A new study has found that <a href="/earth/Atmosphere/airpollution_intro.html&edu=high&dev=">pollution</a> from <a href="/earth/Atmosphere/particulates.html&edu=high&dev=">fine particles</a> in the air - mainly the result of burning coal or <a href="/earth/interior/eruptions.html&edu=high&dev=">volcanic eruptions</a> - can shade <a href="/earth/Life/cnidarian.html&edu=high&dev=">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>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=high&dev=">full phase</a>. Secondly, the <a href="/sun/sun.html&edu=high&dev=">Sun</a>, <a href="/earth/earth.html&edu=high&dev=">Earth</a> and <a href="/earth/moons_and_rings.html&edu=high&dev=">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>According to a Greek legend, the sea god Poseidon placed the figure of <a href="/the_universe/Constellations/circumpolar/cassiopeia.html&edu=high&dev=">Cassiopeia</a> among the stars. It is said that Cassiopeia has a ridiculous upside-down position to punish her for having been pretentious.<p><small><em>Image courtesy of 1995 Visual Language (c). All rights reserved.</em></small></p>Anti-crepuscular rays are beams of sunlight that appear to converge on a point opposite the sun. They are similar to crepuscular rays, but are seen opposite the sun in the sky. Anti-crepuscular rays are most frequently visible near sunrise or sunset. This photo of anti-crepuscular rays was taken at sunset in Boulder, Colorado. Crepuscular rays are usually much brighter than anti-crepuscular rays.<p><small><em> Image Courtesy of Carlye Calvin</em></small></p><p>You don't normally see <a href="/space_weather/space_weather.html&edu=high&dev=">space weather</a> forecasted on the evening news, but it does impact life on <a href="/earth/earth.html&edu=high&dev=">Earth</a> in many ways. What are the threats posed from all of these natural disasters and how can we work to mitigate those threats beforehand? </p>
<p>Check out the materials about natural disasters in <a href="/earth/natural_hazards/when_nature_strikes.html&edu=high&dev=">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>According to <a href="http://www.jpl.nasa.gov/news/news.php?release=2013-277">NASA scientists</a>, the Voyager 1 spacecraft entered interstellar space in August 2012, becoming the first spacecraft to leave the <a href="/our_solar_system/solar_system.html&edu=high&dev=">solar system</a>. The space probe is about 19 billion km from the <a href="/sun/sun.html&edu=high&dev=">Sun</a>.  <a href="/space_missions/voyager.html&edu=high&dev=">Voyager 1 and 2</a> were launched in 1977 on a <a href="/space_missions/voyager.html&edu=high&dev=">mission</a> that flew them both by <a href="/jupiter/jupiter.html&edu=high&dev=">Jupiter</a> and <a href="/saturn/saturn.html&edu=high&dev=">Saturn</a>, with Voyager 2 continuing to <a href="/uranus/uranus.html&edu=high&dev=">Uranus</a> and <a href="/neptune/neptune.html&edu=high&dev=">Neptune</a>. Voyager 2 is the longest continuously operated spacecraft. It is about 15 billion km away from the <a href="/sun/sun.html&edu=high&dev=">Sun</a>.<p><small><em>Image courtesy of NASA</em></small></p>

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