Starry Skies Above Santa Monica

November 14-21, 2000

Mirek Plavec
Emeritus Professor of Astronomy,
UCLA

   Meteors are coming!
   I’ve published here three “advance warnings” concerning the expected meteor shower (or storm), and I am happy to announce that the meteors’ time has come, and there will be no more advance warnings! Let me repeat the essential facts from the previous week!
   It very rarely happens that we run into a dense swarm of meteors, ejected by their parental comet during one of its explosions. Such an exceptional event may occur in the pre-dawn hours of the night of Saturday/Sunday, November 17/18. We hope to encounter a fairly dense swarm of meteors ejected by the comet Tempel-Tuttle.
   The reader may lift his eyebrows here and say, “MAY occur? We HOPE? What kind of talk is it for a scientist?!” Well, realistically, we can’t see even a extremely dense cloud of meteors until we run into it We can only rely on a prediction based on a careful examination of past events.
   And detailed studies tell us that there is a good chance for us to see plenty of meteors! How many? Probably several hundreds per hour, perhaps a thousand per hour, perhaps even several thousand! Three factors play a role here. One is the altitude of the “radiant point” above the horizon. The meteors come to us from space in parallel orbits. In perspective, they appear to be “radiating” from a definite point among the stars. In this particular case, the radiant point lies in the constellation Leo, the Lion. (This is why this meteor stream is known as “the Leonids”). The closer the radiant point is to the zenith, the more meteors we can expect. This aspect we cannot change, and you will not consider it very favorable: the radiant will appear above our eastern horizon at midnight, and slowly rise higher. And it will be highest (almost in the south, but still a little to the east from the meridian) by 5 a.m., when the Sun will begin to illuminate our upper atmosphere and gradually extinguish stars as well as meteors…
   The second factor could be changed, at least by some of you: If you want to see the meteors, try going to some place where you can freely see at least the eastern and southern parts of the sky, and where the city lights do not blind your eyes. This fall, we have had almost endless morning fogs. It may change, miraculously, for that weekend. Yet it would be safer to escape from from the sea and the city, preferably somewhere in the desert. If you do that, please be prepared for the cold!
   And there is the third factor, which we also cannot change, and, moreover, we cannot evaluate it reliably! This is the density of meteors at that place in space through which we will be passing! Astronomers can make only predictions based on the previous history of the Leonids. It is probable that the number of meteors will be steadily increasing from midnight till dawn. Surprises are possible – there may be an unexpected high peak of activity! If so, it would probably not last too long – one hour, more likely even less than one hour If you do not want to sit outside for all those hours, it might be good to check the sky at intervals of, say, 20 minutes or so. There is something quite exciting in this, so please take it as an interesting game – and as an event that you might, just might, remember all your life… I am really curious what will happen! We are going to the Anza Borrego desert, which is lower and warmer than our northern desert. And we will see – unless it rains there on that night!
   Yet another factor is the Moon, but it will be extremely friendly – that is, it will not shine at all. It will be New – and therefore invisible – on Thursday, November 15. And by the weekend, it will only manage to be a thin crescent, setting rather early after sunset. On that Saturday/Sunday night, it will set at 7 p.m., while the Sun will set already by 4:48. The Moon will be projected into Sagittarius, and some distance from it to the east, you will see planet Mars, in the constellation of Capricorn. The Moon will pass below Mars during the day on Wednesday, November 21, and will reach its First Quarter one day later. Mars will be setting, this coming week, in the south-west after 10 p.m.

   The Two Bright Evening Planets
   The constellation of Taurus, the Bull, will appear above the north-eastern horizon at about 6 p.m. Normally, its first-magnitude reddish star, Aldebaran (considered to be the red eye of the bull) is fairly impressive, but this time, it is easily beaten by Saturn, which follows it, as Saturn is positioned a bit to the north-east of Aldebaran.
   However, Saturn’s domination will not last long, since at 8 p.m., the much brighter Jupiter emerges to the northeast of Saturn. Jupiter is projected into the middle of the constellation Gemini (the Celestial Twins – its two leading stars, Castor and Pollux, come up about half-an-hour later.) By that time, the magnificent Orion is already rising above the east, and before 10 p.m., the brightest real star, Sirius, appears in the south-east. By its brightness, it is second only to Jupiter.

   The Sky at the Leonid Hour
   At the time when we expect and hope to see the meteors, in the pre-morning hours of Sunday, November 18, all the prominent winter constellations will already be fairly high up in the east. Venus, brighter even than Jupiter, will emerge in the south-east quite late, at 5:30 a.m. By that time, the sky background will already be getting fairly bright.