Starry Skies Above Santa Monica

January 30 - February 6, 2002

Mirek Plavec
Emeritus Professor of Astronomy,
UCLA

   The Sun, High Over Down There
   The Sun is now passing directly overhead, at noon local time. over Arequipa (Peru), Cochabamba (Bolivia), and Goiania (Brazil) – as you can see, I had to study the World Atlas in great detail! For us, the Sun passes more than 50 degrees south of the zenith – that is, even at noon, it is still 5 degrees closer to the southern horizon than to our zenith.
   On Sunday, February 3, the Sun will rise at 6:48 – 6 minutes earlier than a week ago, and will set by 5:25 p.m., 7 minutes later than on the previous Sunday. As you can see, the Sun has improved its score, and adds just about one minute to our daylight on both sides, morning and evening.
Astronomically speaking, the Sun is now traveling in front of the stars of Capricorn. As its name suggests, this constellation represents the “sea goat” – whatever that is, but is more often seen, especially by the northern nations, as a “mountain goat,” climbing up the steep rocks just like the Sun is moving northward in the sky, one step higher every day.

   The Moon
   – Receding into the Night
   The Moon was exactly Full in the afternoon of Monday, January 28, and was projected into Cancer. Since then, it has risen later and later on every successive night, showing less and less of its illuminated face. At the same time, the Moon has not only been steadily moving eastward, but also descending along the ecliptic southward. The Last Quarter phase will come in the morning of February 4 The Moon will then be projected into Libra (the Scales). There are no bright stars in that constellation, but not far to the west is Spica in Virgo, and to the east is Antares, in Scorpius. The Moon will be close, and above, Spica on the two preceding mornings, and will then pass above Antares in the morning of February 6 (Wednesday). By that time, the Moon will be a crescent, 30% of its disk illuminated.

   Two Planets Too Close to the Sun: Mercury and Venus
   Mercury will be a bit farther from the Sun, preceding it in rising, but too far from us and too faint to be seen. Venus is very bright, setting after the Sun in the early evening, but is still projected so close to the Sun that it probably also remains invisible. It will set 21 minutes after the sunset, and at that time, the western sky will still be too bright and will obliterate Venus. Nevertheless, should you have the opportunity to watch the sunset above the ocean, try to look for Venus (with your eyes or with binoculars) just above the place where the Sun has set.

   Still Three Bright Evening Planets
   Mars crossed the celestial equator and moves through the constellation of Pisces (the Fishes).    Mars shines now only as a star of magnitude 1.1. However, it travels through a region of the sky where there is no competing bright star, and therefore Mars remains fairly prominent, but it sets fairly early, before 10 p.m.
   The two big and bright planets, Saturn and Jupiter, shine now high above the eastern horizon in the early hours of the evening. The starry sky we see in the evening is fairly rich in bright stars and planets. If you look around 7: 30 p.m. (actually at any time during the long evening), you will be able to identify Jupiter without difficulty: it is by far the brightest “star” high above the east or south-east (actually fairly close to the zenith, since it culminates at about 9:30 p.m.). Jupiter’s only competition is a real star, namely Sirius in the Big Dog. Sirius lies well below the celestial equator, so you will see it in the south-east; it culminates above the south by about 9:30.
   Saturn shines as a star of the first magnitude (more accurately, 0.8), significantly fainter than Jupiter (which, on our astronomical scale, is of magnitude -2.6 – these numbers tell us that we get 23 times more light from Jupiter than from Saturn). Nevertheless, even Saturn is easy to find if the evening is clear: it forms a fairly close pair of bright “stars” with the reddish Aldebaran in Taurus (the Bull). This fairly prominent pair precedes Jupiter, that is, it is higher above the southeast when stars begin to be visible (this is about 6:30 p.m.). Saturn with Aldebaran culminate above the south already by 7:30 p.m., and after that, you must look for them in the south-western sky, although they are still “almost overhead” before midnight.

   Meet the Mighty Orion
   The four bright objects, Jupiter, Sirius, and Saturn with Aldebaran, form a big celestial triangle, and inside this triangle – or, perhaps better, about halfway on that side of the triangle that connects Saturn and Sirius – is the magnificent constellation of Orion. Orion has two first magnitude stars that beat both Saturn and Aldebaran in brightness, although not strikingly so: Beteigeuze and Rigel. It seems to me, however, that Orion is best recognized by the traditionally famous “three in a row” – three stars of the second magnitude arranged along a short straight line. They lie practically on the celestial equator, which also means that they pass overhead for people living at the terrestrial equator.
   All these three stars are actually fairly big – giants or rather supergiants – and very hot on top of that, and therefore actually very luminous, producing much more radiation than our Sun. However, they are rather distant stars. We are still not sure how far they are, but 1,500 light years seems to be a good guess. Remember that Sirius is only 9 light years away.