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.

The massive 9.0 magnitude <a href="/earth/geology/quake_1.html&edu=elem&dev=1">earthquake</a> off of Honshu, Japan on <a href="/headline_universe/march112011earthquaketsunami.html&edu=elem&dev=1">11 March 2011</a> generated a <a href="/earth/tsunami1.html&edu=elem&dev=1">tsunami</a> that exceeded 10 meters on the coast near the epicenter.  This image shows model projections for the tsunami wave height in cm which are in good agreement with the observed waves. Our thoughts and prayers are with those who were lost, and their families, as we remember this event.<p><small><em><a href="http://blogs.agu.org/wildwildscience/files/2011/03/680_20110311-TsunamiWaveHeight.jpg">NOAA Tsunami Wave Height Projections image</a></em></small></p>A sinuous glowing band of <a
  href="/earth/Magnetosphere/aurora.html&edu=elem&dev=1">aurora</a> (the Aurora Australis
  or Southern Lights) loops around the <a
  href="/earth/polar/polar_south.html&edu=elem&dev=1">southern polar</a>
region in the
  distance as viewed by astronauts onboard the space shuttle on <a
  href="http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/archives/sts-39.html">STS-039</a>. 
  <a
  href="/earth/Magnetosphere/aurora/aurora_colors.html&edu=elem&dev=1">Aurora are produced</a>
  when <a
  href="/physical_science/physics/atom_particle/particle_radiation.html&edu=elem&dev=1">energetic particles</a>
 entering the Earth's
  atmosphere from space interact with <a
  href="/physical_science/physics/atom_particle/atom.html&edu=elem&dev=1">atoms</a> and <a
  href="/earth/geology/molecule.html&edu=elem&dev=1">molecules</a> in the atmosphere and
  release energy, emitted as light.<p><small><em>Courtesy of NASA, Astronaut Overmeyer and Dr. Hallinan</em></small></p>Scientists are concerned that melting Arctic sea ice will increase the amount of fresh water in the <a href="/earth/polar/arctic_currents.html&edu=elem&dev=1">Beaufort Gyre</a>, which could spill out into the Atlantic and cause major climate shifts in North America and Western Europe. Watch the <a href="/earth/changing_planet/freshwater_arctic.html&edu=elem&dev=1">Changing Planet: Fresh Water in the Arctic video</a>.<p><small><em> Courtesy of Jack Cook, WHOI (<a href="http://www.whoi.edu">Woods Hole Oceanographic Institute</a>)</em></small></p>A view of the Earth as seen by the <a href="/space_missions/apollo17.html&edu=elem&dev=1">Apollo
17</a> crew
while traveling to the
<a href="/earth/moons_and_rings.html&edu=elem&dev=1">Moon</a> on
December 7, 1972.  Africa, Madagascar, and the Arabian Peninsula are
visible, and you can barely make out the
<a href="/earth/polar/antarctica.html&edu=elem&dev=1">Antarctic</a>,
shrouded in the heavy
<a href="/earth/Atmosphere/cloud.html&edu=elem&dev=1">cloud</a> cover
in the southern hemisphere.
Arching cloud patterns show the presence of <a href="/earth/Atmosphere/front.html&edu=elem&dev=1">weather
fronts</a>.<p><small><em>Image courtesy of NASA/Apollo 17.</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&edu=elem&dev=1">full phase</a>. Secondly, the <a href="/sun/sun.html&edu=elem&dev=1">Sun</a>, <a href="/earth/earth.html&edu=elem&dev=1">Earth</a> and <a href="/earth/moons_and_rings.html&edu=elem&dev=1">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>March 2012 marks the first anniversary of the 9.0 magnitude <a href="/earth/geology/quake_1.html&edu=elem&dev=1">earthquake</a>, <a href="/earth/tsunami1.html&edu=elem&dev=1">tsunami</a>, and resulting nuclear accident in Japan on <a href="/headline_universe/march112011earthquaketsunami.html&edu=elem&dev=1">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>

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