Monday is Guam's Liberation Day and Liberation Day always heralds an incredible week of space anniversaries.  Thirty-nine years ago, a human walked on a new world for the first time.  On 20 July 1969, Neil Armstrong took one giant step for the human race.  Also, 32 years ago on the same date, the Viking 1 lander touched down on Mars and began transmitting our first surface pictures of the red planet.  Fourteen years ago this week, Jupiter was being pounded by the impacts of Comet Shoemaker-Levy 9 and 58 years ago this Thursday the first rocket was launched from what has become the world’s busiest spaceport, Cape Canaveral.  Quite an impressive week in space history!

We have three evening planets, brilliant Jupiter in the east and Mars and Saturn near the western horizon at one hour after sunset.  Of course, if you watch the sunset this week, you may notice an airplane landing at the airport.  But if you watch it for a while, you’ll discover that although it gets slowly closer to the horizon, it never lands.  That bright beacon isn’t a star; it’s Venus and if you’re patient, around 7:30 this week, you can see four of the planets.

After you find Mars, Saturn and Venus in the western sky, turn 90° to your right and find the Little Dipper.  July is virtually the only month you can easily see the Little Dipper from Guam because it balances upright on Polaris the North Star, the end star of the Little Dipper’s handle.  

July is also the best month to see another dim constellation in the northern sky.  First, find the Little Dipper and then look up and to the right.  You should see a small triangle of stars above and about midway between the Little Dipper’s bowl and the bright star Deneb.  That triangle is the head of a fearsome beast; Draco the Dragon.  The dragon’s body loops down to the right side of the Little Dipper and then arches over it to end between the Little Dipper and the Big Dipper in the west.  If you use the end stars of the Little Dipper's bowl as pointers, they’ll point you to a star in the Dragon’s tail.  That’s Thuban, the pole star of the ancient Egyptians.

The Earth very slowly wobbles as it spins and the Earth's spin axis makes a giant circle in the sky.  The circle takes 26,000 years to complete so don't expect much change in your lifetime.  Polaris has been near the northern spin axis for about 700 years and will be as close the spin axis point as it will get in 2102.  About 6,000 years ago, the spin axis point was near Thuban, that star in the Dragon's tail.  The main passage in the Great Pyramid of Cheops is aligned to point to Thuban.

About 13.000 years from now, the bright star Vega will be the North Star though Vega will never be as close to the spin point as Polaris and Thuban.  Vega is that bright star high in the northeast and if you find Polaris, Thuban and Vega, you get an idea of just how much the Earth wobbles as it spins.

There is no South Pole star right now, but as the spin axis precesses, several stars will take their place as the South Pole star over the next 26 millennia.  None of them are as bright as Polaris and Vega however.  The other planets have pole stars too.  The north pole of Uranus points to a star in Ophiucus the Serpent Bearer called Sabik that's almost as bright as Polaris.  See if you can find four planets, Polaris, a dragon and the pole star of the Egyptians tonight. 
 

Would you like to be on the Planetarium e-mail list and receive a monthly reminder of the Planetarium shows and occasional notices of cool things in the sky?  Just send an e-mail to stars@guam.net requesting that you be added and I'll put you on the list!

Don't forget that you can hear this information on Guam's public radio station KPRG, 89.3 on your radio dial.  The program is called Tropical Skies and it airs twice on Monday, during the noon hour at 12:25 and at 6:01 in the evening.  Support your public radio station

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