HTML5 microdata markup validation

HTML5 introduces the microdata concept to web page design: HTML elements can semantically be annotated by using item attributes such as itemscope, itemtype and itemprop. Typically, I am using the W3C Markup Validation Service at validator.w3.org to test my HTML5 pages and have experienced good results in checking markup validity. The good news is the bad news: the W3C validator is rather strict and—unfortunately—is too picky when it comes to microdata. For example, it reports errors detected in the shown code snippet, although this code has correct HTML5 syntax.

The code example illustrates annotation of a short text about a chemical substance. This code employs microdata (property/value pairs) according to the vocabulary defined at www.axeleratio.com/voc/chemid. The W3C validator complains about the item attributes, declaring that their use is not allowed on the selected elements at this point. In contrast, the (X)HTML5 Validator at html5.validator.nu declares that this code is valid HTML5, after submitting a page containing this code snippet. The NU Markup Validation Service at qa-dev.w3.org:8888/html5 came up with the same result. The latter validator—according to the statement on its site—checks the markup validity like the current W3C validation service, but instead uses the backend of the Validator.nu engine, which provides non-DTD-based validation support for a number of markup languages. Currently, this latter service is a potentially unstable pilot version, provided for demonstration and testing purposes only.

Suggested sites for microdata digging: 
W3C: www.w3.org/TR/microdata/
Wikipedia: en.wikipedia.org/wiki/Microdata_%28HTML%29
Tutorials Point: www.tutorialspoint.com/html5/html5_microdata.htm
Google: support.google.com/webmasters/bin/answer.py?hl=en&answer=176035

Gale crater on Mars named after Australian banker and astronomer Walter Frederick Gale

The Gale crater on Mars was named in 1991 after Australian banker and astronomer Walter Frederick Gale (1865-1945) [1-3]. This 150-kilometer-wide hollow emerged as the front-runner for the landing site of NASA's Curiosity rover and finally was picked for the $2.5 billion rover mission, successfully launched at the end of November in 2011 [3-5].

The leaders of the Curiosity mission chose the Gale crater as landing spot, because it promises to be the scene for exciting studies of Martian sedimentary patterns by using rock-vaporizing lasers, gas chromatography, mass spectrometry and X-ray diffraction instruments for chemical analysis as well as high-resolution digital cameras from Malin Space Science Systems (MSSS)  [6]. Channels (probably carved by flowing water) in the crater wall and mid-crater mound have been found during previous orbit-based studies:  the mound in the center of the five-kilometer-deep impact crater contains layered materials including clay and other minerals [7].

Keywords: astronomy, planetary science, areography, Martian topography, geology, terminology.

References and more to explore
[1] Google Mars Lab: www.google.com/mars/.
[2] Harley Wood: Gale, Walter Frederick (1865-1945). Australian Dictionary of Biography [adb.anu.edu.au/biography/gale-walter-frederick-6269].
[3] Space News: NASA Picks Gale Crater for Mars Science Lab Landing. July 25, 2011 [www.spacenews.com/civil/110725-nasa-picks-gale-crater-msl.html].
[4] Nancy Atkinson: Gale crater reported front-runner for MSL landing site. June 24, 2011 [www.physorg.com/news/2011-06-gale-crater-front-runner-msl-site.html].
[5] James Holloway: Mars Curiosity Rover successfully launched. November 27, 2011 [http://www.gizmag.com/mars-curiosity-launch-nasa/20627/].
[6] Eric Hand: The Mars Observer. Nature, November 24, 2011, 479 (7374), pp. 460-463 [www.nature.com/news/mike-malin-the-mars-observer-1.9402].
[7] NASA Mars Science Laboratory > Gale Crater: mars.jpl.nasa.gov/msl/mission/timeline/prelaunch/landingsiteselection/galecrater2/.

Martian locality inside the Gusev Crater: Columbia Hills named to honor the crew of the space shuttle Columbia

The Columbia hills inside Crater Gusev on Mars are named to honor the crew of the space shuttle Columbia, which disintegrated over Texas after re-entry into Earth's atmosphere in February 2003 [1,2].

The Columbia Hills are a range of low hills inside Gusev Crater that were visited in 2004 by Mars rover Spirit, equipped with alpha particle X-ray spectrometer (APXS) as well as infrared and Mössbauer spectrometer [3]. With this technology on board, at least ten different types of rocks were identified at the Columbia site, which is exposing rock formations that are different and older than the lava-flooded surroundings of olevine-bearing basalts [1,4]: layered granular deposits were discovered in the Columbia Hills and have been interpreted to be volcanic ash and/or impact ejecta deposits that have been modified by aqueous fluids.

Keywords: astronomy, planetary science, areography, Martian topography, geology, space shuttle Columbia disaster, terminology.

References and more to explore
[1] Ulf von Rauchhaupt: Der Neunte Kontinent - Die wissenschaftliche Eroberung des Mars. Fischer Taschenbuch Verlag, Frankfurt am Main, November 2010; pages 181.
[2] Joseph Lorenzo Hall: Columbia and Challenger: organizational failure at NASA. Space Policy 2003, 19, pp. 239-247 [josephhall.org/papers/nasa.pdf].
[3] mindat.org > Columbia Hills, Gusev Crater, Aeolis quadrangle, Mars: www.mindat.org/loc-189893.html.
[4] R. E. Arvidson et al.: Overview of the Spirit Mars Exploration Rover Mission to Gusev Crater: Landing Site to Backstay Rock in the Columbia Hills. J. Geophys. Res. 2006, 111, E02S01 [si-pddr.si.edu/jspui/bitstream/10088/3547/1/200640.pdf].

Eberswalde Crater on Mars named after the City of Eberswalde in the German State of Brandenburg

The Eberswalde Crater on Mars is named after the German town with the same name (in accordance with the rules for planetary nomenclature of the International Astronomical Union), located about 50 km northeast of Berlin in the German Federal State (Bundesland) of  Brandenburg [1,2]. The 65-km-diameter crater (centered at 24.3°S, 33.5°W, just north of the Holden Crater) contains a distributary fan, which is supposed to be an ancient delta in which a river deposited sediments, now hardened to sandstone [3].  The delta structure is (so far) the most convincing sign that a Martian river once flowed into a standing body of water [4,5]: possible streambed features, which are now higher than the surrounding terrain due to sediment hardening and erosion resistance, are assumed to be remaining parts that formed when the Eberswalde streams carved new channels.   

The Eberswalde Crater and its interesting geology came into focus in 2003 during the Mars Global Surveyor exploration program [6]. Based on images taken during this remote expedition, Michael Malin and Kenneth Edgett of Malin Space Science Systems discovered the Eberswalde delta with a surface are of 115 km² [7].

Keywords: astronomy, planetary science, areography, Martian topography, impact crater, Margaritifer Terra, history, terminology.

References and more to explore
[1] Ulf von Rauchhaupt: Der Neunte Kontinent - Die wissenschaftliche Eroberung des Mars. Fischer Taschenbuch Verlag, Frankfurt am Main, November 2010; pages 174 and 175.
[2] Mahalo > Eberswalde (crater): www.mahalo.com/eberswalde-crater/.
[3] David Pratt: Life on Mars: from microbes to monuments. December 2011 [davidpratt.info/mars-life.htm].
[4]  NASA Mars Science Laboratory > Possible MSL Landing Site: Eberwalde Crater: hmars.jpl.nasa.gov/msl/mission/timeline/prelaunch/landingsiteselection/eberswalde2/.
[5] M. Pondrelli, A. P. Rossi, L. Marianangeli, E. Hauber, K. Gewinner, A. Baliva and S. di Lorenzo: Evolution and depositional environments of the Eberswalde fan delta, Mars. Icarus October 2008, 197 (2), pp. 429-451.
doi: 10.1016/j.icarus.2008.05.018.
[6] NASA Solar System Exploration > Mars Global Surveyor: solarsystem.nasa.gov/missions/profile.cfm?MCode=MGS.
[7] slashtheseats.com/rrpedia/Eberswalde_%28crater%29.

Valles Marineris, a Martian rift zone named to honor the scientific team of the Mariner 9 program

The Valles Marineris got their name in 1973 to honor the scientific team of the Mariner 9 program [1]. The term “Valles Marineris” is the latinized form of the phrase “Mariner Valleys.” “Valles” is the plural form of the Latin noun “vallis.” The plural form in “Valles Marineris” indicates that this vast Martian surface feature is a system of multiple valleys or canyons.

Valles Marineris was discovered in 1972 by the Mariner 9 spacecraft [3]: Its length matches the distance between New York City and Los Angeles. This valley system, commonly referred to as the Valles Marineris trough system, is located close to the Martian equator, where it trends east-west from longitude 40°W to 110°W with a depth reaching 10 km [4]. During NASA's Global Surveyor Mission, the deepest point was found by laser measurements within the valleys in the Coprates Chasma region [5,6]: Valles Marineris does not exhibit the typical features of a river bed or canyon formed by water flowing down from source to delta. A complete understanding of how the Valles Marineris system originated and evolved by combination of water flow, magmatic processes, tensional fracturing and/or other forces is still far away.  

Keywords: astronomy, planetary science, areography, Martian topography, Latin, vallis, valles, terminology.

References and more to explore
[1] Google Mars Lab: www.google.com/mars.
[2] Glossary of Latin Words > V: www.bible-history.com/latin/latin_v.html.
[3] Valles Marineris, a Martian Rift Zone: themis.asu.edu/feature/16.
[4] Géomorphologie > New insight on genetic links between outflows and chasmata on Valles Marineris plateau, Mars (January 2009): geomorphologie.revues.org/7485.
[5] ESA Mars Express > Coprates Chasma and Coprates Catena: www.esa.int/esaMI/Mars_Express/SEMIRE1DU8E_0.html.
[6] Ulf von Rauchhaupt: Der Neunte Kontinent - Die wissenschaftliche Eroberung des Mars. Fischer Taschenbuch Verlag, Frankfurt am Main, November 2010; pages 114 to 119.

The Latin nouns “planitia” and “planum” both mean “plain”—in astronomy “low plain” and “high plain,” respectively

The Latin nouns planitia and planum both mean flat surface, plain or level ground [1,2]. Their plural forms are planitiae and plana, respectively. In astronomy, the meaning of these words have a significance of distinguishing topographical areas: planitia stands for low plain and planum for high plain [1-3].

Triggered by new data on Martian topography delivered by the Mariner 9 mission, the International Astronomical Union (IAU) decided in 1973 on a nomenclature in which the term planitia refers to a plain below the zero-elevation level and the term planum refers to an elevated plain (plateau) [3].

This terminology is now applied to various celestial objects. For example, planitiae of different size are known on planets Mars and Venus as well as on moons in the solar system [4]. Similarly, a large number of plana have been described on Mars, Venus, Neptun moon Triton and Jupiter moon Io [5]. Of course, their are planitiae and plana on Earth (with the standard sea level as zero elevation), but typically their names are derived without incorporating these two Latin nouns.

Keywords: astronomy, planetary science, areography, geological features, Latin, terminology.

References and more to explore
[1] Wiktionary > planitia [en.wiktionary.org/wiki/planitia] and planum [en.wiktionary.org/wiki/planum].
[2] MyEtymology > Etymology of the Latin word planitia [www.myetymology.com/latin/planitia.html] and Etymology of the Latin word planum [www.myetymology.com/latin/planum.html].
[3] Ulf von Rauchhaupt: Der Neunte Kontinent - Die wissenschaftliche Eroberung des Mars. Fischer Taschenbuch Verlag, Frankfurt am Main, November 2010; page 107. (Tiefebene und Hochebene are the German words for planitia  and planum).
[4] FindTheData > Astrogeology > Planitia, planitiae: astrogeology.findthedata.org/d/d/Europe/Planitia,-planitiae.
[5] FindTheData > Astrogeology > Planum, plana: astrogeology.findthedata.org/d/d/Europe/Planum,-plana.

Craters Airy and Airy-0 on Mars named after Greenwich astronomer Sir George Biddell Airy

The craters Airy and Airy-0 on Mars were named to commemorate the Greenwich astronomer Sir George Biddell Airy (1801-1892) [1]: Airy-0, a small impact crater with a diameter of 500 meter, is located inside the 40-kilometer-wide Airy crater in the east-west stretching Sinus Meridiani feature just south of the Martian equator.

The center of Airy-0 was chosen to define the Martian prime meridian, the zero point of longitude. On Earth the prime meridian was defined by international agreement in 1881 based on the location of the Royal Observatory in Greenwich near London, England, where Sir Airy was employed as the seventh Astronomer Royal [1,2].
 
Pinpointing the zero point onto Airy-0 became possible in 1972, when Mariner 9 mapped the surface of Mars at about 1 kilometer resolution [2]:  Merton Davies of the RAND Corporation, who computed an extensive 'control net' of locations, designated Airy-0 as the reference point for the Martian spherical coordinate system. Planet Mars, however, is not exactly a sphere. Like Earth, Mars is flattened at its poles. The overall shape of Mars may be described as a pear, which is further deformed by structures such as the Tharsis Bulge, an uplifted continent about the size of North America [1,3]. 

George Biddell Airy was born at Alnwick in Northumberland on July 27, 1801.  In 1823, he took his B. A. Degree at Trinity College, Cambridge, where he was appointed Plumian Professor of Astronomy at the Cambridge Observatory in 1828. From 1835 until his retirement in 1881 he was Astronomer Royal at the national observatory in Greenwich, where—during his long career and succession of accomplishments in physics, in particular planetary science— he established the prime meridian in the early 1850s [4,5].

Keywords: astronomy, mathematics, geometry, planetary science, areology (science of Mars), areography (geology of Mars), terminology.

References and more to explore
[1] Ulf von Rauchhaupt: Der Neunte Kontinent - Die wissenschaftliche Eroberung des Mars. Fischer Taschenbuch Verlag, Frankfurt am Main, November 2010; pages 104 and 105.
[2] NASA National Aeronautics and Space Administration > Mars Atlas: mars.jpl.nasa.gov/gallery/atlas/PIA03207.html.
[3] The Tharsis Bulge on Mars: http://hyperphysics.phy-astr.gsu.edu/hbase/solar/marsthar.html.
[4] George Biddell Airy: Autobiography of Sir George Biddell Airy (edited by Wilfrid Airy in 1896, produced by Joseph Myers and PG Distributed Proofreaders and released on January 9, 2004) [www.gutenberg.org/cache/epub/10655/pg10655.html].
[5] Sir George Biddell Airy K.C.B., M.A., LL.D., D.C.L., F.R.S., F.R.A.S.:   wwp.greenwich2000.com/heritage/vip/astronomers/airy.htm.