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The Winter 2010 issue of The Earth Scientist includes a variety of educational resources, ranging from astronomy to glaciers. Check out the other publications and classroom materials in our online store.

Poles in Space

The areas around the North and South Poles of planets, moons, and even the Sun are often interesting and unusual places. We have discovered all sorts of unique behavior at these locations, while on some planets, the characteristics of the poles are similar to those of Earth. On some planets and moons, we still don't have observations from their poles so can only make educated guesses of what we expect to find there based on our scientific understanding of the celestial body. The links below provide an overview of what we know about the polar regions of many of the major bodies in the solar system. An important concept related to the poles of the planets is the amount of tilt of a planet's rotational axis relative to the plane of the ecliptic - the orbital plane in which the planets orbit the Sun. Planets with a large tilt have stronger seasonal behavior than planets without a tilt.
This image, made with <a href="/earth/Atmosphere/tornado/radar.html&edu=high">radar</a> data, shows the area around the <a href="/mercury/mercury_polar_regions.html&edu=high">North Pole of Mercury</a>. There are some white circles or "doughnuts" in the picture. The white circles might be ice at the bottom of <a href="/mercury/mercury_polar_regions.html&edu=high">meteor craters</a>. The picture is a few hundred kilometers across. It was made by the Arecibo radio telescope in Puerto Rico.<p><small><em>Image courtesy of NAIC - Arecibo Observatory, a facility of the NSF (J. Harmon, P. Perrilat, and M. Slade).</em></small></p>A sinuous glowing band of <a
  href="/earth/Magnetosphere/aurora.html&edu=high">aurora</a> (the Aurora Australis
  or Southern Lights) loops around the <a
  href="/earth/polar/polar_south.html&edu=high">southern polar</a>
region in the
  distance as viewed by astronauts onboard the space shuttle on <a
  href="/earth/Magnetosphere/aurora/aurora_colors.html&edu=high">Aurora are produced</a>
  when <a
  href="/physical_science/physics/atom_particle/particle_radiation.html&edu=high">energetic particles</a>
 entering the Earth's
  atmosphere from space interact with <a
  href="/physical_science/physics/atom_particle/atom.html&edu=high">atoms</a> and <a
  href="/earth/geology/molecule.html&edu=high">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>This is a picture of the ice cap at the <a href="/mars/places/mars_south_polar_region.html&edu=high">South Pole on Mars</a>. This picture was shot from Mars orbit in 2000 by a spacecraft called <a href="/mars/exploring/MSG_overview.html&edu=high">Mars Global Surveyor</a>. The white regions are ice. Most of the ice is water ice, but there is also a thinner layer of dry ice (frozen carbon dioxide) on top of the water ice. The ice cap is about 420 km (260 miles) across.<p><small><em>Image courtesy of NASA/JPL/Malin Space Science Systems.</em></small></p>Jupiter has <a href="/jupiter/magnetosphere/jupiter_aurora.html&edu=high">aurora at its poles</a>, as do several other planets that have magnetic fields.  The aurora at Jupiter has a very interesting interaction with its moon, <a href="/jupiter/moons/io.html&edu=high">Io</a>.  Io's <a href="/earth/interior/volcanos_general.html&edu=high">volcanoes</a> release lots of sulfur into a <a href="/jupiter/magnetosphere/Io_torus.html&edu=high">torus</a> around Jupiter, which is embedded in Jupiter's <a href="/jupiter/upper_atmosphere.html&edu=high">magnetic field</a>.  Particles from this torus travel along Jupiter's magnetic field lines to the poles of Jupiter, causing <a href="/jupiter/magnetosphere/jupiter_aurora.html&edu=high">auroral lights</a>.<p><small><em>Image courtesy of J. Clarke (University of Michigan) and NASA/ESA Hubble Space Telescope (November 26, 1998).</em></small></p>Astronomers have discovered a bizarre, <a href="/saturn/atmosphere/polar_hexagon.html&edu=high">hexagon-shaped feature</a> in the <a href="/saturn/atmosphere/S_clouds_overview.html&edu=high">clouds of Saturn</a> near the planet's <a href="/saturn/saturn_polar_regions.html&edu=high">North Pole</a>. The feature was first seen in images returned by the <a href="/space_missions/voyager.html&edu=high">Voyager spacecraft</a> in the 1980s. The <a href="/missions/cassini.html&edu=high">Cassini spacecraft</a> took this infrared image of the hexagon in 2006.  Scientists think the feature is some sort of wave in <a href="/saturn/lower_atmosphere.html&edu=high">Saturn's atmosphere</a> about 75 kilometers beneath the planet's visible cloud tops.<p><small><em>Image courtesy NASA/JPL/University of Arizona</em></small></p>New observations by the MESSENGER spacecraft provide  support for the hypothesis that Mercury harbors abundant water ice and other frozen volatile materials in its permanently shadowed (shown in red) polar craters. Areas where polar deposits of ice imaged by Earth-based radar are shown in yellow.<p><small><em>Image courtesy of NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/National Astronomy and Ionosphere Center, Arecibo Observatory</em></small></p>

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