Starry Skies Above Santa Monica

August 29 - September 4, 2002

Mirek Plavec
Emeritus Professor of Astronomy,
UCLA

   Venus - Still Our Evening Star
   Venus reached its “greatest elongation east” on August 21, and since then it appears to us to be moving back to the Sun in the western sky. For now, this apparent motion is still rather slow, and Venus remains quite conspicuous in the western sky after sunset. The Sun sets shortly before 7:20 p.m., and Venus sets a few minutes after 9 p.m. Thus, it still adorns our early evening sky, and you can spot it easily above the western horizon – and you can start looking for it about half an hour after sunset.
   The Sun is still projected into the constellation of Leo (the Lion), and Venus travels through the next constellation of the zodiac, Virgo. You should have quite an interesting view if you look on the evening of Saturday, August 31. Venus will shine very close to the first-magnitude star Spica, the brightest star in Virgo. For several evenings, the two will remain fairly close together. Since Spica is significantly fainter than Venus, it will be necessary to wait till the western sky loses most of its glare due to the Sun; then, of course, both objects will be quite close to the southwestern horizon, so you must be sure to have a clear view all the way down to the horizon. Fortunately, Santa Monica offers perfect places at and above the seashore!

   Two Morning Planets
   Mars is invisible, too close to the Sun, and Mercury is also not suitably placed for easy viewing. The two other bright planets, Jupiter and Saturn, come up after midnight. Saturn rises shortly before 1 a.m., and Jupiter follows three hours later, shortly before 4 a.m. Jupiter is projected into the constellation of Cancer, the Crab, where there are no bright stars – although Jupiter would dominate even if there were first-magnitude stars around. After Venus, Jupiter is the brightest star-like object in the sky.
   The position of Saturn is rather peculiar: it is currently projected into the constellation of Orion! If you believe in astrology, and think that the location of the planets in the zodiac plays any role in your life, then this is rather a confusing position, since Orion does not belong among the traditional constellations of the zodiac.
   Two traditions are clashing here. According to one, the annual path of the Sun (the ecliptic) is divided into twelve “domes” or “signs,” and Orion is not among them, since the ecliptic passes above Orion, from Taurus (the Bull) into Gemini (the Celestial Twins).
   The main planets follow this path fairly faithfully, but not exactly, since their orbital planes are tilted a bit to the ecliptic. For Saturn, the inclination is only 2.5 degrees, so one would expect to see Saturn always projected among the constellations of the zodiac, if it were not for the traditional boundaries of the constellations.
   The other tradition depicts the constellations in the way the ancient Greeks plotted them. According to this tradition, Orion is a superhuman giant, who stands there in the sky, holding a club in his hand, as he defends himself against the furious Bull (Taurus). And it is this club that extends fairly high up above the body of Orion, and reaches almost to the ecliptic between Taurus and Gemini.
   Orion’s club does not reach quite to the ecliptic, but, as I said, Saturn can deviate as much as 2.5 degrees away from the ecliptic. In our case, Saturn is located below the ecliptic, and therefore it is temporarily projected into Orion!
   The Moon will pass near Saturn in the morning hours of September 1, and then travel above Jupiter on September 4.

   The Moon
   – Coming Up Later and Later
   We had the Full Moon on August 22. On that evening, the Moon was rising at about the time of the sunset. On each following night, the Moon rises, on the average, about 50 minutes later, so it is not surprising that in this coming week, the Moon will shine mostly after midnight. Its Last Quarter occurs in the night of August 30/31, when the Moon is projected fairly close to Aldebaran, “the red eye of the Bull (Taurus).” On that night, the Moon will rise close to midnight, and after that, it will be a morning object.
   As the bright segment of the Moon’s face shrinks into a still narrower crescent, the Moon will be moving eastward (and also to the south) among the constellations, through Gemini, Cancer, and Leo The New Moon comes on the evening of September 6, Friday. If we could see it, it would be projected close to the Sun in Virgo, but it will miss the disk of the Sun, and there will be no eclipse.

   The (Real) Evening Stars
   These evenings are usually fairly warm, the Moon is gone, and if you avoid city lights, you can easily spot the brightest stars above you. Let’s say that you look at about 9 p.m. Virtually above your head is the bright bluish star Vega in Lyra. To the south is Altair, and to the east or north-east of Vega is Deneb. These three stars form the famous “Summer Triangle.” About to set in the south-west is the red supergiant Antares, and above the west shines the orange-colored giant Arcturus.