Icarus 217 (2012) 355–366 Contents lists available at SciVerse ScienceDirect Icarus journal homepage: www.elsevier.com/locate/icarus The orbital distribution of Near-Earth Objects inside Earth’s orbit ⇑ Sarah Greenstreet a, , Henry Ngo a,b, Brett Gladman a a Department of Physics & Astronomy, 6224 Agricultural Road, University of British Columbia, Vancouver, British Columbia, Canada b Department of Physics, Engineering Physics, and Astronomy, 99 University Avenue, Queen’s University, Kingston, Ontario, Canada article info abstract Article history: Canada’s Near-Earth Object Surveillance Satellite (NEOSSat), set to launch in early 2012, will search for Received 17 August 2011 and track Near-Earth Objects (NEOs), tuning its search to best detect objects with a < 1.0 AU. In order Revised 8 November 2011 to construct an optimal pointing strategy for NEOSSat, we needed more detailed information in the Accepted 9 November 2011 a < 1.0 AU region than the best current model (Bottke, W.F., Morbidelli, A., Jedicke, R., Petit, J.M., Levison, Available online 28 November 2011 H.F., Michel, P., Metcalfe, T.S. [2002]. Icarus 156, 399–433) provides. We present here the NEOSSat-1.0 NEO orbital distribution model with larger statistics that permit finer resolution and less uncertainty, Keywords: especially in the a < 1.0 AU region. We find that Amors = 30.1 ± 0.8%, Apollos = 63.3 ± 0.4%, Atens = Near-Earth Objects 5.0 ± 0.3%, Atiras (0.718 < Q < 0.983 AU) = 1.38 ± 0.04%, and Vatiras (0.307 < Q < 0.718 AU) = 0.22 ± 0.03% Celestial mechanics Impact processes of the steady-state NEO population.
    [Show full text]
  • The Minor Planets
    The Minor Planets Swinburne Astronomy Online 3D PDF c SAO 2012 The Minor Planets c Swinburne Astronomy Online 2012 1 Description 1.1 Minor planets Our view of the Solar System has changed dramatically over the past 15 years with the discovery of new classes of small bodies. Mi- nor planets are another name for asteroids, or celestial bodies that orbit the Sun that are not otherwise classed as planets or comets. Generally, minor planets are relatively small rocky bodies, while comets are icy bodies that become active when their orbits carry them close to the Sun. (An \active" comet exhibits a large coma and a long tail.) The minor planets can be classified by their orbital characteristics. In this 3D PDF, we have included 5 classes of minor planets: (1) the Near Earth Asteroids (NEAs), (2) the main belt asteroids, (3) the Trojan asteroids of Jupiter, (4) the Centaurs, and (5) the Trans-Neptunian Objects (TNOs). The dataset used comes from the Minor Planets Centre. As of 19 November 2012, there were 9,346 NEAs (comprising 732 Atens, 4686 Apollos and 3928 Amors); 581,613 main belt asteroids; 5,407 jovian Trojans; 330 Centaurs; and 1,150 TNOs. (Note than in this 3D PDF, we have only included 11,678 main belt asteroids.) • The Near Earth Asteroids have perihelion distances of less than 1.3 AU, and include the following sub-classes: { Atens have aphelion distances greater than 0.983 AU, and semi-major axes less than 1 AU { Apollos have perihelion distances less than 1.017 AU, and semi-major axes greater than 1 AU { Amors have perihelion distances between 1.017 and 1.3 AU and semi-major axes greater than 1 AU • The main belt asteroids reside between the orbits of Mars and Jupiter, with most of the asteroids orbiting between about 2.1 AU and 3.3 AU.
    [Show full text]
  • Planetary Science from a Next-Gen Suborbital Platform: Sleuthing the Long Sought After Vulcanoid Aster- Oids
    Next-Generation Suborbital Researchers Conference (2010) (2010) 4004.pdf Planetary Science from a Next-Gen Suborbital Platform: Sleuthing the Long Sought After Vulcanoid Aster- oids. S.A. Stern1 , D.D. Durda1, M. Davis1, and C.B. Olkin1. Southwest Research Institute, Suite 300, 1050 Walnut Street, Boulder, CO 80302, [email protected]. Introduction: We are on the verge of a revolution in pheric haze and turbulence are among the daunting scientific access to space. This revolution, fueled by challenges faced by ground-based observers searching billionaire investors like Richard Branson and Jeff for objects near the Sun at twilight. Consequently, only Bezos, is fielding no less than three human flight sub- a few visible-wavelength ground-based searches for orbital systems in the coming 24 months. This new Vulcanoids have been conducted. stable of vehicles, originally intended to open up a Experiment: We will conduct a large area search space tourism market, includes Virgin Galactic’s for Vulcanoids using our SWUIS imager developed for SpacesShip2, Blue Origin’s New Shepard, and Space Shuttle and high altitude F-18 flights. We will XCOR’s Lynx. Each offers the capability to fly multi- conduct our Vulcanoid search experiment at altitudes ple humans to altitudes of 70-140 km on a frequent of 100-140 km near twilight so that the Vulcanoid re- (daily to weekly) basis for per-seat launch costs of gion is seen above a dark Earth with the Sun below the $100K-$200K/launch. The total investment in these depressed horizon. In this way we will eliminate the systems is now approaching $1B, and test flights of scattered light problems that have dogged all ground- each are set to begin in 2010.
    [Show full text]
  • 1950 Da, 205, 269 1979 Va, 230 1991 Ry16, 183 1992 Kd, 61 1992
    Cambridge University Press 978-1-107-09684-4 — Asteroids Thomas H. Burbine Index More Information 356 Index 1950 DA, 205, 269 single scattering, 142, 143, 144, 145 1979 VA, 230 visual Bond, 7 1991 RY16, 183 visual geometric, 7, 27, 28, 163, 185, 189, 190, 1992 KD, 61 191, 192, 192, 253 1992 QB1, 233, 234 Alexandra, 59 1993 FW, 234 altitude, 49 1994 JR1, 239, 275 Alvarez, Luis, 258 1999 JU3, 61 Alvarez, Walter, 258 1999 RL95, 183 amino acid, 81 1999 RQ36, 61 ammonia, 223, 301 2000 DP107, 274, 304 amoeboid olivine aggregate, 83 2000 GD65, 205 Amor, 251 2001 QR322, 232 Amor group, 251 2003 EH1, 107 Anacostia, 179 2007 PA8, 207 Anand, Viswanathan, 62 2008 TC3, 264, 265 Angelina, 175 2010 JL88, 205 angrite, 87, 101, 110, 126, 168 2010 TK7, 231 Annefrank, 274, 275, 289 2011 QF99, 232 Antarctic Search for Meteorites (ANSMET), 71 2012 DA14, 108 Antarctica, 69–71 2012 VP113, 233, 244 aphelion, 30, 251 2013 TX68, 64 APL, 275, 292 2014 AA, 264, 265 Apohele group, 251 2014 RC, 205 Apollo, 179, 180, 251 Apollo group, 230, 251 absorption band, 135–6, 137–40, 145–50, Apollo mission, 129, 262, 299 163, 184 Apophis, 20, 269, 270 acapulcoite/ lodranite, 87, 90, 103, 110, 168, 285 Aquitania, 179 Achilles, 232 Arecibo Observatory, 206 achondrite, 84, 86, 116, 187 Aristarchus, 29 primitive, 84, 86, 103–4, 287 Asporina, 177 Adamcarolla, 62 asteroid chronology function, 262 Adeona family, 198 Asteroid Zoo, 54 Aeternitas, 177 Astraea, 53 Agnia family, 170, 198 Astronautica, 61 AKARI satellite, 192 Aten, 251 alabandite, 76, 101 Aten group, 251 Alauda family, 198 Atira, 251 albedo, 7, 21, 27, 185–6 Atira group, 251 Bond, 7, 8, 9, 28, 189 atmosphere, 1, 3, 8, 43, 66, 68, 265 geometric, 7 A- type, 163, 165, 167, 169, 170, 177–8, 192 356 © in this web service Cambridge University Press www.cambridge.org Cambridge University Press 978-1-107-09684-4 — Asteroids Thomas H.
    [Show full text]
  • Ice Ontnos: Focus on 136108 Haumea
    Ice onTNOs: Focus on 136108 Haumea C. Dumas Collaborators: A. Alvarez, A. Barucci, C. deBergh, B. Carry, A. Guilbert, D. Hestroffer, P. Lacerda, F. deMeo, F. Merlin, C. Snodgrass, P. Vernazza, … Haumea Pluto (dwarf planets) DistribuTon of TNOs Largest TNOs Icy bodies in the OPSII context • Reservoir of volales in the solar system (H2O, N2, CH4, CO, CO2, C2H6, NH3OH, etc) • Small bodies populaon more hydrated than originally pictured – Main-belt comets (Hsieh and JewiZ 2006) – Themis asteroids family (Campins et al. 2010, Rivkin and Emery 2010) • Transport of water to the inner terrestrial planets (e.g. talk by Paul Hartogh) Paranal Observatory 6 SINFONI at UT4 7 SINFONI + NACO at UT4 8 SINFONI = MACAO + SPIFFI (SINFONI=Spectrograph for INtegral Field Observations in the Near Infrared) • AO SYSTEM: MACAO (Multi-Application Curvature Adaptive Optics): – Similar to UTs AO system for VLTI – 60 elements curvature sensing bimorph mirror – NGS or LGS – Developed by ESO • NEAR-IR SPECTRO: SPIFFI (SPectrometer for Infrared Faint Field Imaging): – 3-D spectrograph, 32 image slices, 1-2.5µm – Developed by MPE:Max Planck Institute for Extraterrestrial Physics + NOVA: Netherlands Research School for Astronomy SINFONI - Main characteristics • Location UT4 Cassegrain • Wavelength range 1-2.5µm • Detector 2048 x 2048 HAWAII array • Gratings J,H,K,H+K • Spectral resolution 1500 (H+K-filter) to 4000 (K-band) (outside OH lines) • Limiting magnitude (0.1”/spaxel) K~18.2, H+K~19.2 in hr, SNR~10 • FoV sampling 32 slices • Spatial resolution 0.25”/slice (no-AO), 0.1”(AO), 0.025” (AO) • Resulting FoV 8”x8”, 3”x3”, 0.8”x0.8” • Modes noAO, NGS-AO, LGS-AO SINFONI - IFS Principles SINFONI - IFS Principles (Cont’d) SINFONI - products Reconstructed image PSF spectrum H+K TNOs spectroscopy Orcus (Carry et al.
    [Show full text]
  • Colours of Minor Bodies in the Outer Solar System II - a Statistical Analysis, Revisited
    Astronomy & Astrophysics manuscript no. MBOSS2 c ESO 2012 April 26, 2012 Colours of Minor Bodies in the Outer Solar System II - A Statistical Analysis, Revisited O. R. Hainaut1, H. Boehnhardt2, and S. Protopapa3 1 European Southern Observatory (ESO), Karl Schwarzschild Straße, 85 748 Garching bei M¨unchen, Germany e-mail: [email protected] 2 Max-Planck-Institut f¨ur Sonnensystemforschung, Max-Planck Straße 2, 37 191 Katlenburg- Lindau, Germany 3 Department of Astronomy, University of Maryland, College Park, MD 20 742-2421, USA Received —; accepted — ABSTRACT We present an update of the visible and near-infrared colour database of Minor Bodies in the outer Solar System (MBOSSes), now including over 2000 measurement epochs of 555 objects, extracted from 100 articles. The list is fairly complete as of December 2011. The database is now large enough that dataset with a high dispersion can be safely identified and rejected from the analysis. The method used is safe for individual outliers. Most of the rejected papers were from the early days of MBOSS photometry. The individual measurements were combined so not to include possible rotational artefacts. The spectral gradient over the visible range is derived from the colours, as well as the R absolute magnitude M(1, 1). The average colours, absolute magnitude, spectral gradient are listed for each object, as well as their physico-dynamical classes using a classification adapted from Gladman et al., 2008. Colour-colour diagrams, histograms and various other plots are presented to illustrate and in- vestigate class characteristics and trends with other parameters, whose significance are evaluated using standard statistical tests.
    [Show full text]
  • 11000 Scientists Around the World Have the Final Say on What's a Planet
    International Astronomical Union (IAU) members vote on a new planet definition during a meeting in Prague Aug. 24, 2006. The vote redefined Pluto as a dwarf planet. MICHAL CIZEK/AFP/GETTY IMAGES DEFINITION: PLANET 11,000 scientists around the world have the final say on what’s a planet — or not By Mary Helen Berg a planet is a planet or just an orbiting ice of planetary scientists, academics and ball. Right now, the worlds that make historians support research, confirm HE NUMBER OF PLANETS IN OUR the cut are Mercury, Venus, Earth, Mars, celestial discoveries, document and solar system is … well, it depends Jupiter, Saturn, Uranus and Neptune. preserve data and even track potentially on who you ask. Pluto fans, sporting The IAU is “responsible for managing the dangerous asteroids. T-shirts that read “Never Forget,” astronomical world,” said Gareth Williams, Tstill say there are nine. Meanwhile, some associate director of the NASA-funded IAU PLUTO OUT astronomers say the tally should be 13. But Minor Planet Center (MPC). “They define Most of these working groups fly under the arbiter on all things astronomical, the everything that astronomers need to talk the radar. But in 2006, one committee International Astronomical Union (IAU), about objects in a consistent way. So, if I’m found itself under global scrutiny when, for recognizes only eight planets. talking about an object at a certain point the first time, the astronomy community As the world’s largest professional in the sky, some other astronomer knows demanded an official definition of “planet.” organization for astronomers, the IAU exactly what I am talking about.” The seven-member Planet Definition represents 11,000 scientists from 95 In other words, the IAU controls cosmic countries and has the final say on whether chaos on Earth.
    [Show full text]
  • Ceres and Pluto: Dwarf Planets As a New Way of Thinking About an Old Solar System
    Ceres and Pluto: Dwarf Planets as a New Way of Thinking about an Old Solar System TEACHER GUIDE BACKGROUND The decision by the International Astronomical Union (IAU) in 2006 to define the terms “planet” and “dwarf planet” has caught the attention of the public and students from grade school to graduate school. The IAU’s decision has not changed the structure of the solar system; it has merely presented a different way of classifying the bodies that make it up. Planets are the Greek word for “wanderers” that were known as lights that moved in the sky. This middle school activity, developed for NASA’s Dawn mission, utilizes a researched-based instructional strategy called direct vocabulary instruction to help students understand the new definitions of planet and dwarf planet. Many of us have grown up with an understanding that our solar system is comprised of remnants from its early formation 4.5 billion years ago, primarily: bodies such as the Sun, planets, asteroids and comets; gas and dust, as well as a large volume of space. Many school children have learned the names and locations of the planets relative to the Sun using a mnemonic such as My Very Exceptional Mother Just Sat Upon Nine Porcupines (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto). The last of these bodies to be discovered, Pluto, has recently been reclassified as a dwarf planet. Pluto’s reduced status has even resulted in a new term as we enter 2007: someone or something has been “Plutoed” if that person or thing has been downsized in its prominence.
    [Show full text]
  • Planets of Our Solar System - Iwan P
    ASTRONOMY AND ASTROPHYSICS - Planets Of Our Solar System - Iwan P. Williams PLANETS OF OUR SOLAR SYSTEM Iwan P. Williams Astronomy Unit, Queen Mary University of London, London UK Keywords: Solar System, Small Bodies, Planets, Dwarf Planets, Satellites, Trans- Neptunian Objects, Asteroids, Plutoids Contents 1. Introduction 2. The Copernican Revolution 3. New telescopes - New discoveries 3.1. The Titius-Bode Law 3.2. The Discovery of Uranus 3.3. Four New Planets 3.4. The Discovery of Neptune 3.5. The Asteroid Belt is discovered 3.6. The Discovery of Pluto 3.7. The True Size of Pluto 4. Trans Neptunian Objects 4.1. The Edgeworth-Kuiper Belt is discovered 5. Planets and Dwarf PLanets 6. The larger members of the Solar System 6.1. Mercury 6.2. Venus 6.3. Earth 6.4. The Moon 6.5. Mars 6.6. Ceres 6.7. Jupiter 6.8. Io 6.9. Europa 6.10. Ganymede 6.11. CallistoUNESCO – EOLSS 6.12. Saturn 6.13. Titan 6.14. Uranus 6.15. Neptune SAMPLE CHAPTERS 6.16. Triton 6.17. Pluto 6.18. Haumea 6.19. Makemake 6.20. Eris 6.21. Other Large Bodies 7. Extra-solar Planets 8. Conclusions Glossary ©Encyclopedia of Life Support Systems (EOLSS) ASTRONOMY AND ASTROPHYSICS - Planets Of Our Solar System - Iwan P. Williams Bibliography Biographical Sketch Summary When humans noticed that most stars appeared to stay in fixed pattern in the sky, they realized that a few moved against this background. They called these wandering stars, or planets. Over the centuries, our knowledge of these has vastly increased and, in the process, our understanding of the system as a whole has changed.
    [Show full text]
  • In Order to Decide Whether You Like a Particular Soup, Do You
    In order to decide whether you like a particular soup, do you need to eat the whole pot? Usually, you can get a good sense of the flavor of the soup by taking a small taste, or a sample. When conducting a study, it is usually not possible to survey every person or object in the population in which you are interested (for example, all the residents of the United States, all the students at your school, or all teenage shoppers). However, just as you can learn about the flavor of a soup with a small taste instead of eating the whole pot, you can learn about a population by sampling instead of taking a census. Unfortunately, large groups of people are much harder to stir than pots of soup to get a representative mix of their populations. In this lesson, you will consider ways that statisticians do the equivalent of “stirring” populations in order to take samples that represent the whole population well. As you work with your team today, consider the following questions. How should we decide what is “typical” of a group? How do random selection and intentional selection compare? 9-16. How should you choose people for your survey to make up a sample that you think represents the population for your research question? a. Discuss this question with your team and write down your ideas. Be sure to justify why your ideas will help you choose a representative sample. b. Do you think your sampling method is better than randomly selecting members of the population? Why or why not? 9-17.
    [Show full text]
  • Physical Properties of Kuiper Belt and Centaur Objects: Constraints from the Spitzer Space Telescope
    Stansberry et al.: Physical Properties 161 Physical Properties of Kuiper Belt and Centaur Objects: Constraints from the Spitzer Space Telescope John Stansberry University of Arizona Will Grundy Lowell Observatory Mike Brown California Institute of Technology Dale Cruikshank NASA Ames Research Center John Spencer Southwest Research Institute David Trilling University of Arizona Jean-Luc Margot Cornell University Detecting heat from minor planets in the outer solar system is challenging, yet it is the most efficient means for constraining the albedos and sizes of Kuiper belt objects (KBOs) and their progeny, the Centaur objects. These physical parameters are critical, e.g., for interpreting spec- troscopic data, deriving densities from the masses of binary systems, and predicting occultation tracks. Here we summarize Spitzer Space Telescope observations of 47 KBOs and Centaurs at wavelengths near 24 and 70 µm. We interpret the measurements using a variation of the stan- dard thermal model (STM) to derive the physical properties (albedo and diameter) of the targets. We also summarize the results of other efforts to measure the albedos and sizes of KBOs and Centaurs. The three or four largest KBOs appear to constitute a distinct class in terms of their albedos. From our Spitzer results, we find that the geometric albedo of KBOs and Centaurs is correlated with perihelion distance (darker objects having smaller perihelia), and that the albe- dos of KBOs (but not Centaurs) are correlated with size (larger KBOs having higher albedos). We also find hints that albedo may be correlated with visible color (for Centaurs). Interest- ingly, if the color correlation is real, redder Centaurs appear to have higher albedos.
    [Show full text]
  • Near-Earth Asteroid Search Programs 45
    Stokes et al.: Near-Earth Asteroid Search Programs 45 Near-Earth Asteroid Search Programs Grant H. Stokes and Jenifer B. Evans Massachusetts Institute of Technology Lincoln Laboratory Stephen M. Larson University of Arizona The discovery of the potentially hazardous near-Earth asteroid (NEA) component of the minor-planet population has been enhanced by better detecting and computing technology. A government mandate to quantify the terrestrial impact hazard and to detect 90% of all NEAs larger than 1 km can be realistically addressed. The characteristics, capabilities, and strategies of the major search programs illustrate the challenges and solutions toward meeting the Spaceguard goal. This chapter reviews the historical context of early asteroid detection and of the current and anticipated search programs. It describes the search systems and discusses challenges in maximizing the NEA detection rate. 1. INTRODUCTION AND BACKGROUND the first few hundred asteroids, to film-based observations in the 1890s. The first asteroid discovered by photography, The past decade has witnessed an explosion in the num- (323) Brucia, was discovered by Max Wolf in 1891. The ber of cataloged asteroids. Of the more than 35,000 num- most common photographic-based search methods were bered asteroids discovered in the last 200 years, 62% of either (1) to take a single long exposure and visually inspect these were found in the past decade. Similarly, of the 1785 the plate or film for trails as the asteroid moved during the NEAs that are now known, 89% have been discovered in exposure, or (2) to take two successive exposures and visu- the past 10 years.
    [Show full text]