Thursday, January 7, 2010

The Ellensburg sky for the week of 1/9/10

Saturday: The ringed planet, Saturn, is making its way into the evening sky. It is about a fist held upright and at arm’s length above the east horizon at midnight. Its famous rings don’t look as spectacular because we are looking at them nearly edge on.

Sunday: Jupiter is one and a half fists above the southwest horizon at 6 p.m.

Monday: Antares is about a pinky’s width to the upper right of the Moon at 7 a.m. They are in the southeast sky. If you think a pinky’s width is close, talk to someone in Boston at this time. In the far northeastern corner of the United States, northeast of a line from Boston, through Vermont, and into New York, the Moon will pass between the Earth and Antares leading to an occultation of Antares. You can follow the Moon-star pair in Ellensburg even after sunrise as Antares will stay in the same relative position for the next few hours. By then you’ll need binoculars.

Tuesday: This morning take the M-M challenge. No, not the M&M challenge. Nothing will melt in your mouth. And not the Eminem challenge either. You’re not Slim Shady, no, you’re not the real Slim Shady. I mean the Mercury-Moon challenge. Mercury is one fist to the left of the Moon at 7 a.m. They are less than a half a fist above the southeast horizon. Because of the rising Sun, it will be a challenge to see both M objects.

Wednesday: January is the coldest month of the year so it is time to turn up the furnace. Fornax the furnace one fist above due south at 7 p.m.

Thursday: 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. But if you live anywhere from central Africa to east Asia, you will see the effects of the new Moon: it will block part of the Sun. Most of the people in that region will see a partial eclipse. Depending exactly where you live, the Moon will take a “bite” out of the Sun varying from a tiny nibble to a “you almost took my fingers off” giant bite. The lucky few who live along a 200 mile wide path from central Africa to east Asia will see an annular eclipse.
Despite the word similarity, annular does not mean once a year. Annular means “ring-shaped”. An annular solar eclipse occurs when the Moon, as seen from Earth, is not large enough to cover the Sun even then they are perfectly lined up. We sometimes have total solar eclipses and sometimes have annular solar eclipses because the Moon is not always the same distance from the Earth and the Earth is not always the same distance from the Sun.
Here is the difference between a total solar eclipse and an annular solar eclipse. Take a coin out of your pocket. Close one eye. Hold the coin close to your open eye such that you completely cover a round object across the room. This represents a total eclipse of that object. Now, slowly move the coin away from your eye until you can see an outline of the round object. This is an annular eclipse of that object. Your coin, representing the Moon, has too small of an angular size to completely cover the round object across the room, representing the Sun.

Friday: Mars is three fists above due east at 9 p.m.

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

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