Starry Skies Above Santa Monica
April 18-25, 2000

Mirek Plavec 
Emeritus Professor of Astronomy, 
UCLA

   Sun, Moon, Planets, and A Bit of Astrology
   Since last Sunday, the Sun progressed even higher above the celestial equator, and on Sunday, April 22, it will be more than 12 degrees above the equator. Thus, at the local noon, the Sun will pass overhead over places like San Salvador, the islands Grenada and Aruba in the Caribbean, Guam in the Pacific, over the cities Bangalore and Madras in India, and also over Krung Thep in Thailand, better known by the older name of Bangkok. 
   For us, the Sun will pass 22 degrees south of the zenith, but you may very well feel that the Sun is virtually overhead. On Sunday, April 22, the Sun will rise at 6:13 (a gain of 9 minutes), and set at 7:30 p.m. (a gain of 5 minutes). On that day, the Sun will cross from the constellation of Pisces into Aries. 
   People born between March 21 and April 21 think that their “sun sign” is Aries, but during that time, the Sun is in Pisces, not in Aries. When Claudius Ptolemy codified astrology in 150 AD, the Sun was really in Aries between March 21 and April 21. Since that time, a process called “precession” shifted the signs of the zodiac just about by one constellation – so now the Sun is, at this time of year, in Pisces (the Fishes). Don’t worry, it is quite irrelevant whether you were born under Aries or Pisces. Remember that one of the worst beasts in human history, Adolf Hitler, was born on April 20 –- and you certainly don’t want to share anything in your character with him! 
   Or, if you do believe in astrology, you should realize that the grandfather of astrology, Ptolemy, did also associate each “sign” (that is, constellation) of the zodiac with a part of human body: thus Aries rules over your ears, lung diseases are the responsibility of Gemini, and your feet are influenced by the planet that happens to be in Pisces.
   Ptolemy also decided that Venus and Jupiter are friendly planets, while Mars and Saturn are always bad guys. Thus, when Mars is in Pisces, then according to Ptolemy, you will suffer from excessive perspiration of your feet. Mars is currently pretty far from Pisces, so your feet should be OK, but Mars is very close to Scorpius, and Scorpius allegedly rules over our sexual organs. If you believe in astrology, please be extra cautious during the next few months! 
   OK, back to reality! The Moon was in its Last Quarter phase on April 15, rising around 1 a.m. (which is actually midnight, remember!). On the following mornings, the Moon will appear thinner and thinner. The Moon will be New (and therefore invisible) on April 23. Before that, a very thin crescent will pass below Venus on the mornings of April 20 and 21. These encounters, more scientifically called “conjunctions”, often create a beautiful pair of objects close together: the crescent Moon and the brilliant Venus. This time, the Moon will be passing rather far to the south of Venus, and the show will be short, since Venus rises by 4:38 a.m., and shortly afterwards, the eastern sky will begin to brighten, announcing the arrival of the Sun.
   If you get up sufficiently early to see Venus above the eastern horizon, then you should also look for Mars. Mars is less bright than Venus, but it is approaching its maximum brightness, which makes this planet already quite conspicuous – as bright as the brightest stars, and rather conspicuously reddish in color. You can search for Mars any time after midnight, but you must have a good view of the south-eastern horizon. 
   The two evening planets, Jupiter and Saturn, are still visible, but their show is rapidly coming to an end. You must search for them above the western horizon fairly soon after sunset. You can spot Jupiter already shortly after 8 p.m.; it is quite bright, but it will set at about 10:30 p.m. Saturn, significantly fainter than Jupiter but still a first magnitude “star” lies to the west of Jupiter and will therefore disappear earlier, by 9:30 p.m. Disappearing with them from our starry sky is the prominent star cluster of the Pleiades, located to the north of Saturn, and the reddish star Aldebaran (“the Bull’s Eye”) below Jupiter.

   Meteors Are Coming!
   I was rather surprised to hear from several of my UCLA students that they have never seen “a shooting star,” as they say. Obviously, this is what life in big cities does to us: all the beauty and excitement of the starry sky are gone -– although I think that they do spend at least a few weeks in the summer far out from city lights, so they do get the opportunity to see at least a few “shooting stars” if they are patient enough to watch the sky for an hour or so. 
   If you lie down comfortably in a deck-chair and watch the starry sky, you should be able to see a few of those meteors on any moonless night. Yes, the “shooting stars” or “falling stars” are neither stars nor shooting: they are small pebbles or more likely “dirty snowballs” that enter our atmosphere at high speed -– and I really mean high speed, since they come at speeds between 20 and 70 kilometers per second! As they collide with the air molecules, they excite electrons in the individual atoms, and as the electrons fall back closer to the atomic nucleus, they emit radiation. The show, however, is very soon over, since the resistance of the air quickly breaks up the meteor, which ceases to shine some 70 - 100 kilometers above our heads. 
   The number of meteors you can see between January and early April is rather low. If they appear, they move across the sky at random. April is the first month when you stand a good chance to see more meteors. The regular “meteor stream” of the Lyrids crosses the orbit of the Earth on the night of April 21/22. This is Saturday night, and this year, the Moon does not interfere. The only disadvantage of the Lyrids is that their activity is higher in the morning hours. As the meteors move in parallel orbits, they appear to us “radiate” from a point in the sky (the “radiant”) which, in this case, happens to lie close to the bright star Vega in the constellation of Lyra. Vega rises in the north-east at about 10 p.m. The higher the radiant gets in the sky, the greater is the chance to see more meteors.
   Thus, the hours after midnight (early Sunday) are most promising, and you may see some 20 meteors per hour. Your best chance is to watch the sky above your head – the meteors will be coming from the north-east. If you miss this opportunity, don’t worry, you will get a better chance, especially in August, when the nights are warmer.