<story><title>Hurricane on Saturn</title><url>http://www.nasa.gov/mission_pages/cassini/multimedia/pia14944.html</url></story><parent_chain><item><author>btilly</author><text>A random note for those who might wonder what &quot;N&quot; and &quot;S&quot; mean on another planet.&lt;p&gt;Take your right hand out.  Stick your thumb up.  Curl your fingers around.  Your thumb represents a planet&apos;s N pole, and your fingers point in the direction that the planet is spinning.  (The Earth moves from W to E, and the result is that it looks like the Sun rises in the E.  Sit down a globe and a flashlight if this comment makes no sense.)&lt;p&gt;For any spinning thing we can do the same exercise.  Just wrap your fingers of your right hand around in the direction of the spin, stick your thumb up, and that is the North pole of that spin.&lt;p&gt;Now for the fun fact.  Most of the stuff in the Solar System rotates roughly the same way.  It doesn&apos;t matter whether you take the rotation of the Earth, the rotation of the Moon, the orbit of the Moon around the Earth, the orbit of the Earth around the Sun, the orbit of Saturn around the Sun, the rotation of Saturn, the orbits of Saturn&apos;s moons around Saturn - the north poles of all of these are reasonably well aligned.&lt;p&gt;They are not exactly aligned.  For instance the Earth&apos;s rotational axis is tilted 23.5 degrees from the axis of its orbit around the Sun.  (Hence our seasons.)  And not everything follows the rule.  Uranus is the best-known exception.  But most of it lines up fairly well.&lt;p&gt;The only actual use that I&apos;ve ever found for this fact is being able to explain to my son why the Moon rises later every night, but I&apos;ve always thought that it was pretty cool.&lt;p&gt;&lt;i&gt;EDIT:&lt;/i&gt; glurgh below corrected my understanding.  It happens that for most of the planets, North corresponds to the right hand rule as I described.  But that&apos;s not actually the way it is defined and Venus in particular does not work that way.</text></item></parent_chain><comment><author>glurgh</author><text>This is only for minor bodies, not planets. The poles of planets are pretty much defined to be &apos;pointed the same way as the Earth&apos;s&apos;. The north pole of Venus is roughly aligned with the north pole of the Earth despite the fact that Venus&apos;s rotation is retrograde.&lt;p&gt;See&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Poles_of_astronomical_bodies&quot; rel=&quot;nofollow&quot;&gt;http://en.wikipedia.org/wiki/Poles_of_astronomical_bodies&lt;/a&gt;</text></comment>
<story><title>Hurricane on Saturn</title><url>http://www.nasa.gov/mission_pages/cassini/multimedia/pia14944.html</url></story><parent_chain><item><author>btilly</author><text>A random note for those who might wonder what &quot;N&quot; and &quot;S&quot; mean on another planet.&lt;p&gt;Take your right hand out.  Stick your thumb up.  Curl your fingers around.  Your thumb represents a planet&apos;s N pole, and your fingers point in the direction that the planet is spinning.  (The Earth moves from W to E, and the result is that it looks like the Sun rises in the E.  Sit down a globe and a flashlight if this comment makes no sense.)&lt;p&gt;For any spinning thing we can do the same exercise.  Just wrap your fingers of your right hand around in the direction of the spin, stick your thumb up, and that is the North pole of that spin.&lt;p&gt;Now for the fun fact.  Most of the stuff in the Solar System rotates roughly the same way.  It doesn&apos;t matter whether you take the rotation of the Earth, the rotation of the Moon, the orbit of the Moon around the Earth, the orbit of the Earth around the Sun, the orbit of Saturn around the Sun, the rotation of Saturn, the orbits of Saturn&apos;s moons around Saturn - the north poles of all of these are reasonably well aligned.&lt;p&gt;They are not exactly aligned.  For instance the Earth&apos;s rotational axis is tilted 23.5 degrees from the axis of its orbit around the Sun.  (Hence our seasons.)  And not everything follows the rule.  Uranus is the best-known exception.  But most of it lines up fairly well.&lt;p&gt;The only actual use that I&apos;ve ever found for this fact is being able to explain to my son why the Moon rises later every night, but I&apos;ve always thought that it was pretty cool.&lt;p&gt;&lt;i&gt;EDIT:&lt;/i&gt; glurgh below corrected my understanding.  It happens that for most of the planets, North corresponds to the right hand rule as I described.  But that&apos;s not actually the way it is defined and Venus in particular does not work that way.</text></item></parent_chain><comment><author>cefarix</author><text>Good ol&apos; cross-product and angular momentum!</text></comment>