JULY  2005

JULY STAR MAP | STARWATCH INDEX | MOON PHASE CALENDAR

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463    JULY 3, 2005:   "We Interrupt Our Program..."

There has been a persistent and false rumor circulating throughout the cyber world that Mars is going to be exceptionally close to the Earth by the end of summer. In fact, the distance quoted, 34.6 million miles, is exactly the same as the Red Planet’s approach to us on August 27, 2003 when Mars was at its closest position to the Earth in as many as 60,000 years. With the Hollywood blockbuster, “War of the Worlds,” giving us a fresh insight into H. G. Wells’s classic of aliens (not Martians) invading the Earth, this rumor may have had a premeditated origin. That’s just my guess. Regardless of this hypothesis, all is not lost. Mars will be making a very favorable encore visitation into our evening skies this autumn. The ironic part of Mars’s return is that it will be at its closest position to the Earth exactly 67 years to the day after the infamous Orson Welles Halloween Eve Mercury Theater radio spoof of “War of the Worlds.” On Sunday, October 30, 2005 at 10:00 p.m., EST, Earth will be closest, just over 43 million miles from the Red Planet. Welles’s broadcast began on Sunday, October 30, 1938, just two hours earlier. Mars will be over eight million miles farther from the Earth than in 2003, but it will climb twice as high into the sky. During Halloween week, orangey Mars will be high in the south by midnight, visible easily from any urban locale. Telescopically, Mars will appear just a tad bit smaller, but since there will be less turbulent atmosphere to penetrate, Mars’s magnified image should appear clearer than in 2003. Pictured against the backdrop of “War of the Worlds,” you can bet that I too will be scanning the Red Planet with my telescope for those same flashes of blue light so vividly described to the world by reporter Carl Phillips in 1938.

464    JULY 10, 2005:   Mercury, Venus Still Hanging Tight

After nearly four weeks Mercury and Venus are still hanging tight, low in the western sky about 40 minutes after sundown. Even if your horizon is only moderately clear, you should be able to spot Venus easily about 30 minutes after sunset. If your western horizon is optimal, Venus will appear about one fist height above the horizon. Clench your hand into a fist and hold it in front of you at arm’s length with the thumb on top. Venus’s one fist height corresponds to an angle of approximately 10 degrees. I guarantee that if you try this little angle measuring technique, you’ll get newfound respect from your curious neighbors. After all, no one ever messes with a crazy person, do they? But then, have your binoculars handy to help you locate Mercury. Haze, which is always thickest nearest to the horizon, will probably render Mercury invisible to the unaided eye. During the entire week, Mercury will appear below Venus at increasingly greater distances. However at all times, the two planets will still nest within the same binocular field of view. Mercury and Venus have been in close association with each other for the past month, and the reasons are straightforward. During this time interval, Venus has been on the far side of the sun relatively distant from Earth, so its apparent motion in the sky has appeared to be slow. Faster moving Mercury zoomed into position as it also came around the backside of the sun, but then its apparent motion slowed as it rounded the far end of its orbit and began to approach the Earth. It’s analogous to a horserace. As the steeds round the far end of the track, their forward motion seems to slow because they are approaching the observer. The race is almost over, however, and Mercury, the winner, will be gone by next week.

465    JULY 17, 2005:   Surf's Up

Over the last week the moon has been approaching its full phase, while at the same time, it has also drawn closer to the Earth. On Thursday at 7 a.m., EDT, the moon will be full. Nine hours later, it will be at its closest position to the Earth. A new or a full moon, coupled with a moon near to the Earth, is a great recipe for high tides. Here’s why. The moon swings around the Earth in an oval-shaped orbit, approaching to just over 221,000 miles from our planet and receding to a distance of just under 253,000 miles. The time period between two successive closest or farthest lunar points is called the anomalistic month and it is 27.56 days in length. The average period between two full moons is 29.53 days. It is like having two drums beating at two distinct measures. They sound discordant most of the time because they are out of phase. But every so often the beats come together, and their combined effects are amplified. Likewise, the tides are amplified when the moon is full, and at the same time, near to the Earth. Both the sun and the moon pull on the oceans to create the tides, but the moon has nearly 2-1/2 times the advantage. That’s because tidal forces are affected more by distance than they are by mass, and the moon is indeed our closest neighbor in space. When the moon and the sun line up at a new or a full phase, the tidal generating powers of each is added, making the variation between high and low tides the greatest. With the tides, the ocean waters (and land) are actually pulled closer to the moon. In the open seas, tides rise between one and two feet, but near shorelines, and because of topography, the sloshing effects of the tides can become as great as 50 feet. All of this is enhanced even more when the moon is near to us at the same time. Surf’s up!

466    JULY 24, 2005:   Meteor Season Begins

Up until recently, lightning bugs have been illuminating the backyard at night, but now it’s time for the meteors to takeover. No, these shooting stars will not be as pervasive as summer’s fireflies, but the din of meteoric activity will be on the rise for the next three weeks as nearly a dozen minor summer events wax and wane against the backdrop of shooting stars resulting from the Delta Aquarids and the famous Perseids. Meteors, the flashes of light that result when small sand grain-sized particles rip through the atmosphere and cause it to glow, originate from the dross released by comets as they orbit the sun. Both the Delta Aquarids and Perseids occur under favorable lunar circumstances; a fat waning crescent moon for the Aquarids and a first quarter moon for the Perseids. The Delta Aquarids have a northern and a southern component, and it is the southern branch which produces the highest rates. Expect to see between 5-10 meteors per hour from rural locations. The weekend hours just before dawn should yield the greatest activity, but realize that meteors from this stream will be visible all week. Lie on a tarp or reclining chair with your legs pointing south and simply look straight up. Meteors from the Delta Aquarids will appear to fan out above a bright star low in the south called Fomalhaut. If your southern horizon is obscured by trees, note the four stars of the large Great Square of Pegasus which will be high in the south by 3 a.m. Twice the distance below the two stars which form the right side of the square, in the southern part of the constellation Aquarius, is the general location from which the Delta Aquarid meteors radiate. Read ahead at the URL below to learn more about observing techniques, etiquette, and the Perseids.

467    JULY 31, 2005:   Make the Perseids an Event

The Perseid meteor shower climaxes on the morning of August 12. I have traveled, sometimes thousands of miles, to watch their bright flashes tear through a dark sky. Probably the most memorable evening was spent at a campground near Jefferson, New Hampshire. I purposely staked my tent in a wooded area, which had a large clearing, to get far away from the hordes of campers that had filled the KOA to capacity. My observing buddy, Adam Jones and I got settled in about 11:00 p.m. for an all-nighter under clear but dewy skies. We simply reclined on air mattresses and nested ourselves into sleeping bags with pillows to help prop our heads. Then we covered our bags and gear with a thick plastic painter’s tarp and began to watch. It took just a few minutes before the first bright meteor signaled its arrival, and our resultant exclamations echoed along with scores of other skyward-looking participants. The sheer number of campers watching the sky surprised me. For several hours, well past midnight, clusters of cheers and shouts kept echoing across the landscape, keeping us company whenever a bright meteor flashed. So what’s the best recipe for an enjoyable Perseid evening? Make it an event. Observe with friends. Make sure you’re warm and comfortable, and, if necessary, have some protection from the dew. Start observing after midnight. Bring along a warm caffeinated beverage and some munchies to sustain the spirits. If you want to do science, then count Perseids in 10-minute intervals, with no more than a 10 minute break each hour. Observe meteors in the darkest part of the sky, which is usually overhead. Make sure that each observer records his or her own data. For more information, check out www.imo.net/visual/major01.html, or read ahead at www.astronomy.org.