StarWatch: Moravian College Astronomy

StarWatch for the greater Lehigh Valley

DECEMBER 2007

DECEMBER STAR MAP | STARWATCH INDEX | MOON PHASE CALENDAR

Print Large Sky Charts For 9 p.m. EST: NORTH | EAST | SOUTH | WEST | ZENITH

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589 DECEMBER 2, 2007: Digital Astrophotography Explosion: It has been 10 years since I began taking images with digital cameras, and nine since purchasing my first, a Kodak 260. It was basically a point and shoot device with a manual override. Along with my Kodak 290, I started recording astronomical events during twilight and began to realize that the digital revolution would one day sweep emulsion photography into extinction. An Olympus D20N followed, and with it, I could record stars and the Milky Way. It took a dark frame, an image of the noise of the chip, and subtracted it from the light frame, reducing the graininess (pixilated nature) of the photograph still further. Then came Canon’s quiet CMOS chip packing 8.2 million pixels of photographic resolution and extended chip sensitivity in the D20 cameras which I purchased. It also boasted high quality interchangeable lenses which made it much more of a system than a camera with a permanent lens like the D20N. Focusing was a problem because there was no live view feature, and dust getting on the sensor screen during lens changes posed additional troubles for imaging. Now Canon has released its new D40, a 10.1 megapixel wonder with a less noisy CMOS chip, a three inch viewing screen, a live view mode with 5x and 10x magnifications, and a sensor that vibrates, shaking off unwanted dust every time the camera is turned on or off. I’ve been in astrophotography “pig heaven” since buying one in late September. Over the past several months I’ve been snapping away, shooting at a magnification of 12.8x, but focusing the image in the live view mode at nearly 130x. If the proof is in the pudding, then look at the images that I’ve taken from light polluted Coopersburg in the Oct., Nov. and Dec. online StarWatch articles. I’m just blown away.

590 DECEMBER 9, 2007: Week of the Geminids: It’s December. The Holidays are fast approaching, and so is the annual Geminid meteor shower, the best shooting star spectacle of the year. Meteors will be most abundant this Thursday evening through dawn Friday, and will appear to be radiating from near the bright star Castor in the constellation of Gemini the Twins. See the online map found with this week’s StarWatch at the URL below. Most casual observers are aware of Perseid meteors that each year fill the sky with glitz and glitter during the second week of August, but are unaware that the Geminids can produce double the action. In fact, in exceptionally dark locales far from the light domes of cities, as many as 200 Geminids have been reported in just one hour of viewing. The handicap for December stargazing is the preparation for coping with the cold weather that usually accompanies a clear night. Keeping your head, hands, and feet toasty is essential to your enjoyment of this event. Cloudy and partly cloudy weather is also in greater abundance near the end of the year and, of course, the entire event can be spoiled by an overwhelmingly bright moon. This year, a skinny waxing crescent moon sets shortly after 8 p.m., about the same time that Gemini is high enough in the east to begin making useful observations. Finding Gemini before midnight will never be easier because orangey Mars, the brightest celestial object after moonset, will lie at the foot of Castor, just 15 degrees above and to the right where Geminid meteors will appear to radiate. If you can handle the cold and sleep deprivation, the last three hours before dawn on Friday morning should prove to be the best. From the suburbs, rates of 30-60 meteors per hour are realistic. And just think of how heavenly that warm shower will feel after you drag your numb body indoors at 6 a.m.

591 DECEMBER 16, 2007: Plunge to Winter: I just popped inside from a brief sojourn with Comet Holmes. It’s still there above Mirfak in Perseus the Hero, a hazy, nebulous blob with a slight elongation away from the sun. This was the first clear evening in about a week. What a change since those more temperate times of early to mid-November, when clear days spilled into starry nights one after the other, and I could go outside with just a light jacket or sweatshirt to photograph Holmes. We have finally made the transition into winter, with cloud-filled nights and snowy forecasts bearing bleak testimony to the long path that we must traverse before the warmth of the May sun invigorates us again. Although high sun does not occur until the summer solstice about June 21, the highest summer temperatures are not confronted until late July. Likewise, the low sun of winter solstice which transpires on Saturday at 1:10 a.m. EST only foreshadows the coldest time of the year, usually about one month afterwards in late January. The Earth’s seasonal temperature lags behind the dates of high and low sun, just like the day’s high temperature occurs during mid-afternoon, several hours after high sun. During the period of time surrounding summer solstice when the sun’s energy is most direct, mid-latitude climes continue to absorb more energy than they release. Only when absorption and radiation are in equilibrium in late July are the highest temperatures achieved. Likewise, we retain the heat of summer deep into the fall season, even though the land is radiating more energy than it is receiving. Novembers often begin with a false sense of hope that maybe the big chill has taken a holiday; but then the big plunge into winter occurs, so that by early December, “Frosty’s” return is assured. Let it snow! Let it ice! Let it sleet! Happy Winter!

592a DECEMBER 23, 2007: Stellar Celebration: He was born six weeks premature at 2 a.m. Christmas day. There was a bright light in the sky at the time of his birth. He never knew his father. Through his intellect and perseverance, he was destined to change the thinking of humankind. Any guesses? If you’re thinking of Christ, guess again. It was the great English physicist, Isaac Newton, born under the light of a full moon in the tiny hamlet of Woolsthorpe, Lincolnshire, England in 1642 (Julian Calendar). Newton’s father, also named Isaac, had died several months earlier. Among many spectacular contributions, Newton quantified the force of gravity, showing how Earth’s gravitational field could attract an object near its surface as well as keep the moon in its orbit around our planet. We needed nothing more than Newtonian mechanics to send Neil Armstrong and Buzz Aldrin to the moon’s surface and return them safely to Earth just barely 300 years after Newton conceived the concept of universal gravitation. Over England and for us this Christmas Eve, the moon will be one day past full. In addition, the brilliant stars of the winter group of constellations, Orion the Hunter, Taurus the Bull, Canis Major and Minor, the Big and Little dogs, and Gemini the Twins will be on the rise in the east and southeast. So there will be no scarcity of bright lights in our sky this week to herald our celebration of the birth of the Messiah. The planet Mars, which does play a part in one theory to explain the Star of Bethlehem, will also be at opposition to the sun along with the full moon on the eve of Christmas Eve, tonight. Look for the moon around 9 p.m. EST and just below it will be orangey Mars. Binoculars will enhance the enjoyment of this observation by allowing the viewer to move the moon out of the field of view while keeping Mars visible. Happy Holidays!

592b DECEMBER 25, 2007: Stellar Celebration: The Christmas Season began because of Christ’s birth, and what signaled that event was but a star. Whatever it was, it blazed forth in beauty and majesty in the heavens. It was a beacon, a guidepost to a momentous event which changed the course of human thought and history. And so are the same stars and planets that were visible to us some 2000 years ago on that first Christmas. They still are present in all of their wonder, a tangible reminder of how constant and reliable the heavens are to us. The brilliant stars of the winter group, Orion the Hunter, Taurus the Bull, Canis Major and Minor, the Big and Little dogs, and Gemini the Twins will be on the rise in the east and southeast during the early evening hours of late December and January. There will be no scarcity of bright lights in our sky this week to mute our celebration of the birth of the Messiah. In addition, the planet Mars, which does play a part in one theory to explain the Star of Bethlehem, is now opposite to the sun and visible in the sky all night. Other than the waning gibbous moon, orangey Mars is the second brightest object in the evening sky. Look for Mars due east by 9 p.m. On a still, dark winter’s eve, Mars hangs like a ruby against a backdrop of blue and white diamonds, their atmospheric scintillations calming the soul. They seem to whisper thoughts of grandeur, inspiring us to achieve greatness, placing our lives into perspective. During this season of light, let us open our hearts, not only to the astronomical significance of what we are seeing, but also to the innate beauty that is spread above us. On frosty winter evenings, remember the place of the stars in their crisp tapestry of brilliance overhead. They are not aloof, but invite all of us to participate in the great cosmic mysteries that remain to tantalize us at the edge of infinity. Byline should read Gary and Susan Becker

593 DECEMBER 30, 2007: Tuttle to Tickle and Tease: By gosh, there is another comet in the sky. Unlike Comet 17P/Holmes which exploded unexpectedly on October 24 to become one million times brighter, Comet 8P/Tuttle has been anticipated for years, and it seems to be behaving quite nicely. Originally discovered by French observer Pierre Méchain (1744-1804) in 1790, the comet was not seen on subsequent returns until its recovery in January of 1858 by Harvard astronomer, Horace Parnell Tuttle (1839–1923). Since then, it has been viewed on every return except one (1953). Tuttle swings around the sun in only 13.6 years, and it possesses a steep 55 degree inclination to the plane of the solar system, so its orbit is very stable. It is a small, sun weary comet having exhausted much of its volatile materials on countless passages around Sol. Its returns are usually not very favorable, but this time is different because the comet is not only well-placed with respect to the sun, but it is traveling closer to the Earth than at any time since it has been observed. On January 2, 2008, 8P/Tuttle will pass just over 23 million miles from us, besting its 1790 discovery distance by 12 million miles. Furthermore, it will be high in the west in a moonless sky during the evening hours of early January. You will need to be in a suburban or rural setting and have binoculars or a telescope to see it. Through binoculars, Tuttle will appear as a small but easily discernable fuzzy spot, perhaps with a slight elongation away from the sun. Averted vision will produce a brighter view. The map found at the URL below in “this week’s StarWatch” will aid in locating 8P/Tuttle. Use the position of the Great Square of Pegasus, the extension of stars that form Andromeda, the bright star Hamel in Aries, and the star Alrescha in Pisces to provide anchors for easier location.

[December Star Map]

[December Moon Phase Calendar]