Starry Skies Above Santa Monica

September 12-19, 2000

Mirek Plavec
Emeritus Professor of Astronomy,
UCLA

   When and Where to See the Planets
   Just one planet is available for a comfortable evening watching. Consider the situation on Saturday night, September 15. The Sun will set just about 7 p.m., and about an hour later, the background sky will be sufficiently dark for you to find the brightest stars. Actually, the brightest “star” this time will be the planet Mars. You will find it fairly high in the sky above the south -– or, if you look later (say about 10 p.m.), the reddish planet will shine for you in the south-west. Mars will set there shortly after midnight.
   The next planet to look for will be Saturn, which rises at 11 p.m. on the opposite side of the sky, in the northeast. Saturn, shining as a good first-magnitude star, forms a nice pair with Aldebaran, the “red eye of the Bull” (Taurus). Aldebaran precedes Saturn, since it is located to the southwest of the planet (but not far from it).
   Gradually, the winter constellations will emerge, and will be dominated by the visiting planet, Jupiter. Jupiter, in the middle of the constellation Gemini (the Celestial Twins), rises shortly before 1 a.m. Once Jupiter appears above the eastern horizon, it will dominate the sky for several night hours, being even brighter than the apparently brightest true star in the sky, Sirius. Sirius lies much farther to the south from Jupiter, and, as a consequence, it rises later, at about 3 a.m. By that time, the bright winter constellations like Orion, Taurus, Gemini, and Auriga, are already all visible above the eastern horizon.
   When the beauty of these stars is about to fade as the Sun begins to illuminate the upper layers of our atmosphere above our heads, the brilliant Venus appears above the eastern horizon, after 4 a.m.
   With the winter constellations, the Moon appears. It was in its Last Quarter on September 10, passed by Jupiter on September 12, and meets Venus in the morning hours of Saturday, September 15. This is not a very close encounter, the Moon will pass fairly high above Venus, but even so, such an encounter is always a beautiful sight. By this time, the Moon will be only a thin crescent, since two days later, it will be New and therefore invisible.

   Look towards the Center of our Galaxy!
   The fading Moon will not interfere with your star watching in the evening. If you are lucky enough to be somewhere away from the city lights, you will be able to enjoy the full beauty of the Milky Way. Its silvery band, formed by millions of distant stars, runs across the entire sky from the south-west to the north-east, through the constellations of Scorpius, Sagittarius, Aquila (the Eagle), Cygnus (the Swan), Cepheus, Cassiopeia, and disappears in Perseus, in the north-east.
   Even if you cannot escape the city lights completely, try to look at the stars from above the beach. The Milky Way will probably lose most of its gentle beauty, but you may still see its brighter spots. And our map will help you identify two important constellations, Scorpius (the Scorpion) and Sagittarius. The latter name is usually translated as “the Archer” but this translation tells you just only half of the truth, because in traditional ancient sky maps, the upper half of Sagittarius is really a man holding a bow, but the lower half belongs to a horse. If you can see this creature in the stars, you have my admiration. What I can see is a teapot, while Scorpius fits its name much better.
   Between these two constellations lies the center of our Galaxy. In our map, it is marked by “GC” and a cross. Planet Mars, by far the brightest object in that region, will help you identify the stars, especially the first magnitude reddish “competitor of Mars,” Antares in Scorpius, to the west of Mars.
   Even if you used the biggest telescope, you would not be able to see the center of our stellar system, the Galaxy. It is very far from us, some 28,000 light years. Yet that is not the worst obstacle: that region is so rich in stars -– even in those extremely bright ones, that it would be a spectacular sight –- were it not for extremely dense clouds of interstellar dust that lie between us and the center. Observing far from city lights, you will see just these dark clouds as they split the otherwise luminous band of the Milky Way.