Tuesday, November 30, 2010

The Ellensburg sky for the week of 12/4/10

Saturday: The earliest sunset of the year occurs this week, about 4:17 p.m. This seems odd because the shortest day of the year, the winter solstice, isn’t for about two more weeks. The Sun is at its southernmost point with respect to the background stars on the day of the winter solstice. This means the Sun spends the least amount of time above the horizon on that day. But, the Sun rise and set time depends on more than its apparent vertical motion. It also depends on where the Sun is on the analemma, that skinny figure-8 you see on globes and world maps. During the second week in December, the Sun is not quite to the bottom of the analemma. But, it is on the leading edge of the analemma, the first section to go below the horizon.

Sunday: Tonight’s Moon is new. Don’t bother looking for it. The new moon is the phase where the Moon is directly between the Earth and the Sun. Hence the side of the Moon facing Earth is not receiving any sunlight and cannot be seen.

Monday: The young crescent Moon helps mark the location of two planets very low in the southwest sky right after sunset. The Moon is just above the southwest horizon at 4:45 p.m. Mars is about a pinky width to the lower right of the Moon and Mercury is about a half a fist to the upper left of the Moon.

Tuesday: “Hey baby! What’s your sign?”
“Ophiuchus, of course”
The Sun is in the same part of the sky as the stars of Ophiuchus from about November 29 to December 17. This is what astrologers mean when they say the Sun is “in” a constellation. Thus, if you were born between these dates, you should be an Ophiuchus. The fact that the horoscopes never list Ophiuchus is a major flaw of astrology. Astrology says that some of our characteristics are based on the location of the Sun at our birth. How can astrologers leave out three weeks from their system? That is like a scientist saying she can explain the results of her experiment every month of the year except early December. Ophiuchus was a mythical healer who was a forerunner to Hippocrates. According to myth, he could raise people from the dead. Maybe that is why he is ignored by astrology. Raising people from the dead is much less impressive than giving spot-on advice such as “Today is a good day to watch your finances.”
The bright stars of Ophiuchus rise just before the Sun. Rasalhague (pronounced Ras’-al-hay’-gwee), the brightest star, is about one fist held upright and at arm’s length above the east horizon at 6:30 a.m.

Wednesday: Venus is about two fists and Saturn is about three and a half fists above the south-southeast horizon at 6:30 a.m.

Thursday: When Galileo aimed his telescope towards the sky, he knew of only one Sun-like star: the Sun. By the early twentieth century, Annie Jump Cannon, Williamina Fleming and others had developed a scheme for classifying stars so astronomers could identify other Sun-like stars. But it wasn’t until the last few years that astronomers have discovered planets around some of those Sun -like stars. Some astronomers estimate that one out of every four stars like our Sun may be orbited by Earth-like planets. Of course, the definition of Earth-like typically means a rocky planet about the mass and radius of the Earth. So don’t start saving up for that interstellar vacation yet. But in the next few years, satellites such as Kepler will start imaging Earth-like planets. Not long after that, astronomers will be able to study the atmospheres of those planets and look for clues that the planet might have life. For more information about discovering new worlds, go to http://astronomy2009.nasa.gov/topics_dec.htm.

Friday: Jupiter is four fists above the south horizon at 6 p.m.

The positional information in this column about stars and planets is typically accurate for the entire week.

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