Distribution by Scientific Domains

Kinds of Planets

  • extrasolar planet
  • giant planet
  • terrestrial planet
  • transiting planet

  • Terms modified by Planets

  • planet earth
  • planet formation

  • Selected Abstracts

    Saving the Planet in the Pacific Northwest

    W. Gregory Hood
    No abstract is available for this article. [source]

    Valuing the Planet: The Role of Economics in the Climate Crisis

    David DeRemer Senior Strategist
    First page of article [source]

    Planet of Slums by Mike Davis

    R. Alan Walks
    No abstract is available for this article. [source]

    Fire Planet, Fire Creature

    Stephen Pyne

    Pandemics and the Planet of Slums

    No abstract is available for this article. [source]

    An Introduction to Our Dynamic Planet , By Stephen Blake, Kevin Burton, Nigel Harris, Ian Parkinson, Nick Rogers and Mike Widdowson

    Laurence Hopkinson
    No abstract is available for this article. [source]

    Cartoons from Another Planet: Japanese Animation as Cross-Cultural Communication

    Shinobu Price
    First page of article [source]

    Books and Multimedia Reviews

    Article first published online: 4 FEB 2010
    Book reviewed in this article: Catalogue of Meteorites, Fifth Edition (Revised and Enlarged) by Monica M. Grady Extrasolar Planets: The Search for New Worlds by Stuart Clark The Moon: Resources, Future Development and Colonization by David Schrunk, Burton Sharpe, Bonnie Cooper and Madhu Thangavelu Rare Earth: Why Complex Life is Uncommon in the Universe by Peter D. Ward and Donald E. Brownlee [source]

    Strategies in Human Nonmonotonic Reasoning

    Marilyn Ford
    Although humans seem adept at drawing nonmonotonic conclusions, the nonmonotonic reasoning systems that researchers develop are complex and do not function with such ease. This paper explores people's reasoning processes in nonmonotonic problems. To avoid the problem of people's conclusions being based on knowledge rather than on some reasoning process, we developed a scenario about life on another planet. Problems were chosen to allow the systematic study of people's understanding of strict and nonstrict rules and their interactions. We found that people had great difficulty reasoning and we identified a number of negative factors influencing their reasoning. We also identified three positive factors which, if used consistently, would yield rational and coherent reasoning,but no subject achieved total consistency. (Another possible positive factor, specificity, was considered but we found no evidence for its use.) It is concluded that nonmonotonic reasoning is hard. When people need to reason in a domain where they have no preconceived ideas, the foundation for their reasoning is neither coherent nor rational. They do not use a nonmonotonic reasoning system that would work regardless of content. Thus, nonmonotonic reasoning systems that researchers develop are expected to do more reasoning than humans actually do! [source]

    The Great American Biotic Interchange revisited

    ECOGRAPHY, Issue 2 2010
    Sarah Cody
    The "Great American Biotic Interchange" (GABI) is regarded as a defining event in the biogeography of the Americas. It is hypothesized to have occurred when the Isthmus of Panama closed ca three million years ago (Ma), ending the isolation of South America and permitting the mixing of its biota with that of North America. This view of the GABI is based largely upon the animal fossil record, but recent molecular biogeographic studies of plants that show repeated instances of long-distance dispersal over major oceanic barriers suggest that perhaps the land bridge provided by the isthmus may have been less necessary for plant migration. Here we show that plants have significantly earlier divergence time estimates than animals for historical migration events across the Isthmus of Panama region. This difference in timing indicates that plants had a greater propensity for dispersal over the isthmus before its closure compared with animals. The GABI was therefore asynchronous for plants and animals, which has fundamental implications for the historical assembly of tropical biomes in the most species-rich forests on the planet. [source]

    Something ,Paralogical' Under the Sun: Lyotard's Postmodern Condition and science education

    Michalinos ZembylasArticle first published online: 2 NOV 200
    Sometimes I dream that I am an astronaut. I land my spaceship on a distant planet. When I tell me children on that planet that on earth school is compulsory and that we have homework every evening, they split their sides laughing. And so I decide to stay with them for a long, long time, Well anyway, until the summer holidays. (Cited in Lyotard, 1995, p. xix) Each state of the mind is irreducible. The mere act of giving it a name, that is of classifying it, implies a falsification of it. From all this, it would be possible to deduce that there is no science in Tlon, let alone rational thought. The paradox, however, is that sciences exist, in countless number, The metaphysicians of Tlon are not looking for truth, nor even for an approximation of it; they are after a kind of amazement. They consider metaphysics a branch of fantastic literature. They know that a system is nothing more than the subordination of all aspects of the universe to some one of them. Even the phrase ,all the aspects' can be rejected, since it presupposes the impossible inclusion of the present moment, and of past moments. (Borges, 1962, p. 10) [source]

    Simultaneous Quantitative Determination of Cadmium, Lead, and Copper on Carbon-Ink Screen-Printed Electrodes by Differential Pulse Anodic Stripping Voltammetry and Partial Least Squares Regression

    ELECTROANALYSIS, Issue 23 2008
    Michael Cauchi
    Abstract Water is a vital commodity for every living entity on the planet. However, water resources are threatened by various sources of contamination from pesticides, hydrocarbons and heavy metals. This has resulted in the development of concepts and technologies to create a basis for provision of safe and high quality drinking water. This paper focuses on the simultaneous quantitative determination of three common contaminants, the heavy metals cadmium, lead and copper. Multivariate calibration was applied to voltammograms acquired on in-house printed carbon-ink screen-printed electrodes by the highly sensitive electrochemical method of differential pulse anodic stripping voltammetry (DPASV). The statistically inspired modification of partial least squares (SIMPLS) algorithm was employed to effect the multivariate calibration. The application of data pretreatment techniques involving range-scaling, mean-centering, weighting of variables and the effects of peak realignment are also investigated. It was found that peak realignment in conjunction with weighting and SIMPLS led to the better overall root mean square error of prediction (RMSEP) value. This work represents significant progress in the development of multivariate calibration tools in conjunction with analytical techniques for water quality determination. It is the first time that multivariate calibration has been performed on DPASV voltammograms acquired on carbon-ink screen-printed electrodes. [source]

    Agriculture Under the Public Eye: Who Cares for What

    EUROCHOICES, Issue 2 2004
    Cees Veerman
    Summary Agriculture Under the Public Eye: Who Cares for What? The new CAP is becoming geared towards a more sustainable agriculture that takes account of the needs of future generations. Achieving sustainability, however, means meeting three challenges-, (a) profit - strengthening the viability and competitiveness of the agricultural sector; (b) planet - the ecological challenge of promoting good environmental practices; and (c) people-the social challenge to improve the living conditions and economic opportunities in rural areas. In the food chain we see responses to consumer concerns about food safety, quality and welfare issues through the development and implementation of mandatory and voluntary quality control and assurance schemes. And the consolidation and internationalisation of the food retailing and the manufacturing industry is expected to continue. An important duality has emerged. On the one side, we find a state system of regulation, on the other a system of self-regulation, largely driven by the major forces in supply chain management, the food retailers in particular. A simple and effective regulatory environment for the agri-food complex is essential if we are to achieve our competitiveness goals. One of the priorities for discussion by politicians, therefore, should be whether current and expected policy and industry developments should lead to a review of the balance between markets and government, ,who cares for what?' l'agriculture aux yeux des politiques publiques qui doit faire quoi? La nouvelle PAC est maintenant bien orientée vers une agriculture plus durable, en mesure de tenir compte des besoins des générations futures. Une véritable durabilityé suppose cependant que soient relevés trois défis: a) le profit - renforcer la viabilityé et la compétitivité du secteur agricole; b) la planète - le défiécologique de promouvoir des pratiques favorables à l'environnement; c) les gens - le défi social d'améliorer les conditions de vie et les opportunités économiques dans les zones rurales. Du côté des filières alimentaires, la réponse à trouver aux inquiétudes des consommateurs vis à vis de la qualityé sanitaire et organoleptique des produits devrait pouvoir venir de l'élaboration de contrôles de qualityé et de systèmes d'assurances, à appliquer sur la base du volontariat ou à rendre obligatoires. En même temps, il faut s'attendre à la continuation du mouvement vers l'affermissement du rôle des industries alimentaires et du commerce de détail, ainsi qu'à leur internationalisation. Un système dual vient d'émerger: d'un côté, un système de réglementations étatiques, de l'autre, une autodiscipline, pilotée par les plus solides des maillons de la filière, en particulier les grandes surfaces. Un environnement réglementaire à la fois simple et efficace est essentiel pour atteindre l'objectif de compétitivité du complexe agroalimentaire, II en résulte que, pour les pouvoirs publics, une des grandes questions à discuter est de savoir dans quelle mesure l' évolution des conditions politiques et celle du développement industriel imposent une révision de l'équilibre actuel entre les marchés et les autorités gouvernementales; en d'autres termes, qui doit faire quoi ? Landwirtschaft in der öffentlichen Meinung; Wer ist wofür zuständig? Die neue GAP wird gerade auf eine nachhaltigere Landwirtschaft hin ausgerichtet, welche die Bedürfnisse der kommenden Generationen berücksichtigt. Nachhaltigkeit kann jedoch nur erzielt werden, wenn den folgenden drei Herausforderungen Rechnung getragen wird: (a) Ökonomie , Stärkung der Leistungs- und Wettbewerbsfähigkeit des Landwirtschaftssektors; (b) Ökologie , Förderung umweltgerechter Verfahrensweisen; und (c) Soziales - Verbesserung der Lebensbedingungen und der wirtschaftlichen Lage im ländlichen Raum. Im Bereich der Nahrungsmittelkette wird den Bedenken der Verbraucher hinsichtlich der Nahrun gsmittelsicherheit, der Qualität und der Wohlfahrt durch die Entwicklung und Implementierung von obligatorischen und freiwilligen Qualitätskontrollen und Sicherheitsprogrammen Rechnung getragen. Es ist davon auszugehen, dass sich die Konsolidierung und Lnternationalisierung im Bereich des Lebensmitteleinzel-handels und der weiterverarbeitenden Industrie fortsetzen wird. Es ist eine bedeutsame Dualität entstanden. Auf der einen Seite erfolgt eine Regulierung seitens des Staates, auf der anderen Seite erfolgt eine Selbstregulierung durch die Vermarktungskette, insbesondere durch den Lebensmitteleinzelhandel. Eine sowohl einfache als auch wirksame Regulierung der Agrar- und Ernährungswirtschaft ist von grundlegender Bedeutung für das Erreichen unserer Wettbewerbsziele. Daher sollte in der Politik mit Priorität diskutiert werden, ob die gegenwärtige und zukünftige Politik und auch die industrielle Entwicklung zu einem neuen Gleichgewicht zwischen Markt und Staatseingriffen führen sollte: Wer ist wofür zuständig? [source]

    On Hating to Hate

    FAMILY PROCESS, Issue 3 2006
    Hate may be the most dangerous of all emotions for the survival of the planet. The author addresses two questions: What obscures hate when it is actually present? and What masquerades as hate but isn't? Using illustrations from a wide range of fields, the author contends that discerning hate is both essential and far trickier than we think. She concludes by asserting that overcoming hate requires imagination. We must learn to imagine a world without hate and unimagine a world with hate. [source]

    Effects of an exotic invasive macrophyte (tropical signalgrass) on native plant community composition, species richness and functional diversity

    FRESHWATER BIOLOGY, Issue 6 2010
    Summary 1.,The issue of freshwater species being threatened by invasion has become central in conservation biology because inland waters exhibit the highest species richness per unit area, but apparently have the highest extinctions rates on the planet. 2.,In this article, we evaluated the effects of an exotic, invasive aquatic grass (Urochloa subquadripara, tropical signalgrass) on the diversity and assemblage composition of native macrophytes in four Neotropical water bodies (two reservoirs and two lakes). Species cover was assessed in quadrats, and plant biomass was measured in further quadrats, located in sites where tropical signalgrass dominated (D quadrats) and sites where it was not dominant or entirely absent (ND quadrats). The effects of tropical signalgrass on macrophyte species richness, Shannon diversity and number of macrophyte life forms (a surrogate of functional richness) were assessed through regressions, and composition was assessed with a DCA. The effects of tropical signalgrass biomass on the likelihood of occurrence of specific macrophyte life forms were assessed through logistic regression. 3.,Tropical signalgrass had a negative effect on macrophyte richness and Shannon and functional diversity, and also influenced assemblage composition. Emergent, rooted with floating stems and rooted submersed species were negatively affected by tropical signalgrass, while the occurrence of free-floating species was positively affected. 4.,Our results suggest that competition with emergent species and reduction of underwater radiation, which reduces the number of submersed species, counteract facilitation of free-floating species, contributing to a decrease in plant diversity. In addition, homogenisation of plant assemblages shows that tropical signalgrass reduces the beta diversity in the macrophyte community. 5.,Although our results were obtained at fine spatial scales, they are cause for concern because macrophytes are an important part of freshwater diversity. [source]

    When Land Was Cheap, and Labor Dear: James Madison's ,Address to the Albemarle Agricultural Society' and the Problem of Southern Agricultural Reform

    Lynn A. Nelson
    James Madison's 1818 Address to the Albemarle Agricultural Society offers new insight into the diverse historiography of agricultural reform in the American South. Madison described a planet with limited resources, accused Virginia farmers of wasting what little they had, and offered suggestions for ways to intensify cultivation. Many scholars have analyzed the southern agricultural reform crusade, but differ widely on whether it was successful, and the reasons why. Madison tried to balance high farming with southern independence. Southern farming could not imitate modern agriculture from England and the Northeastern states because of the region's ecological distinctiveness. Madison was reluctant to risk tested adaptations by importing to crops, animals, and fertilizers. Southern farmers reflected his ecological conservatism, and the movement for reform stalled. [source]

    Apocalyptic anti-urbanism: Mike Davis and his planet of slums

    Tom Angotti
    First page of article [source]

    Role of the zoo veterinarian in the conservation of captive and free-ranging wildlife

    S. L. DEEM
    The challenges to execute wildlife conservation projects successfully have become more complex as anthropogenic changes continue to stress the planet, changing wild lands. As the wild becomes less so, more species are placed in captivity to improve their chances of long-term survival, while concurrently management (and medicine) for free-ranging wildlife has become increasingly important. A variety of disciplines, including veterinary medicine, is now recognized as key to wildlife conservation. Although veterinarians have been involved in conservation for decades, it is only recently that their role has become more appreciated in the larger conservation community. This realization of the contributions of veterinarians has occurred at a time when disease has been recognized as significantly impacting species' conservation both in situ and ex situ. Today, veterinarians work with captive and free-ranging animals to prevent and/or treat diseases that threaten species' survival. Most of these diseases are associated with the increasing human footprint. In this paper, I present wildlife health in today's world and the zoo veterinarian's role in wildlife conservation. [source]

    Rainfall effects on rare annual plants

    JOURNAL OF ECOLOGY, Issue 4 2008
    Jonathan M. Levine
    Summary 1Variation in climate is predicted to increase over much of the planet this century. Forecasting species persistence with climate change thus requires understanding of how populations respond to climate variability, and the mechanisms underlying this response. Variable rainfall is well known to drive fluctuations in annual plant populations, yet the degree to which population response is driven by between-year variation in germination cueing, water limitation or competitive suppression is poorly understood. 2We used demographic monitoring and population models to examine how three seed banking, rare annual plants of the California Channel Islands respond to natural variation in precipitation and their competitive environments. Island plants are particularly threatened by climate change because their current ranges are unlikely to overlap regions that are climatically favourable in the future. 3Species showed 9 to 100-fold between-year variation in plant density over the 5,12 years of censusing, including a severe drought and a wet El Niño year. During the drought, population sizes were low for all species. However, even in non-drought years, population sizes and per capita growth rates showed considerable temporal variation, variation that was uncorrelated with total rainfall. These population fluctuations were instead correlated with the temperature after the first major storm event of the season, a germination cue for annual plants. 4Temporal variation in the density of the focal species was uncorrelated with the total vegetative cover in the surrounding community, suggesting that variation in competitive environments does not strongly determine population fluctuations. At the same time, the uncorrelated responses of the focal species and their competitors to environmental variation may favour persistence via the storage effect. 5Population growth rate analyses suggested differential endangerment of the focal annuals. Elasticity analyses and life table response experiments indicated that variation in germination has the same potential as the seeds produced per germinant to drive variation in population growth rates, but only the former was clearly related to rainfall. 6Synthesis. Our work suggests that future changes in the timing and temperatures associated with the first major rains, acting through germination, may more strongly affect population persistence than changes in season-long rainfall. [source]

    Vision-aided inertial navigation for pin-point landing using observations of mapped landmarks

    Nikolas Trawny
    In this paper we describe an extended Kalman filter algorithm for estimating the pose and velocity of a spacecraft during entry, descent, and landing. The proposed estimator combines measurements of rotational velocity and acceleration from an inertial measurement unit (IMU) with observations of a priori mapped landmarks, such as craters or other visual features, that exist on the surface of a planet. The tight coupling of inertial sensory information with visual cues results in accurate, robust state estimates available at a high bandwidth. The dimensions of the landing uncertainty ellipses achieved by the proposed algorithm are three orders of magnitude smaller than those possible when relying exclusively on IMU integration. Extensive experimental and simulation results are presented, which demonstrate the applicability of the algorithm on real-world data and analyze the dependence of its accuracy on several system design parameters. © 2007 Wiley Periodicals, Inc. [source]

    Multilevel Anthropogenic Cycles of Copper and Zinc: A Comparative Statistical Analysis

    Barbara Reck
    Contemporary cycles for copper and zinc are coanalyzed with the tools of exploratory data analysis. One-year analyses (circa 1994) are performed at three discrete spatial levels-country (52 countries that comprise essentially all anthropogenic stocks and flows of the two metals), eight world regions, and the planet as a whole-and are completed both in absolute magnitude and in per capita terms. This work constitutes, to our knowledge, the first multiscale, multilevel analysis of anthropogenic resources throughout their life cycles. The results demonstrate that (1) A high degree of correlation exists between country-level copper and country-level zinc rates of fabrication and manufacturing, entry into use, net addition to in-use stocks, discard, and landfilling; (2) Regional-level rates for copper and zinc cycle parameters show the same correlations as exist at country level; (3) On a per capita basis, countries add to in-use stock almost 50% more copper than zinc; (4) The predominant discard streams for copper and zinc at the global level are different for the two metals, and relative rates of different loss processes differ geographically, so that resource recovery policies must be designed from metalspecific and location-specific perspectives; (5)When absolute magnitudes of life-cycle flows are considered, the standard deviations of the data sets decrease from country level to regional level for both copper and zinc, which is not the case for the per capita data sets, where the statistical properties of the dat sets for both metals approach being independent of spatial level, thus providing a basis for predicting unmeasured per capita metal flow behavior. [source]

    Does the Agulhas Current amplify global temperatures during super-interglacials?,

    Chris S.M. Turney
    Abstract Future projections of climate suggest our planet is moving into a ,super-interglacial'. Here we report a global synthesis of ice, marine and terrestrial data from a recent palaeoclimate equivalent, the Last Interglacial (ca. 130,116,ka ago). Our analysis suggests global temperatures were on average ,1.5°C higher than today (relative to the AD 1961,1990 period). Intriguingly, we identify several Indian Ocean Last Interglacial sequences that suggest persistent early warming, consistent with leakage of warm, saline waters from the Agulhas Current into the Atlantic, intensifying meridional ocean circulation and increasing global temperatures. This mechanism may have played a significant positive feedback role during super-interglacials and could become increasingly important in the future. These results provide an important insight into a future 2°C climate stabilisation scenario. Copyright © 2010 John Wiley & Sons, Ltd. [source]

    Effect of the challenger experience on elementary children's attitudes to science

    Tina Jarvis
    This research explored how the Challenger experience influenced over 655 elementary boys' and girls' general attitudes to science and space during the 5 months after their visit by examining their responses to four different attitude scales. These were administered to the 10- to 11-year-olds immediately before and after the Challenger experience as well as 2 and 5 months later. Knowledge tests were also administered before and after the visit. A sample of children completed an existing measure of anxiety. Although there were mainly positive outcomes immediately after the Challenger experience, there were some negative effects. There were also noticeable differences between boys and girls. Some 24% of pupils were inspired to become scientists. There was also less fear of space travel with a greater appreciation of the use of science to protect the planet after the visit. Most girls improved and maintained their attitudes toward science in society. A sizeable number of pupils were relatively unaffected by the experience and there was a significant negative effect on a small group of anxious girls. There are indications that previsit preparation and careful choice of roles during the simulation are important. © 2002 Wiley Periodicals, Inc. J Res Sci Teach 39: 979,1000, 2002 [source]

    Impacts of global change on plant diversity and vice versa: Old and new challenges for vegetation scientists

    Frank Berendse
    Abstract. The desire to stop the current dramatic loss of biodiversity has been a major stimulus for many vegetation ecologists to unravel the mechanisms responsible for the coexistence of species. After the Rio Janeiro Convention many ecologists were convinced that nature conservation would gain strong societal support if they could prove that the loss of species would have important negative effects on the ecosystem functions that are relevant to society. I conclude that in order to understand such possible effects, it is necessary to analyse the effects of individual species on those ecosystem processes that we consider to be relevant in the context of specific questions. The great challenge for the near future is to scale the effects of plant species on their local environment up to the level of the whole planet, so that we learn about possible feedbacks that might regulate or destabilize those characteristics of the globe that are essential to our society. [source]

    Hepatitis C virus,biology, host evasion strategies, and promising new therapies on the horizon

    Sohail A. Qureshi
    Abstract Hepatitis C reduces the quality of life for some 170 million people around the globe and is one of the most prevalent diseases on the planet. It is caused by the hepatitis C virus (HCV) that is replicated by an error-prone polymerase and therefore undergoes rapid evolution. To date, although much has been learned about the biology of HCV, only a partially effective combination therapy comprised of ribavirin and pegylated-interferon-, is available to hepatitis C sufferers. Given the prevalence of hepatitis C, together with the fact that almost half the chronically infected HCV patients are refractory to current therapy, there is an urgent need for an efficacious immunoprophylactic that protects individuals from HCV infection, as well as drugs that impede the viral life cycle effectively and eradicate infection. Herein, I provide an overview of the molecular biology of HCV, highlighting the functions of different virally encoded proteins in terms of how they alter signaling pathways of host cell to establish an infection and discuss whether a more promising therapy for treating hepatitis C is anywhere in sight. © 2006 Wiley Periodicals, Inc. Med Res Rev, 27, No. 3, 353,373, 2007 [source]

    The effects of nebula surface density profile and giant-planet eccentricities on planetary accretion in the inner solar system

    Two surface density profiles are examined: a decaying profile with , , 1/a, where a is orbital semi-major axis, and a peaked profile in which , increases for a < 2 AU and decreases for a > 2 AU. The peaked profiles are generated by models of coagulation in an initially hot nebula. Models with initial ej,s = 0.05 (the current value) and 0.1 are considered. Simulations using the decaying profile with ej,s = 0.1 produce systems most like the observed planets in terms of mass-weighted mean a and the absence of a planet in the asteroid belt. Simulations with doubled , produce planets roughly twice as massive as the nominal case. Most initial embryos are removed in each simulation via ejection from the solar system or collision with the Sun. The asteroid belt is almost entirely cleared on a timescale of 10,100 Ma that depends sensitively on ej,s. Most initial mass with a < 2 AU survives, with the degree of mass loss increasing with a. Mass loss from the terrestrial region occurs on a timescale that is long compared to the mass loss time for the asteroid belt. Substantial radial mixing of material occurs in all simulations, but is greater in simulations with initital ej,s = 0.05. The degree of mixing is equivalent to a feeding zone of half width 1.5 and 0.9 AU for an Earth mass planet at 1 AU for the cases ej,s = 0.05 and 0.1, respectively. In simulations with ej,s = 0.05, roughly one-third and 5,10% of the mass contained in final terrestrial planets originated in the region a > 2.5 AU for the decaying and peaked profiles, respectively. In the case ej,s = 0.1, the median mass accreted from a > 2.5 AU is zero for both profiles. [source]

    The sodium tail of Mercury

    A. E. POTTER
    However, when the angle of the ecliptic is near maximum in the northern hemisphere, and Mercury is near its greatest eastern elongation, it can be seen against the western sky for about a half hour after sunset. During these times, we were able to map sodium D2 emission streaming from the planet, forming a long comet-like tail. On 2001 May 26 (U.T.) we mapped the tail downstream to a distance of ,40 000 km. Sodium velocities in the tail increased to ,11 km s,1 at 40 000 km as the result of radiation pressure acceleration. On 2000 June 5 (U.T.) we mapped the cross-sectional extent of the tail at a distance of ,17 500 km downstream. At this distance, the half-power full-width of the emission was ,20 000 km. We estimated the transverse velocity of sodium in the tail to range from 2 to 4 km s,1. The velocities we observed imply source velocities from the planet surface of the order of 5 km s,1, or 4 eV. Particle sputtering is a likely candidate for production of sodium atoms at these velocities. The total flux of sodium in the tail was ,1 times 1023 atoms s,1, which corresponds to 1 to 10% of the estimated total production rate of sodium on the planet. [source]

    Communicating the value of atmospheric services

    John Thornes
    Abstract The atmosphere is one of the most valuable resources on the planet and yet because it is largely invisible it tends to be taken for granted and is increasingly being exploited and commodified. This paper presents 12 Atmospheric Services that are vital to human well-being and the existence of the biosphere. The Total Economic Value of the atmosphere is estimated to be at least between 100 and 1000 times the Gross World Product (GWP was approximately £43 Trillion in 2008). It is only by appreciating the value of the atmosphere to society that we can understand how we need to communicate sustainable management of the atmosphere and treat it as a global commons. It is also important to realize which Atmospheric Services are currently under threat. Only by appreciating the full range of services provided by the atmosphere can the real cost of geo-engineering the climate be calculated. Before geo-engineering of the climate can ever be considered seriously a Law of the Atmosphere will be required. Copyright © 2010 Royal Meteorological Society [source]

    The determination of planetary structure in tidally relaxed inclined systems

    Rosemary A. Mardling
    ABSTRACT The recent discovery of a transiting short-period planet on a slightly non-circular orbit with a massive highly eccentric companion orbiting the star HAT-P-13 offers the possibility of probing the structure of the short-period planet. The ability to do this relies on the system being in a quasi-equilibrium state in the sense that the eccentricities are constant on the usual secular time-scale (typically, a few thousand years), and decay on a time-scale which is much longer than the age of the system. Since the equilibrium eccentricity is effectively a function only of observable system parameters and the unknown Love number of the short-period planet, the latter can be determined with accurate measurements of the planet's eccentricity and radius. However, this analysis relies on the assumption that the system is coplanar, a situation which seems unlikely given the high eccentricity of the outer planet. Here we generalize our recent analysis of this fixed-point phenomenon to mutually inclined systems in which the outer body dominates the total angular momentum, and show that (1) the fixed point of coplanar systems is replaced by a limit cycle in eb,, space, where eb is the eccentricity of the inner planet and , is the angle between the periapse lines, with the average value of eb, e(av)b, decreasing and its amplitude of variation increasing with increasing mutual inclination. This behaviour significantly reduces the ability to unambiguously determine the Love number of the short-period planet if the mutual inclination is higher than around 10°. (2) We show that for Q -values less than 106, the HAT-P-13 system cannot have a mutual inclination between 54° and 126° because Kozai oscillations coupled with tidal dissipation would act to quickly move the inclination outside this range, and (3) that the behaviour of retrograde systems is the mirror image of that for prograde systems in the sense that (almost) identical limit cycles exist for a given mutual inclination and , minus this value. (4) We derive a relationship between e(av)b, the equilibrium radius of the short-period planet, its Q -value and its core mass, and show that given current estimates of eb and the planet radius, as well as the lower bound placed on the Q -value by the decay rate of e(av)b, the HAT-P-13 system is likely to be close to prograde coplanar, or have a mutual inclination between 130° and 135°. Lower rather than higher core masses are favoured. (5) An expression for the time-scale for decay of the mutual inclination is derived, revealing that it evolves towards a non-zero value as long as eb > 0 on a time-scale which is much longer than the age of the system. (6) We conclude with a scattering scenario for the origin of the HAT-P-13 system and show that almost identical initial conditions can result in significantly different outer planet eccentricities, stellar obliquities and planet radii. The implications for systems with high stellar obliquities such as HAT-P-7 and WASP-17 are briefly discussed. [source]

    Distant future of the Sun and Earth revisited

    K.-P. Schröder
    ABSTRACT We revisit the distant future of the Sun and the Solar system, based on stellar models computed with a thoroughly tested evolution code. For the solar giant stages, mass loss by the cool (but not dust-driven) wind is considered in detail. Using the new and well-calibrated mass-loss formula of Schröder & Cuntz, we find that the mass lost by the Sun as a red giant branch (RGB) giant (0.332 M,, 7.59 Gyr from now) potentially gives planet Earth a significant orbital expansion, inversely proportional to the remaining solar mass. According to these solar evolution models, the closest encounter of planet Earth with the solar cool giant photosphere will occur during the tip-RGB phase. During this critical episode, for each time-step of the evolution model, we consider the loss of orbital angular momentum suffered by planet Earth from tidal interaction with the giant Sun, as well as dynamical drag in the lower chromosphere. As a result of this, we find that planet Earth will not be able to escape engulfment, despite the positive effect of solar mass loss. In order to survive the solar tip-RGB phase, any hypothetical planet would require a present-day minimum orbital radius of about 1.15 au. The latter result may help to estimate the chances of finding planets around white dwarfs. Furthermore, our solar evolution models with detailed mass-loss description predict that the resulting tip-AGB (asymptotic giant branch) giant will not reach its tip-RGB size. Compared to other solar evolution models, the main reason is the more significant amount of mass lost already in the RGB phase of the Sun. Hence, the tip-AGB luminosity will come short of driving a final, dust-driven superwind, and there will be no regular solar planetary nebula (PN). The tip-AGB is marked by a last thermal pulse, and the final mass loss of the giant may produce a circumstellar (CS) shell similar to, but rather smaller than, that of the peculiar PN IC 2149 with an estimated total CS shell mass of just a few hundredths of a solar mass. [source]