<p>The United Nations <a href="http://reliefweb.int/sites/reliefweb.int/files/resources/PAND_report.pdf" target="_blank">estimated</a> that between 1994-2015, there were 6,873 natural disasters worldwide, which affected 218 million people and claimed 1.35 million lives. </p> <p>Check out the materials about natural disasters in <a href="/earth/natural_hazards/when_nature_strikes.html&dev=1/k=/h/neptune/=/ClsManagement.pdf">NBC Learn Videos</a>, and their earth system science connections built up by the related secondary classroom activities.</p><p><small><em>NBC Learn</em></small></p>There are over 900 <a href="/the_universe/uts/megalith.html&dev=1/k=/h/neptune/=/ClsManagement.pdf">rings of stone</a> located in the British Isles. The most famous of these stone rings is of course, <a href="/the_universe/uts/stonehenge.html&dev=1/k=/h/neptune/=/ClsManagement.pdf">Stonehenge</a>. The stones of Stonehenge were put in place between 3,000 B.C and 2,000 B.C. by neolithic people.Some speculate that the site was built as a temple of worship of the ancient Earth deities. Some say it was used as an <a href="/the_universe/uts/stonehenge_astro.html&dev=1/k=/h/neptune/=/ClsManagement.pdf">astronomical observatory</a> of sorts. Still others say it was a burial ground.<p><small><em> Image courtesy of Corel Photography.</em></small></p>As permafrost thaws, the land, atmosphere, water resources, ecosystems, and human communities are affected. Coastal areas and hillsides are vulnerable to erosion by thawing of permafrost. Thawing permafrost also causes a positive feedback to global warming, as carbon trapped within the once-frozen soils is released as <a href="/physical_science/chemistry/methane.html&dev=1/k=/h/neptune/=/ClsManagement.pdf">methane</a>, a powerful <a href="/earth/climate/cli_greengas.html&dev=1/k=/h/neptune/=/ClsManagement.pdf">greenhouse gas</a>. Watch the NBC Learn video - <a href="/earth/changing_planet/permafrost_methane_intro.html&dev=1/k=/h/neptune/=/ClsManagement.pdf">Thawing Permafrost and Methane</a> to find out more.<p><small><em>Image courtesy of the USGS</em></small></p>This historic image is the first ever taken from a spacecraft in orbit about <a href="/mercury/mercury.html&dev=1/k=/h/neptune/=/ClsManagement.pdf">Mercury</a>, the innermost planet of the solar system. Taken on 3/29/2011 by <a href="/space_missions/robotic/messenger/messenger.html&dev=1/k=/h/neptune/=/ClsManagement.pdf">MESSENGER</a>, it shows numerous craters across the <a href="/mercury/Interior_Surface/Surface/surface_overview.html&dev=1/k=/h/neptune/=/ClsManagement.pdf">surface</a> of the planet. Temperatures there can reach over 800F because Mercury is so close to the Sun and rotates so slowly. MESSENGER entered orbit around Mercury earlier in March 2011.<p><small><em>NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington</em></small></p>This first global map of <a href="http://www.windows2universe.org/earth/Water/ocean.html">ocean</a> surface saltiness, released in September 2012 by the NASA Aquarius mission team, shows the distribution of salt in the first 2 cm of the Earth's ocean. <a href="http://www.windows2universe.org/earth/Water/salinity.html">Salinity</a> variations are one of the main drivers of <a href="http://www.windows2universe.org/earth/Water/circulation1.html">ocean circulation</a>, and are closely connected with the <a href="http://www.windows2universe.org/earth/Water/water_cycle.html">cycling of freshwater</a> around the planet. High salinity is seen in the Mediterranean, Atlantic, and the Arabian Sea.<p><small><em>Image courtesy of NASA/GSFC/JPL-Caltech</em></small></p>An artist's rendering of the moment of impact of a massive <a href="/our_solar_system/meteors/meteors.html&dev=1/k=/h/neptune/=/ClsManagement.pdf">meteorite</a> at the end of the Cretaceous (at the end of the <a href="/earth/geology/hist_mesozoic.html&dev=1/k=/h/neptune/=/ClsManagement.pdf">Mesozoic Era</a>). Many scientists have concluded for decades that a meteorite four to six kilometers in diameter impacted the Earth at this time, resulting in a <a href="/earth/past/KTextinction.html&dev=1/k=/h/neptune/=/ClsManagement.pdf">mass extinction of dinosaurs</a> and many other life forms. Recent research suggests that perhaps <a href="/headline_universe/olpa/chicxulub.html&dev=1/k=/h/neptune/=/ClsManagement.pdf">massive volcanic eruptions</a> may be been responsible for the extinction.<p><small><em>Courtesy of Don Davis, NASA</em></small></p>


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Video About Ocean Dead Zones

Oceanographers are using robotic undersea "gliders" to study "dead zones" in the seas. View this video from the National Science Foundation ...Read more
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Clouds in Art

Landscape painters have been representing clouds in their art for centuries. Different artists with different styles have painted clouds differently. Check out the Clouds in Art Interactive ...Read more
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Modeling Space Weather

Computer models help scientists study all aspects of space weather. Models help us understand activity on the Sun, the flow of the solar wind in space, and planetary magnetospheres ...Read more
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Galileo Galilei

Galileo Galilei was an Italian astronomer and physicist who lived between 1564-1642. He was the first person to use a telescope to look at the sky. He discovered sunspots, craters and peaks in the moon ...Read more

Mercury

Mercury is the smallest planet in our Solar System. It is also the closest planet to the Sun, so it is very, very hot. A "year" on Mercury lasts just 88 days ...Read more

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Study of Glacial Earthquakes Shakes Up Idea of How Ice Streams Move

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