Astronomy: Martian illusions
The Mars canal controversy is a reminder to be cautious when interpreting alien worlds, notes Michael Carr.
Nature↗
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Report upon United States geological surveys west of the one hundredth meridian, Volume II: Astronomy and barometric hypsometry
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Monograph↗
Star crossings and stone monuments-Field astronomy by the Wheeler Survey in 1870s Colorado
The decade of the 1870s was a time of extensive exploration and surveying in the American West. The nation needed knowledge of the cultural features, topography, natural resources, and geology of this land to promote and aid the 'rapid development of an empire.' The need was particularly acute in the region that still was known in the early 1870s as Colorado Territory. There, cities and towns were springing up along the base of the Front Range, railroads were expanding, and in the mountains prospectors and miners were exploring the countryside seeking and extracting the region's abundant mineral resources. Also, recurring conflicts between the newcomers and Native Americans made it desirable to have accurate maps for military purposes. Four major government-sponsored scientific surveys formed the principal organized effort to provide critical knowledge of the land. Civilian scientists led three of these: John Wesley Powell ('Geographical and Topographical Survey of the Colorado River of the West'); Ferdinand V. Hayden ('Geological and Geographical Survey of the Territories'); and Clarence King ('Geological Exploration of the Fortieth Parallel'). Lt. George Montague Wheeler, a young graduate of West Point (Class of 1866) and a member of the U.S. Army Corps of Engineers, led the fourth and most ambitious project ('United States Geographical Surveys West of the One Hundredth Meridian').
Circular↗
The origin of neap-spring tidal cycles
The origin of oceanic tides is a basic concept taught in most introductory college-level sedimentology/geology, oceanography, and astronomy courses. Tides are typically explained in the context of the equilibrium tidal theory model. Yet this model does not take into account real tides in many parts of the world. Not only does the equilibrium tidal model fail to explicate amphidromic circulation, it also does not explain diurnal tides in low latitude positions. It likewise fails to explain the existence of tide-dominated areas where neap-spring cycles are synchronized with the 27.32-day orbital cycle of the Moon (tropical month), rather than with the more familiar 29.52-day cycle of lunar phases (synodic month). Both types of neap-spring cycles can be recognized in the rock record. A complete explanation of the origin of tides should include a discussion of dynamic tidal theory. In the dynamic tidal model, tides resulting from the motions of the Moon in its orbit around the Earth and the Earth in its orbit around the Sun are modeled as products of the combined effects of a series of phantom satellites. The movement of each of these satellites, relative to the Earth's equator, creates its own tidal wave that moves around an amphidromic point. Each of these waves is referred to as a tidal constituent. The geometries of the ocean basins determine which of these constituents are amplified. Thus, the tide-raising potential for any locality on Earth can be conceptualized as the result of a series of tidal constituents specific to that region. A better understanding of tidal cycles opens up remarkable opportunities for research on tidal deposits with implications for, among other things, a more complete understanding of the tidal dynamics responsible for sediment transport and deposition, changes in Earth-Moon distance through time, and the possible influences tidal cycles may exert on organisms. ?? 2006 Elsevier B.V. All rights reserved.
Marine Geology↗
Interoperability in planetary research for geospatial data analysis
For more than a decade there has been a push in the planetary science community to support interoperable methods for accessing and working with geospatial data. Common geospatial data products for planetary research include image mosaics, digital elevation or terrain models, geologic maps, geographic location databases (e.g., craters, volcanoes) or any data that can be tied to the surface of a planetary body (including moons, comets or asteroids). Several U.S. and international cartographic research institutions have converged on mapping standards that embrace standardized geospatial image formats, geologic mapping conventions, U.S. Federal Geographic Data Committee (FGDC) cartographic and metadata standards, and notably on-line mapping services as defined by the Open Geospatial Consortium (OGC). The latter includes defined standards such as the OGC Web Mapping Services (simple image maps), Web Map Tile Services (cached image tiles), Web Feature Services (feature streaming), Web Coverage Services (rich scientific data streaming), and Catalog Services for the Web (data searching and discoverability). While these standards were developed for application to Earth-based data, they can be just as valuable for planetary domain. Another initiative, called VESPA (Virtual European Solar and Planetary Access), will marry several of the above geoscience standards and astronomy-based standards as defined by International Virtual Observatory Alliance (IVOA). This work outlines the current state of interoperability initiatives in use or in the process of being researched within the planetary geospatial community.
Planetary and Space Science↗
III.-The Work of Prof. Henry Carvill Lewis in Glacial Geology
The recent notice of the life and work of Prof. Henry Carvill Lewis, whose lamented death occurred in Manchester, July 21st, 1888, in his thirty-fifth year, well indicates the wide range of his scientific labours. He published valuable results of investigations in astronomy, mineralogy and petrology, and especially in glacial geology, the last being based on his exploration of the drift and its terminal moraines in the United States, and later in Ireland, Wales and England. The present article reviews his contributions to our knowledge of these drift formations and of the history of the Ice Age, bringing into comparison and correlation the glacial records of America and Europe. Comprehensive as were Professor Lewis' observations and studies in this field, he was planning yet more thorough and extensive exploration of the drift in Britain, Germany and Scandinavia, when he was taken from us.
Geological Magazine↗
Extreme volcanism on Io: Latest insights at the end of Galileo era
Galileo has now completed 7 years exploring Jupiter. The spacecraft obtained breathtaking views of the four major satellites, and studied Jupiter's clouds and atmospheric composition, rings, small satellites, and magnetic field. It had five successful close flybys and many distant observations of Io. Scientists already knew from Voyager and Earth‐based astronomy that Io is by far the most volcanically active object in the solar system. Galileo has given us stunning color panoramas of Io's surface and unprecedented close views of erupting volcanoes (Figure 1) and the largest active flows observed anywhere. Among recent discoveries about Io, perhaps most astonishing since Voyager, is that some lavas possess emission temperatures greater than any lavas erupted on Earth today and possibly since the start of Earth's geologic history. The Io science community has identified three alternative interpretations of Io's hottest lavas: (1) ultramafic material similar to komatiite; (2) superheated lava; or (3) an ultra‐refractory substance deficient in silica and rich in Ca‐Al oxides.
Eos, Transactions, American Geophysical Union↗
Geographic data from space
Space science has been called “the collection of scientific problems to which space vehicles can make some specific contributions not achievable by ground-based experiments.” Geography, the most spatial of the sciences, has now been marked as one of these “space sciences.” The National Aeronautics and Space Administration (NASA) is sponsoring an investigation to identify the Potential geographic benefits from the nation’s space program. This is part of NASA’s long-range inquiry to determine the kinds of scientific activities which might profitably be carried out on future space missions. Among such future activities which are now being planned by NASA are a series of manned earth orbital missions, many of which would be devoted to research. Experiments in physics, astronomy, geophysics, meteorology, and biology are being discussed for these long-range missions. The question which is being put to geographers is, essentially, what would it mean to geographic research to have an observation satellite (or many such satellites) orbiting the earth, gathering data about earth-surface features and environments?
Professional Geographer↗
Communicating darkness: Visitor preferences for dark sky interpretation
Utah parks are attracting an increasing number of visitors due to the quality dark sky viewing opportunities. Despite increasing engagement in nighttime recreation, limited research exists on visitor interest in interpretation for dark skies in state and national parks. Nighttime visitors at nine Utah state and national park units certified as dark sky parks were surveyed to evaluate their preferences for dark sky-related interpretive topics and communication methods. Visitors expressed the strongest interest in astronomy and improving dark sky viewing, with ranger-led programs emerging as the most favored delivery method. National park visitors showed greater interest than state park visitors in self-guided learning formats such as interpretive displays and mobile apps for topics such as dark sky viewing/astronomy and viewing wildlife at night. These findings highlight the benefits of diverse, yet targeted communication strategies to improve visitor experiences of dark skies and foster stewardship of natural darkness in parks.
Utah↗
Lewis and Clark's observations and measurements of geomorphology and hydrology, and changes with time
Two VERY different men, Meriwether Lewis and William Clark, joined to J, ~ake the first recorded set of scientific observations and measurements of geomorphology and hydrology west of the Mississippi River. They did not limit themselves to these two scientific topics but were true naturalists, making observations and measurements related to astronomy (Large, 1979; Bedini, 1984; Plamondon, 1991; Bergantino, 1998), biology (Cutright, 1969), ecology, ethnology (Ronda, 1984a), geology (Bluemle, 2001; Bergantino, 1998), and phenology, as well as to the general geographical understanding of the arrangements of rivers and other topographical features of the trans-Mississippi West (Allen, 1975) .
Circular↗
Sir Harold Jeffreys
Sir Harold Jeffreys is a world authority in theoretical geophyiscs. hew as born in Northumbria (northeast of England) and educated at Armstrong College (now the University of Newcastle-upon-Tyne) and Cambridge University. He is now a Senior Fellow of St.John's College, Cambridge. He has published over 300 scientific papers and is the author of 7 books, including Theory of Probability and Mathematical Physics (with his wife, Lady Bertha Swirles Jeffreys) . Sir Harold has made innumerable theoretical contributions to seismology. Many of these are documented in his book The Earth , which has been published in six editions. His papers have recently been collated by Gordon and Breach (Publishers) into six volumes, Collected Papers on Sir Harold Jeffreys on Geophyiscs and other Sciences. Some idea of the breadth of this research can be seen from the individual volume titles: "Theoretical and Observational Seismology," "Observational Seismology," "Gravity," "Dissipation of Energy and Thermal History," "Astronomy and Geophysics," and "Matematics, Probability and Miscellaneious Other Sciences."
Earthquake Information Bulletin (USGS)↗
Worldwide standardized seismograph network
A global network of seismographs is as indispensable to seismologists as telescopes are to astronomers. The network is used to catalog the thousands of earthquakes that occur each year and to provide the data needed for detailed studies of earthquake mechanisms, deep Earth structure, and tectonic processes. Like astronomy, seismology is an observational science, and most of the scientific advances have been preceded by improvements in instrument technology. To be useful for seismic studies, new technology must be applied on a global scale. During the past two decades, there has been notable success in meeting this objective. The network that exists today (fig. 1) is a vital scientific resource. Continued innovations and improvements are needed to insure that its keeps pace with the data needs of the seismological community.
Earthquake Information Bulletin (USGS)↗
Neither a year nor an annus can be a derived unit in the SI
The year is not a unit of the SI. The only SI unit of measurement for time is the second. The word “annus” or “annum” does not appear anywhere in the current SI document. The word “year” is not in the table of “Non-SI units accepted for use with the International System of Units,” nor in the table of “Non-SI units whose values in SI units must be obtained experimentally,” nor even in the table of “Other non-SI units.” The year can be found, however, through the list of “Other non-SI units not recommended for use.” This heading directs the reader to a National Institute of Standards and Technology (NIST) list where three kinds of year (365 days, sidereal, and tropical) are given with conversion to seconds, but are set in type to indicate “in general not to be used in NIST publications.” Table 1 summarizes some of the uses of the year in other publications. For example, in the IUPAC chemistry document, the year is not a constant; in the International Astronomy Union Style Guide, the year (Julian) is a constant.
Chemistry International↗
Report of the IAU/IAG Working Group on cartographic coordinates and rotational elements: 2006
Every three years the IAU/IAG Working Group on Cartographic Coordinates and Rotational Elements revises tables giving the directions of the poles of rotation and the prime meridians of the planets, satellites, minor planets, and comets. This report introduces improved values for the pole and rotation rate of Pluto, Charon, and Phoebe, the pole of Jupiter, the sizes and shapes of Saturn satellites and Charon, and the poles, rotation rates, and sizes of some minor planets and comets. A high precision realization for the pole and rotation rate of the Moon is provided. The expression for the Sun's rotation has been changed to be consistent with the planets and to account for light travel time ?? 2007 Springer Science+Business Media B.V.
Celestial Mechanics and Dynamical Astronomy↗
Report of the IAU Working Group on cartographic coordinates and rotational elements: 2009
Every three years the IAU Working Group on Cartographic Coordinates and Rotational Elements revises tables giving the directions of the poles of rotation and the prime meridians of the planets, satellites, minor planets, and comets. This report takes into account the IAU Working Group for Planetary System Nomenclature (WGPSN) and the IAU Committee on Small Body Nomenclature (CSBN) definition of dwarf planets, introduces improved values for the pole and rotation rate of Mercury, returns the rotation rate of Jupiter to a previous value, introduces improved values for the rotation of five satellites of Saturn, and adds the equatorial radius of the Sun for comparison. It also adds or updates size and shape information for the Earth, Mars’ satellites Deimos and Phobos, the four Galilean satellites of Jupiter, and 22 satellites of Saturn. Pole, rotation, and size information has been added for the asteroids (21) Lutetia, (511) Davida, and (2867) Šteins. Pole and rotation information has been added for (2) Pallas and (21) Lutetia. Pole and rotation and mean radius information has been added for (1) Ceres. Pole information has been updated for (4) Vesta. The high precision realization for the pole and rotation rate of the Moon is updated. Alternative orientation models for Mars, Jupiter, and Saturn are noted. The Working Group also reaffirms that once an observable feature at a defined longitude is chosen, a longitude definition origin should not change except under unusual circumstances. It is also noted that alternative coordinate systems may exist for various (e.g. dynamical) purposes, but specific cartographic coordinate system information continues to be recommended for each body. The Working Group elaborates on its purpose, and also announces its plans to occasionally provide limited updates to its recommendations via its website, in order to address community needs for some updates more often than every 3 years. Brief recommendations are also made to the general planetary community regarding the need for controlled products, and improved or consensus rotation models for Mars, Jupiter, and Saturn.
Celestial Mechanics and Dynamical Astronomy↗
Report of the IAU Working Group on Cartographic Coordinates and Rotational Elements: 2015
This report continues the practice where the IAU Working Group on Cartographic Coordinates and Rotational Elements revises recommendations regarding those topics for the planets, satellites, minor planets, and comets approximately every three years. The Working Group has now become a “functional working group” of the IAU and its membership is open to anyone interested in participating. We describe the procedure for submitting questions about the recommendations given here or the application of these recommendations for creating a new or updated coordinate system for a given body. Regarding body orientation, the following bodies have been updated: Mercury, based on MESSENGER results; Mars, along with a refined longitude definition; Phobos; Deimos; (1) Ceres; (52) Europa; (243) Ida; (2867) Šteins; Neptune; (134340) Pluto and its satellite Charon; comets 9P/Tempel 1, 19P/Borrelly, 67P/Churyumov-Gerasimenko, and 103P/Hartley 2, noting that such information is valid only between specific epochs. The special challenges related to mapping 67P/Churyumov-Gerasimenko are also discussed. Approximate expressions for the Earth have been removed in order to avoid confusion, and the low precision series expression for the Moon’s orientation has been removed. The previously on-line only recommended orientation model for (4) Vesta is repeated with an explanation of how it was updated. Regarding body shape, text has been included to explain the expected uses of such information, and the relevance of the cited uncertainty information. The size of the Sun has been updated and notation added that the size and the ellipsoidal axes for the Earth and Jupiter have been recommended by an IAU Resolution. The distinction of a reference radius for a body (here, the Moon and Titan) is made between cartographic uses, and for orthoprojection and geophysical uses. The recommended radius for Mercury has been updated based on MESSENGER results. The recommended radius for Titan is returned to its previous value. Size information has been updated for 13 other Saturnian satellites and added for Aegaeon. The sizes of Pluto and Charon have been updated. Size information has been updated for (1) Ceres and given for (16) Psyche and (52) Europa. The size of (25143) Itokawa has been corrected. In addition, the discussion of terminology for the poles (hemispheres) of small bodies has been modified and a discussion on cardinal directions added. Although they continue to be used for planets and their satellites, it is assumed that the planetographic and planetocentric coordinate system definitions do not apply to small bodies. However, planetocentric and planetodetic latitudes and longitudes may be used on such bodies, following the right-hand rule. We repeat our previous recommendations that planning and efforts be made to make controlled cartographic products; newly recommend that common formulations should be used for orientation and size; continue to recommend that a community consensus be developed for the orientation models of Jupiter and Saturn; newly recommend that historical summaries of the coordinate systems for given bodies should be developed, and point out that for planets and satellites planetographic systems have generally been historically preferred over planetocentric systems, and that in cases when planetographic coordinates have been widely used in the past, there is no obvious advantage to switching to the use of planetocentric coordinates. The Working Group also requests community input on the question submitting process, posting of updates to the Working Group website, and on whether recommendations should be made regarding exoplanet coordinate systems.
Celestial Mechanics and Dynamical Astronomy↗
Correction to: Report of the IAU Working Group on cartographic coordinates and rotational elements: 2015
We point out some errors in the most recent report from the International Astronomical Union (IAU) Working Group on Cartographic Coordinates and Rotational Elements (Archinal et al. 2018). We correct a sign error in Figs. 1 and 2. We also correct the equation for the prime meridian position (W) of Mars’ satellite Phobos in Table 2.
Celestial Mechanics and Dynamical Astronomy↗
Cryovolcanic rates on Ceres revealed by topography
Cryovolcanism, defined here as the extrusion of icy material from depth, may be an important planetary phenomenon in shaping the surfaces of many worlds in the outer Solar System and revealing their thermal histories 1 , 2 , 3 . However, the physics, chemistry and ubiquity of this geologic process remain poorly understood, especially in comparison to the better-studied silicate volcanism on the terrestrial planets. Ceres is the only plausibly cryovolcanic world to be orbited by a spacecraft up to now, making it the best opportunity to test the importance of cryovolcanism on bodies in the outer Solar System and compare its effects to silicate volcanism on terrestrial planets. Here, we analyse images from NASA’s Dawn mission 4 and use the finite element method to show that Ceres has experienced cryovolcanism throughout its geologic history, with an average cryomagma extrusion rate of ~10 4 m 3 yr −1 . This result shows that volcanic phenomena are important on Ceres, but orders of magnitude less so than on the terrestrial planets.
Nature Astronomy↗