Saturday: “You know Aries and Cancer and Draco and Libra. Leo and Pisces and Virgo and Hydra. But, do you recall, the pointiest asterism of all? Triangulum, the three sided asterism, had a very pointy edge….” Sorry. Some stores have started putting up their Christmas decorations and that put me in the mood. Anyway, Triangulum is a small constellation between the more prominent Andromeda and Aries. Its main feature is a skinny triangle oriented parallel to and nearly four fists held upright and at arm’s length above the east horizon at 10 p.m.
Sunday: Did you time the exact length of the day and night last Tuesday on the first day of autumn? They were not equal in duration. Many people think that the day and night are the same duration on the autumnal equinox. The day is a little longer than the night for two reasons. First, the Sun is an extended object so even when the middle part has set, the upper half is still above the horizon lighting the sky. The second, and more influential reason, is that the atmosphere acts like a lens, bending light from the Sun above the horizon when the Sun is really still below the horizon. Day and night are closest in duration today.
Monday: The International Year of Astronomy (IYA) is winding down. But the size of the objects being featured is not getting any smaller. This month’s Go Observe is the Andromeda Galaxy. On Saturday, I had you look for Triangulum. About one fist above Triangulum is a star twice as bright as the brightest star in Triangulum. From that star, hop about a half a fist up to a star that is about one fourth as bright as the bright star you just found. Less than another half fist in the same direction is a fuzzy oval patch of light called the Andromeda Galaxy. The galaxy is impressive to see in binoculars. It consists of about 400 billion stars and is 2.2 million light years away. For more information about the Andromeda Galaxy, go to http://astronomy2009.nasa.gov/observe.htm and click on October.
Tuesday: Jupiter is less than a half a fist to the lower right of the Moon at 9 p.m. Just to the lower left of Jupiter is the star iota Capricorni, a star a little bit larger than our Sun.
Wednesday: Astronomers, philosophers, and smart children have been contemplating the fate of the universe for centuries. Galileo did not start that trend. But by turning his telescope toward the night sky, he opened a new source of evidence for determining that fate. To honor Galileo’s contribution to this question, the IYA Hot Topic for October is “What is the fate of the universe?”. For more information, go to http://astronomy2009.nasa.gov/topics.htm and click on October.
Thursday: Mars is five and a half fists above the southeast horizon and Venus is one fist above the east horizon at 6 a.m.
Friday: Since Halloween is coming up, the stores are filled with bags of candy clusters. Instead, take time to look at a star cluster. The Hyades cluster is an open star cluster that represents the V-shaped face of Taurus the bull. It is one of the biggest and nearest star clusters with about 200 stars 150 light years away. The Hyades cluster was the first cluster to be the subject of detailed motion studies. These studies allowed astronomers to pinpoint the distance to the Hyades and provide important information about the scale of the universe. Aldebaran, one fist above the east horizon at 11 p.m., is a foreground star and not a part of the Hyades cluster.
The positional information in this column about stars and planets is typically accurate for the entire week.
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