StarWatch for the greater Lehigh Valley



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[Moon Phases]
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Status Current Moon Phase
902    DECEMBER 1, 2013:   Comet ISON Gone; Lovejoy Prevails
Comet ISON disintegrated as it approached its closest distance to the sun on Thanksgiving Day—puff—gone. Even though the Great Comet of 2013 no longer exists, there are three other interlopers gracing the predawn skies of the northern hemisphere. It just seems to be “raining comets” these days, a much better situation than raining or snowing if you’re into astronomy. Two of these comets are strictly binocular, 2P/Encke and C/2012 X1 (LINEAR), while the third, C/2013 R1 (Lovejoy), should be a faint naked eye/easy binocular target this week, moving from Bootes, the Bear Driver, into the star pattern of Corona Borealis, the Northern Crown. An online map is available. Comet Lovejoy was discovered on September 7 by Australian, Terry Lovejoy, who resides about 15 miles to the southeast of Brisbane. During the past several weeks his comet has proven to be a real overachiever. Predicted to be barely binocular at it brightest, Lovejoy, just like Comet ISON, underwent an outburst in brightness in mid-November that propelled it to faint naked eye visibility. Unfortunately, the gibbous moon entered the picture, snuffing out any chance to see the comet easily. Now that the moon has faded, Comet Lovejoy holds the undisputed title for “Comet to See” since ISON no longer exists. View Comet Lovejoy between 4:00-5:30 a.m. when it is highest in the sky. During the first week in December, look NE at 5 a.m. to find the Big Dipper, and follow the arc of the Dipper’s handle to a bright orangey star, Arcturus, in the constellation of Bootes. Scan to the left of Arcturus, across the constellation of Bootes about four binocular fields, and you should come across a fuzzy looking object with a stubby tail. That will be Comet Lovejoy. If you are observing from a rural locale, lower your binoculars while keeping your gaze fixed in the same direction to see if the comet is visible to the unaided eye.

[ISON Rounds Sun]
Comet ISON reached perihelion on Thanksgiving Day at about 1:45 p.m. EST. As it approached the sun, the comet seemed to fade and disintegrate prompting me to rewrite my StarWatch article for December 1 with the first sentence saying “Comet ISON disintegrated as it approached its closest distance to the sun on Thanksgiving Day—puff—gone.” Most astronomers thought that it was a goner, but several hours later Comet ISON emerged somewhat disheveled, but back from the dead. Now astronomers are asking if there is enough material left in the comet to allow it to still “strut its stuff” in our morning sky over the next several weeks. No one seems to know the answer as of November 29. I have now changed my StarWatch article back to its original content and I am waiting like everyone else for the verdict. Images from SOHO, the Solar and Heliospheric Observatory...

[comet Lovejoy]
Comet Lovejoy sprouts a nice tail even under the light of a third quarter moon. Originally predicted to be only a telescopic object, Lovejoy suffered an outburst which brought it virtually to naked eye visibility from rural locals; however, the brightness of the gibbous moon spoiled the show. Now that the moon is waning and past third quarter, it will be interesting to see how a darker sky affects Comet Lovejoy's visibility. The limiting magnitude of this image is about +12.5. Lovejoy was captured with a Canon 60D camera using a 70-200mm Canon zoom lens at an EFL of 160mm. The camera and lens were fixed to a German equatorial mount. The picture was exposed for 60 seconds at F/3.5, ASA 800, with a sensor temperature of 4000 K. Image by Gary A. Becker on November 25 at 5:30 a.m. from Coopersburg, PA...

[comet Lovejoy Map]
Lovejoy map by Gary A. Becker using Software Bisque's The Sky...

903    DECEMBER 8, 2013:   What Happened to Comet ISON?
The last 10 days have been filled with the anticipation of a great comet gracing our morning Yule sky, something that has not been seen in the northern hemisphere since the back-to-back shows created by Comet Hyakutake in 1996 and Comet Hale-Bopp during the spring of 1997. However, comets are like cats; they have tails and do exactly as they want. As I watched the images of ISON sent from SOHO, the Solar and Heliospheric Observatory, a beautifully formed comet with gas and dust tails approached the sun, but within several hours of its closest passage on Thanksgiving Day, it became evident that ISON was in big trouble. The 5000 degree F. temperatures, which the comet’s small nucleus experienced, vaporized much of the ices and the dust. Still not everything was gone, and ISON emerged several hours after perihelion as an amorphous remnant of its former self. Then to the cheers of everyone, the comet began to brighten and hopes soared that ISON might yet regain its glory and become the great comet that it was expected to be. Evidentially, there was still some leftover ice, but in less than a day, those expectations were dashed, when the comet began to fade rapidly. What was seen by SOHO was an expanding cloud of debris blown away from the comet’s nucleus as it disintegrated into billions of tiny pieces after passing the sun the previous day. The lesson that can be learned from Comet ISON is that astronomy is still the science of the unexpected. It is full of exhilarating surprises, like a supernova, a vivid aurora, or a bright fireball that lights up a Russian sky. Astronomy is also filled with deep disappointments, like a cloudy night during a spectacular meteor storm, equipment that malfunctions at a critical moment, or a great comet like ISON that fizzles into mediocrity. It is probably the frustrations that translate into making the successes seem so sweet. Photos of ISON’s demise are online.

[The Demise of ISON]
Comet ISON’s rapid disintegration after its perihelion passage on Thanksgiving Day is aptly shown in this SOHO, Solar and Heliospheric Observatory space photography composite. Its breakup was a great disappointment to the astronomical community which predicted the possibility of a great comet once it rounded the sun.

904    DECEMBER 17, 2013:   Finger Angles: A “Handy” Device
The day or night sky that we see above our heads is called the celestial sphere, and as such, measurements made against it must be realized as angles—degrees, minutes, and seconds of arc. The sky at your local horizon is a circle which contains 360 degrees. The angular measure of an arc extended upward from the horizon and passing through the zenith to the opposite horizon equals 180 degrees. You can’t say with any accuracy that the bright meteor which you have just seen was about “two feet in length” because there is no conversion between feet and degrees. Besides, who carries a ruler and flashlight with them in their hip pockets? However, with angular measurements, you are always carrying a “handy” pocket device which will allow for relatively accurate results. It is your fingers and fist held at arm’s length that can do the trick. As an example, if you make your hand into a loose fist with your thumb on top, the angular distance that your fist will subtend at arm’s length is about 10 degrees. Nine fists should make it from the horizon, the horizontal, to the zenith, the point directly over your head. You can stack one fist on top of the other, but just make sure that the fist that is being stacked upon does not “hammer down” the fist on the bottom. The lower fist must remain stationary, while the other fist is being put on top of it. In addition, you can spread you thumb and pinky finger into a wide “V” or rabbit ears with the three middle fingers folded down to obtain an angular measurement of 20 degrees, as wide as the hand can be stretched. Again, your fingers would be at arm’s length. Hold your three middle fingers side by side to obtain an angular measurement of just five degrees. Finally, the pinky held at arm’s length represents an angle of just one degree. Try measuring the angular size of that great big full moon in the sky with just your pinky finger, and I guarantee you’ll be amazed by the result.

[Finger Angles]
Giving the Finger to Astronomy is not as bad as it may seem. Here are a set of handy angles created by fingers and hands to measure the angular separation of objects in the sky. Keep in mind that these angles are only approximate. Not all hands and fingers are created equal.

905    DECEMBER 22, 2013:   Two “Stars” Light the Yule Sky
The Star of Bethlehem has long intrigued scholars, but because of its distance in time, it may be a problem that will never be solved to the satisfaction of everyone. Two astronomical hypotheses have been favored. The first is a triple conjunction (coming together) of the planets, Jupiter and Saturn, which played out during the years 7 to early 6 BC. The second is an extremely close conjunction of Venus and Jupiter which happened in June of 2 BC. And then there are the Magi who saw the star in the east, or as many scholars have interpreted, while they were in the east, Persia, since historians have generally considered the Wise Men to be Zoroastrian priests who originated from the modern country of Iran. Both theories favor a more westerly view for the culminating aspects of the star. I personally favor the triple conjunction supposition, but that is not the premise of this article. It is really to alert everyone that this Yuletide Season hosts a beautiful “Star of Bethlehem” in the east as well as an even brighter “Star of Bethlehem” in the western sky. I have been watching the “star” low in the west for the past six months, but because of Christmas, it has taken on a whole new meaning. It is none other than the planet Venus, currently at its greatest brilliancy, easily bright enough to cast shadows on the ground if you are in its presence on a snowscape in a rural locale. View Venus low to the horizon in the SW about 30 minutes after sundown. The second “star” is indeed low in the east around 8 p.m., and it is also at its greatest brilliancy. Jupiter cannot be missed rising with the stars of Gemini the Twins. To Jupiter’s immediate left are the bright luminaries of Castor and Pollux, and to Jupiter’s right the glittering stars of Orion the Hunter. With snow blanketing the Northeast, this may be one of the most politically correct Christmases that we have had in quite some time. Happy Holidays during this season of heavenly light.

906    DECEMBER 29, 2013:   Winter Group: Here Today, Gone Tomorrow
If you are a regular reader of this column, then you know that winter is my least favorite season. I am definitely a summer guy who enjoys observing the tapestry of the heavens with minimal encumbering apparel. One aspect of winter, however, which does afford me pleasure is the early evening arrival of the winter group of constellations: Auriga the Charioteer, Orion the Hunter, Taurus the Bull, Canis Major and Minor, the big and little dogs, and not to be forgotten, the Gemini Twins with bright Jupiter currently tucked in their midst. We are definitely cheated from a longer view of this group. When they do begin to appear earlier in the evening, their time of visibility is cut short by two different phenomena. First is the revolution of the Earth around the sun which causes all celestial bodies to rise about four minutes earlier each evening. Second, from winter through spring, the sun is migrating northward, causing the length of daylight hours to increase. Compound these changes over the course of a month, and the star patterns which are seen at 10 p.m. at the beginning of January are the same set of constellations which will be visible at 8 p.m. by early February, and 6 p.m. by March 1. However, by early March, the sun will be setting around 5:50 p.m., and it won’t be completely dark until nearly 7:30 p.m. By mid-April the winter group is setting into the western twilight, gone until the beginning of next year. Just the opposite scenario happens in the southern hemisphere where Orion and company are seen in the summertime, and the stars linger because the southern hemisphere is headed towards winter and longer nights. I have had that experience in Australia. There is just one small problem. What is familiar to us in the northern hemisphere is upside down, Down Under. Believe me; Aussie skies are really hard on the head, but they glitter compared to our more austere skies of the north.

[December Star Map]

[December Moon Phase Calendar]