October 23, 2000
|
Subscribe now to receive |
1. Astronomers like to think that things are looking up; we certainly are. After a long summer without bright planets, our situation is improving as the long nights of winter arrive. Venus is fabulous in the southwest at twilight, while Jupiter and Saturn dominate the rest of the November night. Even Mars is returning for morning appearances. If you look in the mid-to-late evening, the great square of Pegasus will be the dominant constellation overhead. As you face south, the upper-left corner star is Alpheratz, the brightest star of the neighboring constellation, Andromeda.
2. We celebrate the 115th birthday of Harlow Shapley today. Kansans may like to remember that Shapley was a crime reporter in Chanute; Missourians will point out that Shapley graduated from the University of Missouri at Columbia. Shapley's plans to study journalism went by the wayside when he studied astronomy there. Shapley remained one of the greatest students of the Milky Way galaxy, the first to devise a means to study its true extent.
3. The first-quarter moon is at the distant rim of its Earth-centered orbit, 90 degrees behind the sun at 1:27 a.m. tomorrow. The moon will set with Capricornus before 11 p.m. Although they can't be seen without a telescope, Uranus and Neptune are near the moon this evening, Uranus to its upper left, and even dimmer Neptune to the moon's upper right.
6. One of the easier constellations to learn is Cassiopeia, recognizable for its W shape. Cassiopeia is nearly overhead these November evenings, typically high when the Big Dipper (Ursa Major) is low in the north. On this date in 1572, something sort of odd happened--a new star appeared in Cassiopeia. This was one of only two supernovas witnessed in our own galaxy over the past four centuries. After a week or so of skeptical denial, the great Danish astronomer, Tycho Brahe, made extremely valuable observations that make it possible for us to study the remnant of this event 428 years later.
8. We think we live in exciting times? Edmond Halley was born on this date in 1656. He was witness and participant in some of the most exciting scientific adventures of the age of discovery. Halley made the first charts of the oceans' magnetic fields and planned calculations and expeditions to study the rare and important transits of Venus across the face of the sun in 1761. He was the second astronomer royal of England. And yes, he did discover a comet. He never saw the comet that bears his name; his achievement was to recognize from its orbit that past historical appearances were of a predictable object orbiting the sun once every 76 years.
11. The moon has a very full agenda over the next two days. First, it must tick off full phase at 3:15 p.m. today. We won't be able to see that when it occurs. No matter, the moon in opposition will be up all night. The moon is also hosting a conjunction with Saturn. By morning, the moon will pull within 1.5 degrees of our beautifully ringed neighbor.
12. This is the 20th anniversary of Voyager 1's closest approach to the planet Saturn. We remember Saturn as the moon's near neighbor last night. It will be left behind as the moon marches eastward for an encounter this evening with Jupiter.
15. Another exciting life began on this date in 1738, the birth date of William Herschel. Herschel is mostly widely known as the first telescopic discoverer of a planet in 1781, but astronomers revere Herschel's memory for much more. He practically invented the systematic study of stars and developed one of the first crude pictures of the Milky Way as a huge stellar system. Herschel recorded the first observation of a planetary nebula, a diaphanous bubble of gas surrounding a dying star and was the first to recognize that stars prefer to live in pairs and larger systems.
18. Leo actually looks like a mighty constellation, with its brilliant star, Regulus, and its lion-like form. What a fine constellation for the moon to pass through for its last phase of the month. The moon rounds out its last phase for this lunation at 9:24 a.m.
19. One of Saturn's big moments this year will arrive a little past sunrise for Kansans but you won't miss much if you look for Saturn a few hours earlier. Saturn is at opposition today, with Earth squarely between the sun and this giant planet. Saturn's average distance from the sun is about 10 times greater than Earth's. Can you imagine a sun 10 times smaller in the sky and 100 times fainter? That's how it would appear from a world in Saturn's sphere of influence.
21. You might be able to enjoy some of the nicer morning sky features from a warm, dark room if it has a clear view of the eastern horizon at 6 a.m. The moon is a few days shy of its new phase, and Mars is just a few degrees to the south. The bright star below this pair is Spica, the brightest of the constellation Virgo. If your view of the horizon is really clear, you may spot Mercury ahead of the sun in the hour before 7 a.m.
25. The moon is just a little north of the sun as it passes new phase at 5:11 p.m. If we could see behind the sun's glare we would see the stars of the constellation Scorpius and the bright star Antares a little south of the sun.
27. Centuries ago, certain configurations of the major planets carried great significance to astronomer-priests who studied the skies to predict the will of the gods. We no longer attach the same concern to these celestial milestones but the opposition of a bright planet is still a happy event. Jupiter is at opposition this evening, placing it above the horizon for the entire night. Our giant neighbor is also at its closest to Earth, making it brighter and a bit larger in a telescope. Jupiter's closest competition, nearby Saturn, is 75 times fainter.
29. Some natural wonders retain their beauty no matter how many times you are privileged to see them. One of the real advantages of approaching winter is the earlier hour of sunset. By 6 p.m., the sun is far enough below the horizon that the western sky is fairly dark. You'll have no trouble finding Venus and its near neighbor, the waxing crescent moon.
-30-