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.

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">methane</a>, a powerful <a href="/earth/climate/cli_greengas.html&dev=1">greenhouse gas</a>.
Watch the NBC Learn video - <a href="/earth/changing_planet/permafrost_methane_intro.html&dev=1">Thawing Permafrost and Methane</a> to find out more.<p><small><em>Image courtesy of the    USGS</em></small></p>How did life evolve on <a href="/earth/earth.html&dev=1">Earth</a> during the <a href="/earth/past/Archean.html&dev=1">Archean</a>, when the <a href="/sun/sun.html&dev=1">Sun</a> was about 25% weaker than today?  The Earth should have been <a href="/earth/polar/cryosphere_glacier1.html&dev=1">glaciated</a>, if <a href="/earth/climate/earth_greenhouse.html&dev=1">greenhouse</a> gas concentration was the same as today.  <a href="http://www.manchester.ac.uk/aboutus/news/display/?id=10798">Researchers</a> studying the <a href="/physical_science/physics/atom_particle/isotope.html&dev=1">isotopic</a> signatures of Earth's early atmosphere in <a href="/earth/geology/rocks_intro.html&dev=1">rocks</a> from Northern Australia have ruled out high levels of <a href="/physical_science/chemistry/nitrogen_molecular.html&dev=1">nitrogen</a> as a possible way to increase warming from <a href="/earth/Atmosphere/overview.html&dev=1">atmospheric</a> <a href="/physical_science/chemistry/carbon_dioxide.html&dev=1">carbon dioxide</a>.<p><small><em>Image courtesy of Manchester University</em></small></p>This is an artist's conception of the
  Earth and the inner and outer <a
  href="/glossary/radiation_belts.html&dev=1">radiation belts</a> that surround it. The Earth's radiation belts are just one part of
  the system called the <a
  href="/earth/Magnetosphere/overview.html&dev=1">magnetosphere</a>. The radiation belts of the Earth are made up of <a
  href="/physical_science/physics/atom_particle/electron.html&dev=1">electrons</a>,
<a
  href="/physical_science/physics/atom_particle/proton.html&dev=1">protons</a>
  and heavier atomic ions. These particles get trapped in the <a
  href="/earth/Magnetosphere/earth_magnetic_field.html&dev=1">magnetic field of the Earth</a>. 
These belts were <a
  href="/earth/Magnetosphere/radiation_belts_discovery.html&dev=1">discovered</a> by James Van Allen in 1958, and so they are known as Van Allen
  Belts.<p><small><em>Courtesy of Windows to the Universe</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">crop withering</a>. <a href="/teacher_resources/online_courses/health/events_health.html&dev=1">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">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 sinuous glowing band of <a
  href="/earth/Magnetosphere/aurora.html&dev=1">aurora</a> (the Aurora Australis
  or Southern Lights) loops around the <a
  href="/earth/polar/polar_south.html&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&dev=1">Aurora are produced</a>
  when <a
  href="/physical_science/physics/atom_particle/particle_radiation.html&dev=1">energetic particles</a>
 entering the Earth's
  atmosphere from space interact with <a
  href="/physical_science/physics/atom_particle/atom.html&dev=1">atoms</a> and <a
  href="/earth/geology/molecule.html&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>An image of Hurricane Sandy taken by the GOES-13 satellite on October 28.  This category 1 <a href="/earth/Atmosphere/hurricane/hurricane.html&dev=1">hurricane</a> was huge, spanning a horizontal distance of about one-third the US continental landmass.  The storm came onshore in New Jersey, and gradually moved northeast.  The storm disrupted the lives of tens of millions in the eastern US, doing billions of dollars in damage, resulting in over 30 deaths.  Visit the National Hurricane Center's webpage on <a href="http://www.nhc.noaa.gov/">Hurricane Sandy</a> for details.<p><small><em>Image courtesy of NASA</em></small></p>

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