Tuesday, March 8, 2011

The Ellensburg sky for the week of 3/12/11

Saturday: Don't forget to set you clocks ahead one hour tonight for the annual ritual called daylight savings. Daylight savings originated in the United States during World War I to save energy for the war effort. But a recent study by two economists shows that switching to daylight savings time may actually lead to higher utility bills. When the economists compared the last three years of energy bills in the section of Indiana that just started observing daylight savings, they discovered that switching to daylight savings cost Indiana utility customers $8.6 million in electricity. In an even more important consequence of daylight savings, Stanley Coren of the University of British Columbia discovered a 7% jump in traffic accidents on the Monday after we "spring ahead". Blame it on the lost hour of sleep. And, sky watchers will lose even more sleep because the sky does not get dark for an additional hour.

Sunday: Jupiter, the largest planet in the Solar System, is a half a fist above the west horizon at 8 p.m. Mercury, the smallest planet in the Solar System, is a couple finger widths to the lower right of Jupiter.

Monday: The Moon is midway between the twin stars in Gemini and the little Dog Star. Procyon, the brightest star in the constellation Canis Minor, or the lesser dog, is one and a half fists below the Moon. Pollux and Castor are about a fist above the Moon. All of these objects are in the southern sky at 9 p.m.

Tuesday: Vega is a little more than a half a fist above the northeast horizon at 11:30 p.m.

Wednesday: This Saturday is Earth Sun day. For more information, go to http://sunearthday.nasa.gov/2011/index.php.

Thursday: Mercury is the naked eye planet we know the least about. That may soon change because NASA’s Messenger probe is scheduled to start orbiting Mercury today. It will be the first visitor to the planet one Messenger scientist called the most under-appreciated planet since 1974. The number one question scientists hope to answer is why Mercury has such a large iron core compared to its size. The number one question you may be asking is “Why is Mercury in a different location with respect to Jupiter since Sunday?”. It is now about a finger width to the upper right of Jupiter. Since mercury is so close to the Sun, it moves very fast in its orbit so it changes positions in the sky much faster than an outer planet such as Jupiter.

Friday: Ask someone on which day in March the day becomes longer than the night. Go ahead, ask someone. Why are you still reading this? I can wait. If they said the first or second day of spring, they are wrong. Today, two days before the first day of spring, is the day in which there are more minutes of daylight than night. There are two main reasons for this. First, the atmosphere acts like a lens, bending light from the Sun above the horizon when the Sun is actually below the horizon. This makes the Sun appear to rise before it actually rises and appear to set after is actually sets. Second, spring starts when the center of the Sun passes through the point called the vernal equinox. But, the Sun is not a point. The upper edge of the Sun rises about a minute before the center of the Sun and the lower edge sets a minute after the center of the Sun. Thus, even if we didn’t have an atmosphere that bends the sunlight, daytime on the first day of spring would still be longer than 12 hours.

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

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