OUR SOLAR SYSTEM HAS 218 MOONS

Did you know our moon is called Luna?  It is the 14th largest astronomical body in our solar system.  Which came first, Earth or Luna?  Earth.

• Luna moves in synchronicity with our planet, meaning that we always see the same side

• light takes only 1.28 seconds to get from there to here
• is just about exactly 1/50th the volume of Earth
• the remarkable coincidence of size and distance is such that the shadow of Luna just exactly covers the Sun in a solar eclipse

• the first space craft to land (it actually crashed) on the moon was the Soviet Union's Luna 2, on 13 September 1959
• the first man on Luna was Neil Armstrong in 1969
• Gene Cernan in 1972 was the last--all twelve moon walks were by American men

Just this month astronomers announced 20 new moons around Saturn, found using the Subaru telescope on Mauna Kea.  Seventeen of them are moving in retrograde, meaning opposite to Saturn's rotation.  

There is a contest to name them all.  The limitation is that they must be linked to giants from Norse, Gallic and Inuit mythology.  The deadline is December 6, 2019.  The speculation about Saturn is that the number of moons will someday exceed 100.

Here are the moons:

• Mercury and Venus:  no moon
• Earth                             1
• Mars                             2
• Jupiter                        79
• Saturn                         82
• Uranus                        27
• Neptune                      14
• Dwarf moons              13

I count 218 moons.  The astronomical field seems to offer other numbers, but this possibly has to do with what is a dwarf moon, plus, what about satellites of asteroids.  For example, in 2009 Universe Today (UT) reported 336 moons.  To the left is Luna compared to the largest moon, Ganymede of Jupiter.

Further, UT indicated that four planets in our Solar System have ring systems:  Saturn (more than 30), Jupiter (right, 4), Neptune (6) and Uranus (13).  Those digits represent number of rings.  And here you thought, all your life, that only Saturn had rings.

Interesting that several moons around Jupiter and Saturn circle their planet as swift as three times or so each day.  Andrastea (left) travels along at 67,000 miles/hour--thirty times faster than our Luna--and orbits the giant Jupiter in 7 hours 8 minutes.   Phobos around Mars makes a cycle more than three times/day.  Luna, takes 27.322 days/month.

Some noteworthy November space viewing opportunities:

• The Leonids Meteor Shower could bring as many as 15 meteors/night on November 17.
• Those bright lights after sunset are Jupiter and Venus.  On November 24 they will be in conjunction.

• Facing north, there is the W-shaped 'Iwake-li'i, or Cassiopeia.  A small fuzzy smudge about 15 degrees south of 'Iwakeli'i is Andromeda, the closest galaxy to our Milky Way, about two and a half million light years away.  This means that the light you are viewing began its journey 2.5 million years ago.  How far back in time was that?  Us, Homo sapiens, only began to appear around 0.25 million years ago!

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