Stars don't last forever. Occasionally, a star bigger than our Sun will end its life in a huge explosion, called a <a href="/the_universe/supernova.html&edu=high&dev=1/k=/teacher_resources/moons/=/earth/windows.html">supernova</a>. The center of the star collapses in less than a second, blowing away the outer layers of the star. There are many beautiful images of supernova remnants, the expanding shell of gas made up of the outer layers of the original star. This image is the Vela Supernova Remnant.<p><small><em>Image courtesy of the Anglo-Australian Observatory/Royal Observatory Edinburgh</em></small></p>The spinning vortex of <a href="https://www.windows2universe.org/saturn/saturn.html">Saturn</a>'s north polar storm resembles a giant deep red rose surrounded by green foliage in this false-color <a href="http://www.nasa.gov/mission_pages/cassini/multimedia/pia14944.html">image</a> from NASA's <a href="https://www.windows2universe.org/missions/cassini.html">Cassini spacecraft</a>. The eye is 2,000 kilometers across with cloud speeds as fast as 150 meters per second. It is not known how long this newly discovered north-polar <a href="https://www.windows2universe.org/earth/Atmosphere/hurricane/hurricane.html">hurricane</a> has been active. The view was acquired at a distance of approximately 419,000 kilometers from Saturn.<p><small><em>NASA/JPL-Caltech/SSI</em></small></p>There are over 900 <a href="/the_universe/uts/megalith.html&edu=high&dev=1/k=/teacher_resources/moons/=/earth/windows.html">rings of stone</a> located in the British Isles. The most famous of these stone rings is of course, <a href="/the_universe/uts/stonehenge.html&edu=high&dev=1/k=/teacher_resources/moons/=/earth/windows.html">Stonehenge</a>. The stones of Stonehenge were put in place between 3,000 B.C and 2,000 B.C. by neolithic people.Some speculate that the site was built as a temple of worship of the ancient Earth deities. Some say it was used as an <a href="/the_universe/uts/stonehenge_astro.html&edu=high&dev=1/k=/teacher_resources/moons/=/earth/windows.html">astronomical observatory</a> of sorts. Still others say it was a burial ground.<p><small><em> Image courtesy of Corel Photography.</em></small></p>The <a href="http://www.windows2universe.org/earth/Atmosphere/tornado/fujita.html">EF-5</a> <a href="http://www.windows2universe.org/earth/Atmosphere/tornado.html">tornado</a> that hit El Reno, Oklahoma on May 31st, 2013 was the widest ever recorded in the US, according to the National Weather Service in Norman Oklahoma. The tornado, which remained on the ground for 40 minutes and reached 2.6 miles across (4.2 km), took the lives of 18 people including storm chasers Tim Samaras, Paul Samaras and Carl Young.<p><small><em>Image courtesy of National Weather Service, Norman Oklahoma</em></small></p>A new study has found that <a href="/earth/Atmosphere/airpollution_intro.html&edu=high&dev=1/k=/teacher_resources/moons/=/earth/windows.html">pollution</a> from <a href="/earth/Atmosphere/particulates.html&edu=high&dev=1/k=/teacher_resources/moons/=/earth/windows.html">fine particles</a> in the air - mainly the result of burning coal or <a href="/earth/interior/eruptions.html&edu=high&dev=1/k=/teacher_resources/moons/=/earth/windows.html">volcanic eruptions</a> - can shade <a href="/earth/Life/cnidarian.html&edu=high&dev=1/k=/teacher_resources/moons/=/earth/windows.html">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>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>


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