A near-Earth <a href="/our_solar_system/asteroids.html">asteroid</a> - named 2012 DA14 by astronomers - passed within 17,200 miles from Earth on February 15, 2013. On closest approach at about 1:25 p.m. CST on February 15, although it was within the orbit of the <a href="/earth/moons_and_rings.html">Moon</a> and even geosynchronous <a href="/space_missions/satellites.html">satellites</a>, it didn't strike Earth! Find out more from <a href="http://www.nasa.gov/mission_pages/asteroids/news/asteroid20130201315144.html">NASA</a>! Fragments of a meteorite hit Chelyabinsk, Russia on 2/15/2013 <a href="http://www.reuters.com/article/2013/02/15/us-russia-meteorite-idUSBRE91E05Z20130215">injuring over 500</a>. Learn about <a href="http://www.windows2universe.org/our_solar_system/meteors/meteors.html">meteors and meteorites</a>.<p><small><em>NASA/JPL-CalTech</em></small></p>Lunar eclipses are special events that only occur when certain conditions are met. First of all, the Moon must be in <a href="/the_universe/uts/moon3.html">full phase</a>. Secondly, the <a href="/sun/sun.html">Sun</a>, <a href="/earth/earth.html">Earth</a> and <a href="/earth/moons_and_rings.html">Moon</a> must be in a perfectly straight line. If both of these are met, then the Earth's shadow can block the Sun's light from hitting the Moon. The reddish glow of the Moon is caused by light from the Earth's limb scattering toward the Moon, which is reflected back to us from the Moon's surface.<p><small><em>Image credit - Doug Murray, Palm Beach Gardens, Florida</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">methane</a>, a powerful <a href="/earth/climate/cli_greengas.html">greenhouse gas</a>. Watch the NBC Learn video - <a href="/earth/changing_planet/permafrost_methane_intro.html">Thawing Permafrost and Methane</a> to find out more.<p><small><em>Image courtesy of the USGS</em></small></p>The <a href="http://www.windows2universe.org/earth/Atmosphere/tornado/fujita.html">EF-5</a> <a href="http://www.windows2universe.org/earth/Atmosphere/tornado.html">tornado</a> that hit El Reno, Oklahoma on May 31st, 2013 was the widest ever recorded in the US, according to the National Weather Service in Norman Oklahoma. The tornado, which remained on the ground for 40 minutes and reached 2.6 miles across (4.2 km), took the lives of 18 people including storm chasers Tim Samaras, Paul Samaras and Carl Young.<p><small><em>Image courtesy of National Weather Service, Norman Oklahoma</em></small></p>On May 20, 2013, a massive EF5 <a href="http://www.windows2universe.org/earth/Atmosphere/tornado.html">tornado</a> hit Moore, Oklahoma, devastating communities and lives. The tornado, on the ground for 40 minutes, took a path through a subdivision of homes, destroying block after block of homes, and hitting two elementary schools just as school was ending as well as a hospital. Hundreds of people were injured, and 24 were killed.<p><small><em>Image courtesy of Ks0stm, Creative Commons Attribution-Share Alike 3.0 Unported license</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>


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