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.

Scientists at the University of Michigan have found that <a href="/earth/polar/cryosphere_permafrost1.html&dev=1/earth/Atmosphere/moons/pollution_climate_change.html">permafrost</a> in the <a href="/earth/polar/polar_north.html&dev=1/earth/Atmosphere/moons/pollution_climate_change.html">Arctic</a> is extremely sensitive to sunlight.  Exposure to sunlight releases carbon gases trapped in the permafrost, including <a href="/earth/climate/earth_greenhouse.html&dev=1/earth/Atmosphere/moons/pollution_climate_change.html">climate-warming</a> <a href="/physical_science/chemistry/carbon_dioxide.html&dev=1/earth/Atmosphere/moons/pollution_climate_change.html">carbon dioxide</a>, to the <a href="/earth/Atmosphere/overview.html&dev=1/earth/Atmosphere/moons/pollution_climate_change.html">atmosphere</a> much faster than previously thought.<p><small><em>George Kling, The University of Michigan</em></small></p>As temperatures rise and soil moisture decreases, plants are stressed, which can lead to <a href="/earth/climate/crops_withering.html&dev=1/earth/Atmosphere/moons/pollution_climate_change.html">crop withering</a>. <a href="/teacher_resources/online_courses/health/events_health.html&dev=1/earth/Atmosphere/moons/pollution_climate_change.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="/earth/changing_planet/withering_crops_intro.html&dev=1/earth/Atmosphere/moons/pollution_climate_change.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><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/earth/Atmosphere/moons/pollution_climate_change.html">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>March 2012 marks the first anniversary of the 9.0 magnitude <a href="/earth/geology/quake_1.html&dev=1/earth/Atmosphere/moons/pollution_climate_change.html">earthquake</a>, <a href="/earth/tsunami1.html&dev=1/earth/Atmosphere/moons/pollution_climate_change.html">tsunami</a>, and resulting nuclear accident in Japan on <a href="/headline_universe/march112011earthquaketsunami.html&dev=1/earth/Atmosphere/moons/pollution_climate_change.html">11 March 2011</a>.  The tsunami did massive damage, wiping out entire villages and killing ~16,000 people, and leading to one of the most serious nuclear accidents in history.  This image shows before and after photos of the area north of Sendai, where 10,000 people were lost.<p><small><em>Photos by <a href="http://www.nytimes.com/interactive/2011/03/13/world/asia/satellite-photos-japan-before-and-after-tsunami.html?hp">GeoEye/EyeQ</a>.</em></small></p>Coral animals build reefs in warm, tropical seawater. However, <a href="/earth/changing_planet/ocean_temperatures_intro.html&dev=1/earth/Atmosphere/moons/pollution_climate_change.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>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&dev=1/earth/Atmosphere/moons/pollution_climate_change.html">full phase</a>. Secondly, the <a href="/sun/sun.html&dev=1/earth/Atmosphere/moons/pollution_climate_change.html">Sun</a>, <a href="/earth/earth.html&dev=1/earth/Atmosphere/moons/pollution_climate_change.html">Earth</a> and <a href="/earth/moons_and_rings.html&dev=1/earth/Atmosphere/moons/pollution_climate_change.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>

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