Starry Skies Above Santa Monica

August 8-15, 2002

Mirek Plavec
Emeritus Professor of Astronomy,
UCLA

   The Perseid Meteors Are Here!
   The meteor stream of the Perseids will reach its peak activity in the late hours of the night of August 12/13, that is, in the pre-dawn hours of next Tuesday. Actually, quite a few meteors can be seen on Saturday and Sunday nights now, but, unfortunately, always rather late, after midnight. Why are they so unfriendly?
   Actually, the meteors form a fairly broad stream through which the Earth is passing for a number of days. The problem with late-night visibility comes from the fact that it is at those late hours that the rotating Earth brings us to face the direction from which the meteors are coming. They appear to “radiate” from a point in the constellation of Perseus, which emerges above the north-eastern horizon after 10 p.m. The higher the “radiant point” is above the horizon, the greater is the number of meteors you can see. And the radiant rises rather slowly, so the best time for seeing the meteors comes later after midnight.
   If you decide to watch the meteors, find a place far from the city lights, lie comfortably in a reclining chair, and dress up as if you were preparing to encounter a snow storm – even the August nights can become rather chilly, especially in the desert, and when you move very little.
   You do not have to look to the northeast, where the constellation of Perseus, with the radiant point, gradually rises. The meteors will flash all over the sky, with an interesting difference. If you face the radiant, you will mostly see very short flashes. It may happen that you will see a “stationary meteor,” namely the one that is aiming directly at you. Don’t panic and don’t run away, that tiny piece of rock will disintegrate at least 60 kilometers above your head, probably even higher!
   If you face the zenith, or even the southwestern part of the sky, you will still see many meteors, and they will be more conspicuous, since they will travel in apparently longer luminous paths, and they will appear to be quite swift. You can expect to see some 60 to 100 meteors per hour during the nights around the maximum activity, if the sky is clear, transparent, and city lights do not blind your eyes.
   The celestial enemy of meteor watchers, the Moon, is very kind to us this year. It will be New Thursday, August 8, and on the following nights, it will gradually appear as a slowly growing crescent above the western horizon after sunset. On the night of the maximum Perseid activity (August 12/13), it will still be a fairly thin crescent, and will set before 10 p.m.
   Before that, on August 11, the Moon will pass above the brilliant Venus, which sets in the west after 9:30 p.m.

   Discovery of a Cosmic Hamburger
   Dr. Arturo Gomez, an astronomer at the Cerro Tololo Inter-American Observatory in Chile, found, in one of his photographs, a strange oblong object with a dark band cutting it in two parallel halves. Not much more could be found about it from terrestrial photographs, since the ever-present atmospheric turbulence does not permit a precise study of the details.
   Therefore, the Hubble Space Telescope used its excellent “wide-field planetary camera” to take a picture of the object on February 22, 2002. A detailed study established that it is actually a star like our Sun, but so advanced in life that it is near the end of its truly stellar life, and is on its way to become a glowing nebula -– of a type that is called a “planetary nebula,” merely because some of these objects resemble something like the planets Jupiter or Saturn when observed in a moderate-size amateur telescope.
  When forming such a planetary nebula, the star expels large amounts of gas and dust, often along its equatorial plane, so the object is considerably flattened -– far from the spherical shape of a star. Rapid rotation of such a star is initially responsible for the final shape of the object.
   Have you ever wondered what the ingredients in the hamburger you are eating might be? Well, the composition of the celestial hamburger is definitely different! Its ingredients are dust and – light! The two buns consist of dust that scatters and reflects the light of the decaying star, and the patty is formed by a dark band of dense dust in the middle!
   I think that, considering such a composition, not even the most ardent lover of hamburgers would like to eat this one – which is just as well, since the Gomez Hamburger is a bit out of your reach. It is located some 6,500 light years away from us, in the constellation of Sagittarius.

   A Record-Breaking Thunderstorm
   I know, it’s actually not my business to talk about our terrestrial weather. I might use a weak excuse claiming that “meteors” and “meteorology” are closely connected words, since both referred, for the ancient Greeks, to the phenomena in our atmosphere. Moreover, you may have read the story about a New York thunderstorm, published in L.A. Times on Sunday, August 4. Or again, you may have missed it, and I think it is worth noticing.
   Lightning hit the ground an estimated 5,000 to 7,000 times across the New York metropolitan area in a three-hour span during a storm that deposited more than an inch of rain. That’s really something – can you imagine so many lightning flashes?