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Earth

Earth, our home planet, is a beautiful blue and white ball when seen from space. The third planet from the Sun, it is the largest of the inner planets. Earth is the only planet known to support life and to have liquid water at the surface. Earth has a substantial atmosphere and magnetic field, both of which are critical for sustaining life on Earth. Earth is the innermost planet in the solar system with a natural satellite – our Moon. Explore our beautiful home planet – unique in our solar system - through the links in this section.

An <a href="http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/usc000905e.php">8.6 magnitude earthquake</a> struck on 11 April 2012 off of Banda Aceh, Sumatra, Indonesia, followed by a strong aftershock.  Earthquake motion was primarily horizontal.  A tsunami warning was issued for the Indian Ocean, but was cancelled at 12:36 UTC.  A tsunami was observed at 1 meter or less. Find out more about <a href="/php/tour_test_sqli.php?page=/earth/geology/quake_1.html">earthquake</a> and <a href="/php/tour_test_sqli.php?page=/earth/tsunami1.html">tsunami</a> processes. Check out the resources <a href="/php/tour_test_sqli.php?page=/teacher_resources/2011_AGU-NESTA_GIFT_Workshop.html">here</a>.<p><small><em>NOAA</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>A view of the Earth as seen by the <a href="/php/tour_test_sqli.php?page=/space_missions/apollo17.html">Apollo
17</a> crew
while traveling to the
<a href="/php/tour_test_sqli.php?page=/earth/moons_and_rings.html">Moon</a> on
December 7, 1972.  Africa, Madagascar, and the Arabian Peninsula are
visible, and you can barely make out the
<a href="/php/tour_test_sqli.php?page=/earth/polar/antarctica.html">Antarctic</a>,
shrouded in the heavy
<a href="/php/tour_test_sqli.php?page=/earth/Atmosphere/cloud.html">cloud</a> cover
in the southern hemisphere.
Arching cloud patterns show the presence of <a href="/php/tour_test_sqli.php?page=/earth/Atmosphere/front.html">weather
fronts</a>.<p><small><em>Image courtesy of NASA/Apollo 17.</em></small></p>Coral animals build reefs in warm, tropical seawater. However, <a href="/php/tour_test_sqli.php?page=/earth/changing_planet/ocean_temperatures_intro.html">seawater can be too warm</a> for their liking.  If waters get too warm, coral animals lose the algae that live within their little bodies, a process called coral bleaching. Without the algae, corals have less nutrition. Unless cooler temperatures return, allowing algae to
 return, the coral dies.<p><small><em>Credit: UNC</em></small></p>As temperatures rise and soil moisture decreases, plants are stressed, which can lead to <a href="/php/tour_test_sqli.php?page=/earth/climate/crops_withering.html">crop withering</a>. <a href="/php/tour_test_sqli.php?page=/teacher_resources/online_courses/health/events_health.html">Droughts</a> accompanied by increased temperatures can lead to famine, social and political disruptions. Scientists are  helping with early identification of drought that might trigger food shortages. Watch the NBC Learn video - <a href="/php/tour_test_sqli.php?page=/earth/changing_planet/withering_crops_intro.html">Changing Planet: Withering Crops</a> to find out more.<p><small><em>Image taken by Tomas Castelazo, Creative Commons <a href=&quot;http://creativecommons.org/licenses/by/3.0/deed.en&quot;>Attribution 3.0 Unported</a> license.</em></small></p>A new study has found that <a href="/php/tour_test_sqli.php?page=/earth/Atmosphere/airpollution_intro.html">pollution</a> from <a href="/php/tour_test_sqli.php?page=/earth/Atmosphere/particulates.html">fine particles</a> in the air - mainly the result of burning coal or <a href="/php/tour_test_sqli.php?page=/earth/interior/eruptions.html">volcanic eruptions</a> - can shade <a href="/php/tour_test_sqli.php?page=/earth/Life/cnidarian.html">corals</a> from sunlight and cool the surrounding water resulting in reduced growth rates.  Coral growth rates in the Caribbean were affected by volcanic aerosol emissions in the early 20th century and by aerosol emissions caused by humans in the later 20th century.  For more information, see the <a href="http://www.exeter.ac.uk/news/featurednews/title_278202_en.html">press release</a>.<p><small><em>Image courtesy of Toby Hudson (Wikimedia Commons)</em></small></p>

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF