Thursday, October 23, 2008

The Ellensburg sky for the week of 10/25/08

Today: Been to the eye doctor lately? If not, an ancient vision test was the ability to see Mizar and Alcor as two stars. Mizar is the bright star at the bend of the Big Dipper handle. Alcor is the dimmer star less than a pinky width above it. Someone with superhero vision (or eyes that are eight inches in diameter) will also see Mizar as two stars. In 1650, Mizar became the first binary star discovered. Mizar and Alcor are three fists held upright and at arm’s length above the northwest horizon at 8 p.m.

Sunday: Mercury and the moon team up in the constellation Virgo this morning. Mercury is about a half a fist above the east horizon and a half a fist to the lower left of the moon at 6:30 a.m.

Monday: Antares may mean “rival of Mars”. But, this morning it is making an attempt to rival the brightest point of light in the sky – the planet Venus. Let’s look at the stats for each. Antares has a diameter more than 500 times greater than the Sun’s. If it were to replace the Sun in our Solar System, it would fill the entire inner Solar System all the way out to Jupiter. Antares is as bright as about 10,000 Suns. Venus, on the other hand, is a little bit smaller than Earth. It does not produce any of its own light. This looks like a one sided rivalry to me. Sort of like comparing Central Washington University’s football team to the other lousy “big time” football teams in the state. Antares is about a thumb thickness below Venus, less than one fist above the southwest horizon at 6:30 p.m.

Tuesday: 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.

Wednesday: Saturn is three fists above the east-southeast horizon at 6:30 a.m.

Thursday: Arcturus is one fist above the west-northwest horizon at 7 p.m.

Friday: Halloween. The pumpkins. The candy. The children going door-to-door dressed up has their favorite astronomers Harlow Shapley and Williamina Fleming. At least they should because Halloween is, in part, an astronomical holiday. Halloween is a “cross-quarter date”, a day approximately midway between an equinox and a solstice. Historically, the Celts of the British Isles used cross-quarter dates as the beginnings of seasons. For the Celts, winter began with Halloween. So when all those little Flemings and Shapleys come to your door, honor the Celts and give them a wintry treat.

The positional information in this column about stars and any planet except Mercury is accurate for the entire week.

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