If you’ve not seen Jupiter yet, just go out on Thursday the 17th and look for the almost full Moon in the eastern sky.  That very bright ‘star’ next to it isn’t a star; that’s the King of the Planets, Jupiter.  Then turn around and face west and you’ll see Mars and Saturn above Regulus, the brightest star in Leo the Lion.  Mars and Saturn will be two fist-widths above the western horizon at 8:00 p.m.

Now let’s do a little stargazing.  Just turn 90 degrees to your left and face south.  Summer is well underway and the Southern Cross is beginning to tilt dramatically sideways.  By the first of August, it will disappear below the southwestern horizon to return to our early evening skies next spring.  To the left of the Cross are two bright stars that look like eyes at this time of year.  One of them, the left one, is famous.  That's Alpha Centauri, the closest star to the Sun.  

To the left of and below Alpha and Beta Centauri is a bright and totally unfamiliar constellation.  Look for an almost equilateral triangle of bright stars.  The top points up like a pyramid, and the left star of the base is the brightest.  Given the shape of the three stars, it should come as no surprise that the triangle is called Triangulum Australe the Southern Triangle.  It's much brighter than Triangulum the Triangle in the northern sky.  Triangulum Australe was first described by a man with a familiar name, Amerigo Vespucci, the man who had the Americas named after him.  The brightest star of the triangle is a red giant and its name is Atria.

Now measure five fist-widths to the left along the horizon from the triangle and then about two fist-widths up.  That bright star isn’t a star; it’s the planet Jupiter, and you can see three of the five visible planets in the early evening sky.

After you find Jupiter, turn all the way around and face east, opposite where the Sun went down.  If there aren’t too many clouds, you’ll see a much larger triangle of bright stars to your left.  The upper one will be the brightest, that’s Vega, the fifth brightest star.  The two closer to the horizon are Altair, almost due east and Deneb, farther toward the north.  These three stars form the Summer Triangle.  Vega is the brightest star of the constellation Lyra the Lyre, a very small and dim constellation that looks like a small parallelogram of stars.  Altair is the brightest star of the constellation Aquila the Eagle and it has two companion stars that are dimmer.  The three vaguely resemble Orion’s belt, and Altair and its companions are very important stars for traditional Micronesian navigation.

Deneb, the third star of the triangle, is in the constellation Cygnus the Swan and if I tell you that Deneb means ‘tail’ you’ll probably figure out what part of the constellation it is.  If you find Deneb, you should see a line of stars that extend toward the south and slightly upward.  The line should point toward the middle of a line drawn between Vega and Altair.  That’s the Swan’s body.  The large wings are at right angles to the body and closer to Deneb than to Alberio, the Swan’s head star.  The ends of both wings are bent slightly backward, just like a real swan’s wings.  The swan flies eternally south along the Milky Way.  See if you can find the triangles and their constellations 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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