Starry Skies Above Santa Monica

March 13-20, 2002

Mirek Plavec
Emeritus Professor of Astronomy,
UCLA

   Last Week of Winter
   On Wednesday. March 20, we will have the Spring Equinox! Most people believe that March 21 is the proper day for the equinox, but actually its date varies between March 20 and 22. For us, the lucky people living in Southern California, spring has been here for quite some time – look at the trees, roses, and many other garden flowers!
   A special day for timing the Sun is Saturday, March 16: The Sun will rise at 6:02 a.m., culminate at 12:02, and set at 6:02 p.m.!
   The Sun is completing its visit with Aquarius (the Water Bearer), and on March 20, it will cross the celestial equator and enter into Pisces (the Fishes).

   Five Planets in a Row!
   A rather unusual configuration of the five bright planets, which I mentioned last week, essentially continues this coming week: They are stretched along the ecliptic at nearly equal intervals. Lowest among them is Mercury, in Aquarius, almost 7 degrees below the celestial equator. This position makes it almost impossible for us to spot Mercury: it rises only half-an-hour before the Sun, and lies south of the point where the Sun will rise. In principle, Mercury is a morning star, preceding the Sun in rising. The rest of the planets are evening objects, much easier to see.
   About 30 minutes after sunset, you may try to spot Venus, above the place where the Sun has set. Venus will set by 7:10 p.m., so that it currently follows the Sun by 68 minutes. This is still not enough for an easy sighting of this bright planet: it is necessary to search for Venus above the ocean, not above the mountains, and then even the gentle cirrus clouds above the western horizon can easily obscure Venus.
   Higher up along the ecliptic is Mars, in Aries (the Ram), climbing higher along the ecliptic fairly fast, as if trying to remain visible for us! Mars is now barely as bright as a star of the first magnitude, and is still fairly conspicuous in the evening western sky just because there is no bright star in that region of the sky. The Earth has run so far away from Mars that its distance is currently 307 million km. Mars sets at about 9:30 p.m.
   You may object that both Saturn and especially Jupiter are much farther from us than Mars is, and yet they are quite prominent in the night sky – they are simply much bigger planets!
   Saturn is already to the west of the meridian when the sky becomes sufficiently dark, and then sets in the northwest before midnight. Saturn still forms a fairly close and fairly conspicuous pair with Aldebaran, the brightest star in Taurus (the Bull). Saturn lies a bit to the north of Aldebaran, and the loose star cluster of the Hyades is located between them.
   The evening sky is still dominated by Jupiter, which shines at the western edge of Gemini, close to the boundary with Taurus. Jupiter culminates above the south shortly after sunset, then moves to the western sky and sets shortly before 2 a.m.
   Only Sirius, lower in the sky and to the south, can compete with Jupiter in brightness (and loses, but not by that much). Sirius culminates shortly before 7 p.m., and if you watch the starry sky from a view point above the ocean, you may spot Canopus deep down in the south, just above the ocean.

   No, I did not forget the Moon!
   The Moon is not visible at the beginning of this week, since it is New tonight, March 13, Wednesday, it passes below the Sun, so no eclipse again! Some two or three evenings later, the Moon will become the beautiful Spring Moon, shining high above the western horizon as a silvery crescent.
   On the evening of March 17, the crescent Moon will pass 4 degrees below Mars. Then, on Tuesday evening, March 19, the (still crescent) Moon will contribute to a nice grouping in Taurus: to the east of the Moon, you will see Aldebaran and Saturn, and to the northwest of it will be the star cluster of the Pleiades. On March 20, the Moon will still be close to Saturn, while on the following two nights, you will be able to see it near Jupiter. The Moon then reaches its First Quarter on March 21.
   Even if no planetary encounter is scheduled for the Moon on the other nights, please go out in the evenings and look at the Moon! It is worth seeing how the silvery crescent rises higher and higher every successive evening.