Starry Skies Above Santa Monica
January 5-11, 2000

Mirek Plavec

Emeritus Professor of Astronomy, UCLA

   The Moon and Planets
   The New Moon is coming on Thursday, January 6. On the following evenings, you will see the growing crescent of the Moon after sunset. In the early evening of Monday, January 10, the (still fairly thin) crescent will pass close below the planet Mars. Mars is by no means spectacular, but it still shines as a star of the first magnitude, and is without competition in that region of the sky, so you can find it easily on any evening. On Monday, the Moon will assist. During the following days, the Moon will grow and move towards the Northeast among the stars, thereby approaching Jupiter and Saturn, but the encounter will not occur before the next edition of this newspaper. Jupiter dominates the evening sky, and is high above south already in the early evening, and Saturn is to the east of Jupiter, much fainter, but still quite conspicuous among the stars.
   Venus is now passing above the stars of Scorpius; on January 7, Venus will pass well above the brightest star of that constellation, Antares. Antares is a first-magnitude star, but is no competition for Venus, which gives us about 100 times more light than Antares. These two shine above the south-eastern horizon after about 5 a.m.
Speaking about the morning sky, let me mention that the latest sunrise will occur around January 9, and from then on, the Sun will start rising earlier, although for some time, you will hardly notice any striking difference.
   Orion and His Suite Above Santa Monica
This coming week, the Moon will not interfere seriously with your star watching, so this is a good time to get acquainted with the winter constellations. Our chart should help you to find the most prominent stars fast. Remember that all astronomical maps and charts are drawn in such a way that you are supposed to stand facing south and hold the map above your eyes, so that north on the map is behind your head, and west is to your right.
   Our starting direction would normally be the constellation Orion. It is so conspicuous that it is hardly necessary to show you the way to it. However, if you do star-watching in the early evening, say between 6 and 7 p.m., Orion may still be a bit too low for you, and perhaps obscured by the city lights in the east. Then it is best to start with the very bright Jupiter, high in the south. Jump from it eastward to Saturn, and continue in that direction until you see Aldebaran, a bright first-magnitude star of orange-red color. And you are already in our map, and finding Orion is then no problem; I am sure that from then on, you will be starting with Orion in order to find the prominent winter stars, including Aldebaran! 
   What makes Orion so conspicuous? No great imagination is needed to see a prominent figure in this constellation. Traditionally, people saw Orion as a fairy-tale giant. The bright reddish star Betelgeuse is in his right (eastern) shoulder, and the other first-magnitude star, Rigel, is in his left (western) knee. In this picture, the giant is facing you. Actually, according to the ancient Greeks, Orion was not interested in you, but in the dangerous bull attacking him from the northwest. The Bull (Taurus) shows you a prominent, fiery-red eye, and this is the star Aldebaran.
   I am not a warrior-like character, and to my eyes, Orion is a pretty girl, with a nice slim waist, formed by the three stars of the second magnitude, arranged in a nice short straight line (marked as "belt" in our chart). You may object that my pretty girl has no legs, if Rigel and another fairly bright star mark her knees. I will reply that the same is true about the giant, if he is what you want to see in the constellation. We ought not demand too much from stars!
   Orion is rich in bright stars. Only two other constellations contain two stars of the first magnitude: Centaurus and Southern Cross. These two constellations are unfortunately too far south for us to see them from California. Centaurus is a very large constellation, rich in bright stars, some of which we can see from here above the southern horizon in the spring. However, the entire constellation shows no definite pattern. And the two first-magnitude stars are too far south for us. In contrast to Centaurus or Orion, the Southern Cross is a very small constellation; the chart we are showing here is drawn on the same scale as the main chart - compare it with Orion and you will see how small the Southern Cross (in astronomical parlance, the name is simply Crux) actually is! It was actually carved out of Centaurus in the Middle Ages, when the cross was accepted as the symbol of Christianity. Both the Cross and the main stars of Centaurus become well visible when you travel south below the latitude + 20 degrees. You may still be on U.S. territory: for example, on Virgin Islands or on the largest island of Hawaii. For us on the northern hemisphere, both Centaurus and Crux are spring constellations, and we will say more about them in the spring. 
   In my opinion, Orion is the most impressive constellation, now that I have seen the Cross -- of course, for years my big desire was to see the Southern Cross! A few years ago, on the island of Moorea in Tahiti, I walked out of our motel room to admire the southern constellations. The motel guard was very suspicious, and it took me quite a time to convince him that I am really interested in stars, not in other people's property. To make amends, he told me: "Come with me to the north shore, and I will show you something very beautiful and yet so rare that only very few people will see it in their entire life." And he led me to the water's edge and pointed just above the ocean waters to the north -- and there was the Big Dipper!
   The lesson is, let us first enjoy what we can see from here! The three stars in Orion's belt, of equal brightness and equally spaced from each other, may well be the most conspicuous part of the constellation. And they can help you identify two other important stars. If you extend the belt in the northwestern direction, you will find Aldebaran, and higher beyond it, the star cluster of the Pleiades. You may be familiar with both, so it is more important to extend the direction of the belt to the southeast. There you will find the brightest star of our sky, Sirius, in the constellation of the Big Dog (Canis maior). I should qualify the term "the brightest star of our sky." Venus and Jupiter, and occasionally even Mars, are brighter than Sirius -- but they are not genuine stars, they are planets of our solar system. Sirius is a real star, but it appears as the brightest star only because it is relatively close to us -- "only" 9 light years distant. There are many stars that are actually much more luminous than Sirius, but they are much farther away. So Sirius is only the apparently brightest star -- but if you forget my astronomical arguments, you will agree that it is an impressive object and deserves its name, which means "sparkling". I will have more to tell you about Sirius and other winter stars. For the time being, enjoy them as they appear to you!