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&edu=high&dev=1/earth/Atmosphere/moons/h/neptune/cloudart_present.ppsx">methane</a>, a powerful <a href="/earth/climate/cli_greengas.html&edu=high&dev=1/earth/Atmosphere/moons/h/neptune/cloudart_present.ppsx">greenhouse gas</a>.
Watch the NBC Learn video - <a href="/earth/changing_planet/permafrost_methane_intro.html&edu=high&dev=1/earth/Atmosphere/moons/h/neptune/cloudart_present.ppsx">Thawing Permafrost and Methane</a> to find out more.<p><small><em>Image courtesy of the    USGS</em></small></p>This image is a montage of high resolutions photographs of the Earth taken in January 2012 by the Visible/Infrared Imager Radiometer Suite (VIIRS) instrument on the Suomi NPP satellite.  The image shows many stunning details of <a href="http://www.windows2universe.org/earth/earth.html">our home planet</a> - <a href="http://solarsystem.nasa.gov/multimedia/gallery/VIIRS_4Jan2012.jpg">particularly at high resolution</a>. The beauty of our planet is obvious from space - our blue <a href="http://www.windows2universe.org/earth/Water/overview.html">waters</a>, our white <a href="http://www.windows2universe.org/earth/Atmosphere/cloud.html">clouds</a>, and the green from <a href="http://www.windows2universe.org/earth/Life/life.html">life</a> abundant at the surface.<p><small><em>Image courtesy of NASA</em></small></p>This is an artist's conception of the
  Earth and the inner and outer <a
  href="/glossary/radiation_belts.html&edu=high&dev=1/earth/Atmosphere/moons/h/neptune/cloudart_present.ppsx">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&edu=high&dev=1/earth/Atmosphere/moons/h/neptune/cloudart_present.ppsx">magnetosphere</a>. The radiation belts of the Earth are made up of <a
  href="/physical_science/physics/atom_particle/electron.html&edu=high&dev=1/earth/Atmosphere/moons/h/neptune/cloudart_present.ppsx">electrons</a>,
<a
  href="/physical_science/physics/atom_particle/proton.html&edu=high&dev=1/earth/Atmosphere/moons/h/neptune/cloudart_present.ppsx">protons</a>
  and heavier atomic ions. These particles get trapped in the <a
  href="/earth/Magnetosphere/earth_magnetic_field.html&edu=high&dev=1/earth/Atmosphere/moons/h/neptune/cloudart_present.ppsx">magnetic field of the Earth</a>. 
These belts were <a
  href="/earth/Magnetosphere/radiation_belts_discovery.html&edu=high&dev=1/earth/Atmosphere/moons/h/neptune/cloudart_present.ppsx">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>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>Scientists at the University of Michigan have found that <a href="/earth/polar/cryosphere_permafrost1.html&edu=high&dev=1/earth/Atmosphere/moons/h/neptune/cloudart_present.ppsx">permafrost</a> in the <a href="/earth/polar/polar_north.html&edu=high&dev=1/earth/Atmosphere/moons/h/neptune/cloudart_present.ppsx">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&edu=high&dev=1/earth/Atmosphere/moons/h/neptune/cloudart_present.ppsx">climate-warming</a> <a href="/physical_science/chemistry/carbon_dioxide.html&edu=high&dev=1/earth/Atmosphere/moons/h/neptune/cloudart_present.ppsx">carbon dioxide</a>, to the <a href="/earth/Atmosphere/overview.html&edu=high&dev=1/earth/Atmosphere/moons/h/neptune/cloudart_present.ppsx">atmosphere</a> much faster than previously thought.<p><small><em>George Kling, The University of Michigan</em></small></p><p>Something on Earth is always burning! NASA's Earth Observatory tracks wildfires across the world with <a href="http://earthobservatory.nasa.gov/GlobalMaps/view.php?d1=MOD14A1_M_FIRE" target="_blank">maps available for viewing</a> from 2000-present. Some wildfires can restore <a href="/earth/ecosystems.html&edu=high&dev=1/earth/Atmosphere/moons/h/neptune/cloudart_present.ppsx">ecosystems</a> to good health, but many can threaten human populations, posing a natural disaster threat.</p>
<p>Check out the materials about natural disasters in <a href="/earth/natural_hazards/when_nature_strikes.html&edu=high&dev=1/earth/Atmosphere/moons/h/neptune/cloudart_present.ppsx">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>

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