MARCH  2005

MARCH STAR MAP | STARWATCH INDEX | MOON PHASE CALENDAR

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446    MARCH 6, 2005:   High on Mercury

I have always been intrigued by the planet Mercury. It is not my favorite sky target, but of the five classical planets, Mercury is by far the most challenging. Its closeness to the sun creates the difficulties that make viewing it, even through binoculars, a victory. For the next two weeks, if the weather cooperates, I hope to be able to observe Mercury as a star like object with just my eyes. Here is what is happening. As the Earth and Mercury revolve around the sun, we get to see Mercury’s motions play out right before sunrise or right after sunset, depending upon whether Mercury is west or east of the sun. There is an angle of greatest elongation when Mercury appears at its greatest separation from the sun. That occurs on March 12. The angle is to the east of the sun which means that Mercury will be visible after sunset in the west. Unfortunately, this event occurs only four days after Mercury has reached its closest distance to the sun. This means that as greatest elongations go, this one should be pretty lame. Enter the time of the year which means everything to how elongations are perceived. The planets orbit in nearly the same plane as the Earth. This plane is called the ecliptic. In the spring from mid-latitude locations in the Northern Hemisphere, the ecliptic intersects the horizon at its steepest angle. This allows planets like Mercury and Venus to remain above the horizon for their longest possible durations after sundown. From March 6-18, Mercury will be visible after sunset for about 1-1/2 hours. You will still need a flawless western horizon and a very clear evening. View with binoculars about 30 minutes after sundown about one full field of view above the horizon. Star like Mercury should become plainly visible to the unaided eye as it gets darker.

Mercury at Greatest Eastern Elongation:  Mercury will be well-positioned in the western sky from March 6-14. During this time Mercury will set about 1-1/2 hours after sundown.

Mercury on March 9th:  This was absolutely the best observation of Mercury that I have every made. Get it while it's high! Gary A. Becker digital photography...

Mercury on March 12th was graced by a two and a half day old moon. Greatest eastern elongation occurred at 1 p.m., EST, six hours earlier. Gary A. Becker digital photography...

447    MARCH 13, 2005:   Inequality on the Equinox

For the East Coast, March may have started out cold and windy, but there is no mistaking the warmer feeling of the sun and the longer days. Regardless of the outdoor clime, spring arrives on Sunday, March 20 at 7:33 a.m. EST. Every equinox, I get e-mails from observant folks who look at the times of sunrise and sunset for the equinox and notice that indeed the day is longer than the night on the first day of spring. It is not a mistake. My astronomy software program says that for Allentown, sunrise on the 20th will occur at 6:05 a.m. and that sundown happens at 6:14 p.m. That’s nine extra minutes of sun. The switch actually happens between March 16th and the 17th. On March 16th for Allentown, the sunrise and sunset happen at 6:11 a.m. and 6:09 p.m. respectively, while on the 17th, sunrise is at 6:09 a.m. and sunset is at 6:11 p.m. Perhaps it would be best to try the spring egg balancing challenge on these dates instead of the Vernal Equinox, March 20th. The nemesis to all of this inequality on the day of equality is something called astronomical refraction. As the light of a star or the sun enters the Earth’s atmosphere from space, it is bent or refracted in such a way that the observer sees the object higher in the sky than it actually is. The effect is greatest for objects on the horizon and nonexistent for bodies directly overhead. The setting or rising sun is elevated by more than half a degree, making the period of time that the sun is above the horizon longer than the period of time it is not on the date of the Vernal Equinox. In fact, astronomical refraction is also responsible for giving the sun its squashed appearance when setting. The lower solar limb is elevated more than the upper limb, flattening the solar disk into this familiar setting posture.

Mercury on March 14th:  It just cannot get any better than this. Mercury was as distinctly visible to the unaided eye as it is in this 7:10 p.m. telephoto image taken from Coopersburg, PA. Mercury was easier to see on March 14, than it was on March 9. Gary A. Becker digital photography...

Mercury on March 16th:  Still bright, but definitely fading, Mercury should remain visible for four or five more days. This picture was taken at 7:15 p.m. at a magnification of approximately two. Gary A. Becker digital image...

448    MARCH 20, 2005:   Calendar Maker

What if all civilization as we knew it came to an abrupt end? No electricity! No computers! No Wegman’s! No Government! After an initial period of chaos in which probably most of us would perish, the survivors would have to get down to the basics: food, shelter, and clothing. I could, at first, imagine close-knit gangs of people roaming the countryside in a hunting and gathering kind of mode. Hopefully, someone would eventually consider farming. That activity would foster the beginning of some type of reorganization. It would necessitate the formulation of a calendar, and that calendar would ultimately be based upon astronomy. Such a calendar might involve marking the sun’s changing position along the horizon at sunrise or sunset, or measuring shadow lengths cast by the sun at noon when they are at their shortest for the day. The observations would involve a keen sense of scrutiny and the ability of the viewer to note the rhythmic cycles of the seasons, not based upon the vagaries of the weather, but upon the consistent and predictable aspects of celestial motions. Eventually, a calendar would emerge, and through trial and error, planting and harvesting cycles would be reestablished. During the next few weeks we have one of the best chances during the year to become sun watchers and see these changes firsthand. If you have a clean shot at sunrise or sunset from a window in your apartment or home, mentally note the sun’s position with respect to foreground and background objects on the next clear day. Revisit your observation about one week later. You’ll be amazed at the change. In a year’s time the sun will come galloping back to repeat the same rise position of a year before. Suddenly you will have become a calendar maker

449    MARCH 27, 2005:   Saving Daylight

On April 3rd, we will jump ahead to Daylight Savings Time. We really won’t be saving any daylight, just readjusting the time period when the sun is visible so that it more equally balances the time when we are awake. In actuality, we assume the Standard Time for the time zone immediately to our east, which for us is Atlantic Standard Time. For the Lehigh Valley, sunrise jumps ahead from 5:41 a.m. to 6:41 a.m. That’s a good thing for me because the light of dawn has really begun to cheat my limited sleeping hours in a big way. By Friday, the sun rises about the time that my alarm goes off. Because most of us are either asleep or at the very least, going about our morning routines as if we were asleep, it really does appear as if we have gained an extra hour of daylight. For Allentown, sundown on April 3 will be at 7:28 p.m. instead of 6:28 p.m. Keep in mind that Daylight Savings time commences at 2:00 a.m. Standard Time which immediately jumps to 3:00 a.m. Daylight Savings Time. There is no 2:00 a.m. to 3:00 a.m. interval on this morning. So even though the clocks have sprung ahead, if we rise at our normal time, we are actually getting up an hour earlier because we have lost an hour’s worth of time. If this sounds confusing, then move to Arizona or Indiana, where for the most part, Standard Time holds sway all year. American Samoa, Hawaii, Puerto Rico, and the Virgin Islands also do not adhere to these time altering measures. If I were the master timekeeper, I would decree a double dose of daylight savings for the summer months when school is recessed. Sundown would happily occur around 9:30 p.m. and I could sleep late every morning. By now, you must know that I’m just a teacher who wants to catch up on some much needed R and R.