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Our Solar System

Our solar system is filled with a wide assortment of celestial bodies - the Sun itself, our eight planets, dwarf planets, and asteroids - and on Earth, life itself! The inner solar system is occasionally visited by comets that loop in from the outer reaches of the solar system on highly elliptical orbits. In the outer reaches of the solar system, we find the Kuiper Belt and the Oort cloud. Still farther out, we eventually reach the limits of the heliosphere, where the outer reaches of the solar system interact with interstellar space. Solar system formation began billions of years ago, when gases and dust began to come together to form the Sun, planets, and other bodies of the solar system.

A near-Earth <a href="/our_solar_system/asteroids.html&dev=1">asteroid</a> - named 2012 DA14 by astronomers – passed within 17,200 miles from Earth on February 15, 2013. On closest approach at about 1:25 p.m. CST on February 15, although it was within the orbit of the <a href="/earth/moons_and_rings.html&dev=1">Moon</a> and even geosynchronous <a href="/space_missions/satellites.html&dev=1">satellites</a>, it didn't strike Earth!  Find out more from <a href="http://www.nasa.gov/mission_pages/asteroids/news/asteroid20130201315144.html">NASA</a>! Fragments of a meteorite hit Chelyabinsk, Russia on 2/15/2013 <a href="http://www.reuters.com/article/2013/02/15/us-russia-meteorite-idUSBRE91E05Z20130215">injuring over 500</a>. Learn about <a href="http://www.windows2universe.org/our_solar_system/meteors/meteors.html">meteors and meteorites</a>.<p><small><em>NASA/JPL-CalTech</em></small></p>Neptune's <a href="/neptune/lower_atmosphere.html&dev=1">atmosphere</a> shows
a striped pattern of
<a href="/neptune/atmosphere/N_clouds_overview.html&dev=1">clouds</a>.
This cloud pattern is very similar to that of
<a href="/jupiter/jupiter.html&dev=1">Jupiter</a> and
<a href="/saturn/saturn.html&dev=1">Saturn</a>.
Neptune even has a <a href="/neptune/atmosphere/N_clouds_GDS.html&dev=1">Great Dark
Spot</a> similar
to Jupiter's <a href="/jupiter/atmosphere/J_clouds_GRS.html&dev=1">Great
Red Spot</a>.
The Great Dark Spot of Neptune is thought to be a hole, similar to the hole
in the <a href="/earth/Atmosphere/ozone_layer.html&dev=1">ozone layer on
Earth</a>,
in the <a href="/physical_science/chemistry/methane.html&dev=1">methane</a> cloud
deck of Neptune.<p><small><em>Image courtesy of NASA</em></small></p>This historic image is the first ever taken from a spacecraft in orbit about <a href="/mercury/mercury.html&dev=1">Mercury</a>, the innermost planet of the solar system.  Taken on 3/29/2011 by <a href="/space_missions/robotic/messenger/messenger.html&dev=1">MESSENGER</a>, it shows numerous craters across the <a href="/mercury/Interior_Surface/Surface/surface_overview.html&dev=1">surface</a> of the planet.  Temperatures there can reach over 800°F because Mercury is so close to the Sun and rotates so slowly.  MESSENGER entered orbit around Mercury earlier in March 2011.<p><small><em>NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington</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&dev=1">full phase</a>. Secondly, the <a href="/sun/sun.html&dev=1">Sun</a>, <a href="/earth/earth.html&dev=1">Earth</a> and <a href="/earth/moons_and_rings.html&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>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&dev=1">solar system</a>. The space probe is about 19 billion km from the <a href="/sun/sun.html&dev=1">Sun</a>.  <a href="/space_missions/voyager.html&dev=1">Voyager 1 and 2</a> were launched in 1977 on a <a href="/space_missions/voyager.html&dev=1">mission</a> that flew them both by <a href="/jupiter/jupiter.html&dev=1">Jupiter</a> and <a href="/saturn/saturn.html&dev=1">Saturn</a>, with Voyager 2 continuing to <a href="/uranus/uranus.html&dev=1">Uranus</a> and <a href="/neptune/neptune.html&dev=1">Neptune</a>. Voyager 2 is the longest continuously operated spacecraft. It is about 15 billion km away from the <a href="/sun/sun.html&dev=1">Sun</a>.<p><small><em>Image courtesy of NASA</em></small></p>Comets are <a href="/comets/comet_nucleus.html&dev=1">lumps</a> of ice
and dust that periodically come into the center of the solar system from
its <a href="/comets/Oort_cloud.html&dev=1">outer
reaches</a>.
Some comets make <a href="/comets/perihelion_pass.html&dev=1">repeated
trips</a> to the inner
solar system. When comets get close enough to the Sun, heat
makes them start to <a href="/comets/sublimation.html&dev=1">evaporate</a>.
Jets of gas and dust form long
<a href="/comets/tail.html&dev=1">tails</a> that we can see from
Earth. 
This photograph shows <a href="/comets/comets_table.html&dev=1">Comet
Kohoutek</a>,
which visited the inner solar system in 1973.  It has an
<a href="/physical_science/physics/mechanics/orbit/orbit_shape_interactive.html&dev=1">orbit</a> of
about 75,000 years!<p><small><em>Image courtesy of NASA</em></small></p>

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA