****************************************************** Abrams Planetarium SKYWATCHER'S DIARY December 1996 ****************************************************** The Skywatcher's Diary for December 1996 has been prepared by Robert C. Victor. Credit to Abrams Planetarium, Department of Physics and Astronomy at Michigan State University, together with mention of our Sky Calendar, would be appreciated. A sample back issue of Sky Calendar is available over the Internet. It can be viewed via a World-Wide Web browser such as Netscape or Mosaic, directly at URL: http://www.pa.msu.edu/abrams/skycal.html If you would like a printed sample, send a long, self-addressed stamped envelope to: December Sky Calendar Abrams Planetarium Michigan State University East Lansing, MI 48824 Each month, the Department of Physics and Astronomy at Michigan State University also makes Skywatcher's Diary available over the Internet. It can be accessed via a World-Wide Web browser such as Netscape or Mosaic, directly at URL: http://www.pa.msu.edu/abrams/diary.html The Skywatcher's Diary is also available via anonymous ftp at: www.pa.msu.edu in the directory /pub/swd ****************************************************** Moon, Planets, and Comet Hale-Bopp in December Morning Planets: Brilliant Venus rises ahead of the Sun, by 2 to 2-1/2 hours on December 1, and just over 1-1/2 hours on Dec. 31. One hour before sunrise, Venus is low in SE, while reddish Mars is high in S to SSW. On Christmas morning, Venus will lead the eye to Antares emerging 6 degrees to its lower right, and Mars will be midway between Regulus and Spica, 27 degrees from each. For a related astrophotography project, point your Web browser to: http://www.pa.msu.edu/abrams/mars97retro.html A waning crescent Moon forms pretty morning groupings with planets and stars December 3-9. Remember that morning events in the Diary are described on previous day. Evening planets: Bright Jupiter is sinking into SW twilight glow; during Dec. 1-31 it sets over 2-1/2 hours to barely one hour after Sun. Mercury is a fairly easy target for binoculars to lower right of Jupiter at dusk in December's 2nd and 3rd weeks. Look for Mercury 14 degrees to Jupiter's lower right Dec. 8, shrinking to 4 degrees on Dec. 21-22. A young crescent Moon passes these two planets on Dec. 11 and 12. Saturn is in SE to S at dusk; a telescope shows the rings tipped only 3 to 3.5 degrees from edgewise, the narrowest view of the ring system we'll get until the approach of their next edgewise aspect in 2009. The Moon appears near Saturn on evenings of Dec. 16 and 17. The Moon has a close encounter with Aldebaran in the late afternoon or evening of December 22. The exact circumstances of their meeting depends on your location. From some areas, the Moon will occult, or cover, Aldebaran. A map showing the southern limit of the region where this occultation can be observed appears on page 77 of January 1996 Sky & Telescope. In the minute beginning 5:25 p.m. EST, the southern edge of the Moon's "shadow" (considering Aldebaran as the light source) passes through southeastern Michigan -- southern Hillsdale, central Lenawee, northwest Monroe, southeast Washtenaw, and southern Wayne Counties. In the roughly 2-mile-wide "graze zone" passing through those counties, an observer equipped with a telescope would see Aldebaran alternately disappear behind lunar mountains and reappear in lunar valleys. Seen from north of that line in our state, Aldebaran will be hidden by the Moon for several minutes; the farther north you are, the longer the star will be hidden. Seen from south of that line, the Moon narrowly misses the star. For additional information, see Website for International Occultation Timing Association, http://www.sky.net/~robinson/iotandx.htm and Dec. 22 in Skywatcher's Diary below. Comet Hale-Bopp may attain first magnitude in March-April 1997. During December 1996, it may brighten slowly to mag 3.5 (use binoculars). Until it sinks into twilight glow late this month, best time to see comet remains just before end of twilight, or about 1-1/4 hours after sunset. Best dates this month to observe Hale-Bopp: Dec. 1-17; the earlier this month you look, the higher and easier it will be to find. For Dec 1-6, see box on our November Sky Calendar showing positions until Dec 6. For Dec. 7-17, see our December Sky Calendar for a chart plotting the comet's position on those dates. The Comet may brighten from mag 4.5 to 3.5 in December. As comet nears conjunction 28¡ due N of Sun Dec 30, it gets very low in WSW to W at nightfall. If its brightness follows this prediction, it will become hard to see. To find Comet Hale-Bopp one and a quarter hours after sunset, begin with Summer Triangle: Vega, the Triangle's brightest star, well up in WNW; Deneb, atop the Triangle, above Vega; and Altair, the south point of the Triangle, in WSW. Next, locate the 2nd-mag star Rasalhague, or Alpha in Ophiuchus, low in W. Marking the head of Ophiuchus the Serpent- bearer, Alpha Oph stands out as it completes a nearly equilateral triangle, 30 to 34 degrees on each side, with Vega and Altair. Dec 7-17: Comet is some 25¡ lower right of Altair and 15¡ left of Alpha Oph. On Dec 26, comet is very low in W, but if unexpectedly bright, could still be seen on that date 19¡ lower right of Altair, and on morning of Dec 31, very low in E 18¡ lower left of Alpha Oph and 11¡ right of Zeta in Aquila. For more on Comet Hale-Bopp, try these Websites: Comet Observation Home Page (JPL/NASA): http://encke.jpl.nasa.gov/ Sky Online's Comet Page: http://www.skypub.com/comets/comets.html Press Info on H-B: http://cfa- www.harvard.edu/cfa/ps/HaleBopp.html ****************************************************** SKYWATCHER'S DIARY: December 1, 1996 - January 13, 1997 Sunday, December 1 On Monday an hour before sunup, Moon is high in SSW and just over half full. Regulus is within 5 degrees to Moon's upper right, and reddish Mars about 15 degrees to Moon's left. Look again Tuesday to see Moon near Mars. One week from today the Moon will pass Venus, the brilliant planet low in ESE to SE. Monday, December 2 An hour before sunrise on Tuesday, Moon is high in south and just under half full. Reddish Mars is 5 degrees to Moon's upper left. If you look before dawn brightens, note 4th-mag star Sigma in Leo about a degree to Mars' lower left. On Thursday morning Mars will pass within half a degree from Sigma. Look daily to follow Mars' motion, now just under half a degree per day. Mars has been in the news lately, with the successful launching of NASA's Global Surveyor on Nov. 6. For more information, visit the Mars Global Surveyor homepage at: http://mgs-www.jpl.nasa.gov/ Although NASA's Mars Pathfinder is planned to be launched today, it will arrive at Mars first, on July 4, 1997. Tuesday, December 3 An hour before sunup on Wednesday the fat crescent Moon is well up in SSE to S, with Mars 9 or 10 degrees to its upper right. Some 27 degrees sunward (lower left) of the Moon is first-magnitude Spica in Virgo. Mars will pass that star on the evening of August 3, 1997. Between now and then, Mars will trace out a looping path among the stars of Leo and Virgo. More tomorrow. For ideas for an astrophotography project demonstrating Mars' motion against the stars, point your Web browser to: http://www.pa.msu.edu/abrams/mars97retro.html Wednesday, December 4 At dawn's first light on Thursday, about 1-1/2 hours before sunrise, the Moon is well up in SE with Mars some 20 degrees to Moon's upper right. Using binoculars if necessary, look carefully within half a degree lower right of Mars for the 4th-magnitude star Sigma in Leo. Spica is within 15 degrees to Moon's lower left, and the 3rd-mag star Gamma in Virgo is 3 degrees to Moon's upper left. It'll be interesting to follow Mars for the next several months. In the morning sky in early February 1997, the brightening red planet will stop 4 degrees short of Gamma in Virgo and then begin to go back toward Sigma in Leo! After reaching greatest brilliance in mid- March when it's also visible all night, Mars will make a tight loop around Sigma Leo in the evening skies of April-May. In late April Mars will resume its normal eastward motion against the stars, finally passing Gamma in Virgo in early July and Spica in early August. Thursday, December 5 An hour before sunup on Friday, find the waning crescent Moon in SE with Spica about 3 degrees to its lower right. Mars is high in S 35 degrees to Spica's upper right. Brilliant Venus is low in ESE to SE, 23 degrees to Spica's lower left. Can you predict where the Moon will appear on Sunday morning? Friday, December 6 An hour before sunup on Saturday, the crescent Moon is in SE with Spica 12 degrees to its upper right and Venus about same distance to Moon's lower left. Don't miss the beautiful close pairing of the two brightest nighttime objects Sunday morning. More tomorrow. Saturday, December 7 Don't miss Sunday morning's pairing of Venus and the crescent Moon! Begin about two hours before sunrise, when they're very low in ESE. For Michigan skywatchers Venus is then just 1.3 degrees to lower right of the Moon's southern cusp, or lower right point of the crescent, and the gap shrinks to 1.0 deg by sunrise and remains the same for the next hour. Wherever you are, watch the Moon's sunward motion relative to Venus. The farther west you are in the U.S., the earlier will be the time of closest approach of Moon and Venus. From the West Coast they're closest as they rise. Sunday, December 8 An hour before sunrise on Monday, the last thin crescent old Moon of the current lunar cycle is a few degrees above ESE horizon, some 12 degrees lower left of brilliant Venus. As dawn brightens Monday, follow the Moon with your unaided eye for as long as you can and record the time you last see it. How many hours and minutes before New will you last see the Moon? New Moon will occur on Tuesday at 11:56 a.m. EST (8:56 a.m. PST). Monday, December 9 Moonwatchers in southern Asia have the best chance to make the last sightings of the very thin old Moon rising shortly before sunrise Tuesday. They'll catch it on ESE horizon about 20 degrees lower left of Venus 30 minutes before sunrise. From eastern China Moon will be nearly 19 hours before New and should be visible to unaided eye. From Karachi, Pakistan Moon will be about 15 hours before New and a naked-eye sighting would set a new record. By the time the Moon rises in the U.S. Tuesday, it's not visible by any means. Tuesday, December 10 The Moon is New today at 11:56 a.m. EST and is not visible this morning or this evening from anywhere in North America. Using optical aid, skilled observers at the Observatory atop Mauna Kea in Hawaii may have a chance to spot the exceedingly thin, short lunar crescent soon after sunset this evening. If they succeed, the Moon will be just over 11 hours past New and just 7 degrees from the Sun, setting new records. A few hours later, moonwatchers in Japan, where the Moon's age will be nearly 16 hours, or in east Asia, or on other islands in the western Pacific have a better chance at being first to see the young Moon on Wednesday evening, Dec. 11 local date. The youngest Moon ever seen was spotted by observers in Arizona on Jan. 20, 1996; see "In Quest of the Youngest Moon," in December 1966 Sky & Telescope, pp. 104-106. Wednesday, December 11 Early this evening, North Americans have their first chance to see the Moon since Monday morning. Shortly after sunset, look for the thin young crescent low in SW. Within half an hour after sunset Jupiter is prominent 15 degrees to Moon's upper left. As sky darkens for another quarter-hour look for Mercury 11 degrees lower right of Jupiter and 7 or 8 deg lower left of Moon (or to Moon's left in Florida). Nearly 1-1/4 to 1-1/2 hours after sunset, as Moon is about to set, look 20 degrees upper right of Moon, 25 degrees lower right of Altair, and 16 degrees left of 2nd-mag Alpha in Ophiuchus for Comet Hale-Bopp. It should be visible in binoculars as a fuzzy patch of about 4th magnitude. For more on Comet Hale-Bopp, try these Websites: Comet Observation Home Page (JPL/NASA): http://encke.jpl.nasa.gov/ Sky Online's Comet Page: http://www.skypub.com/comets/comets.html Press Info on H-B: http://cfa- www.harvard.edu/cfa/ps/HaleBopp.html Thursday, December 12 About 45 minutes after sunset, crescent Moon is in SW with Jupiter 4 degrees to its lower left. Mercury is near horizon 10 degrees to Jupiter's lower right. In five days the Moon will pass Saturn Look nightly. Geminid meteors are expected to be most plentiful tonight and Friday night, from late evening (10:30 p.m.) until first light of dawn. Compared to meteors from most other showers, the Geminids are noticeably slower, entering Earth's atmosphere at a "liesurely" 78,000 miles per hour, versus 159,000 miles per hour for the Leonids in November and 134,000 miles per hour for the Perseids in August. For more information about meteor showers see Sky Online's Meteor Page at: http://www.skypub.com/meteors/meteors.html Friday, December 13 About 45 minutes after sunset, look for Jupiter low in SW about 15 degrees lower right of the waxing crescent Moon. Mercury is within 9 deg lower right of Jupiter. Saturday, December 14 About 45 minutes after sunset, the crescent Moon, about 25 percent illuminated, is in SSW with Jupiter low in SW about 30 degrees to Moon's lower right. Mercury is now another 8 degrees lower right of Jupiter. To Moon's right as sky darkens is the first-magnitude star Altair, forming a nearly equilateral triangle with Moon and Jupiter. As darkness falls, Comet Hale-Bopp is low, just south of due west, and 24 deg lower right of Altair. Sunday, December 15 About 45 minutes after sunset, bright Jupiter is low in SW, with Mercury 7 degrees to its lower right. Mercury is now at its farthest angular distance from the Sun during this evening appearance, 20 degrees. Locate Saturn high in SSE. Tonight Moon appears over three-fifths of the way from Jupiter toward Saturn. Monday, December 16 Moon, just short of half full, stands high in southern sky one hour after sunset. Within a few days before or after half full, Moon viewing is at its best: Binoculars and telescopes show spectacular detail near Moon's terminator (day-night boundary). Tuesday, December 17 Moon is high in SSE an hour before sunset, with Saturn glowing within 3 or 4 degrees to its lower right. With a telescope enjoy the Moon's craters and Saturn's rings, tipped just over 3 degrees from edge-on. Wednesday, December 18 Forty-five minutes after sunset, Jupiter is low in SW with Mercury 5 degrees lower right. Binoculars give fine views of the two planets within the same field until Christmas. The waxing gibbous Moon, two-thirds full, has Saturn 16 degrees to its right. Thursday, December 19 About two hours after sunset, face east to see the rising of magnificent Orion, the Hunter. Reddish Betelgeuse, his bright shoulder, is in the east. Within 19 degrees to the right is bluish Rigel, marking the Hunter's upraised foot. About midway between thes two bright stars lies his belt, consisting of three stars in a nearly vertical line. Friday, December 20 Winter begins Saturday at 9:06 a.m. EST, when the Sun stands directly over the Tropic of Capricorn in the South Atlantic Ocean off the coast of South America. From North America, tonight is the longest night, and Saturday the shortest day. Saturday, December 21 Low in southwest tonight and Sunday, about 45 minutes after sunset, Mercury appears just 4 degrees lower right of Jupiter. As sky darkens, watch for the Pleiades star cluster 9 deg to Moon's upper left, and first-magnitude Aldebaran, eye of Taurus, 12 deg to Moon's lower left. An unusual event involving Moon and Aldebaran will take place on Sunday. Sunday, December 22 Late this afternoon or early evening, the rugged southern edge of the Moon grazes the star Aldebaran as seen along a very narrow track -- only about 1.5 miles wide --from central Missouri to the St. Lawrence River Valley. If you're in that zone looking through a telescope, you can see a "grazing occultation" in which the star will alternately be hidden by lunar mountains -- some as high as 2 miles - - and reappear within valleys on the Moon's edge as our satellite's orbital motion carries it past the star. The "graze path" crosses central Illinois before sunset, northwest Indiana around sunset, southeast Michigan a few minutes after sunset, and into Canada, passing through Toronto. In Michigan, the graze occurs near Hudson at 5:25 p.m. EST, followed within the next minute by locations within a mile or two of Adrian, Milan, New Boston, and River Rouge. The graze moves into Canada at Windsor, Ontario at 5:26 p.m., near London at 5:27 p.m., and through Toronto just after 5:29 p.m. A map of the graze path appeared in January 1996 Sky & Telescope, page 77. If you're located SE of the grazepath, the Moon misses Aldebaran. Seen from NW of the graze path, the Moon will occult (cover) the star; for example, from Chicago, Moon covers star from 4:17 to 4:34 p.m. CST. For more information on this occultation, see the Website for the International Occultation Timing Association, at: http://www.sky.net/~robinson/iotandx.htm Monday, December 23 This is the last evening of the current cycle to observe the Moon just before sunset. At nightfall, about 1-1/2 hours after sunset, look for Aldebaran to Moon's upper right, and Betelgeuse, shoulder of Orion, a similar distance to Moon's lower right. Tuesday, December 24 On Christmas Eve, the Full, Long Night Moon, or Moon Before Yule, rises in ENE within 25 minutes after sunset as seen from southern Michigan. [From southern U.S. the waiting time is shorter.] Two hours after sunset, when Moon has risen higher, look for Betelgeuse 13 deg to right of Moon, and the Gemini twins, Pollux below Castor, about 21 deg to Moon's left. On Christmas morning an hour before sunup, Moon will be in WSW with Pollux and Castor side-by-side above the Moon. Brilliant Venus is in SE with Antares rising 6 degrees lower right. Binoculars help locate the twinking red star. On each successive morning, Antares appears higher, and Venus a little lower. Wednesday, December 25 Tonight Moon rises in ENE about 1 to 1-1/4 hours after sunset. As it rises, look for the Twins, Pollux below Castor, to Moon's upper left. An hour before sunup on Thursday, Moon is in west, about midway between Pollux and Procyon, the Little Dog Star. Thursday, December 26 Three hours after sunset, Moon is in ENE with Procyon 12 degrees right. An hour before sunup on Friday, Moon is in W with Procyon 14 deg below, and the Gemini Twins, Pollux and Castor, to Moon's right. Friday, December 27 If you look at just the right time, from a vantage point with unobstructed views toward east and west, you can see the Summer and Winter Triangles simultaneously. As evening sky darkens, look for bright Vega in NW with Deneb 24 degrees to its upper left. Altair, the southernmost star of the Summer Triangle, is in W, 34 deg to Vega's lower left. As Altair gets low, about 2 hours after sunset from southern U.S., 3 hours after sunset from northern U.S., find Orion in ESE. Reddish Betelgeuse, the Hunter's shoulder, marks the top of the Winter Triangle. Follow Orion's belt downward toward the horizon where Sirius is about to rise. Procyon, in the east to lower left of Betelgeuse, completes the nearly equilateral Winter Triangle. Saturday, December 28 An hour before sunup on Sunday, the waning gibbous Moon is in WSW with Regulus, heart of Leo, 4 degrees above. Bright Mars is in SSW, 30 deg to Moon's upper left. Sunday, December 29 An hour before sunup on Monday, Moon is in SW. Regulus, Leo's brightest star, is 11 deg to Moon's right, and Mars 18 deg to Moon's upper left. Monday, December 30 On Tuesday an hour before sunrise face SSW to find Mars 7 degrees to Moon's upper left. Compare color of Mars to that of Spica, 25 deg to Mars' upper left. Tuesday, December 31 An hour before sunup on New Year's morning, the Moon, just over half full, is in SSW. Find Mars 6 deg to Moon's upper right, and Spica in south, 19 deg to Moon's lower left. Wednesday, January 1, 1997 An hour before sunup on Thursday, face south to find Spica 7 degrees to Moon's lower left. The Moon is just under half full. Mars is in SSW 17 deg to Moon's upper right. Thursday, January 2 In the predawn hours of Friday, the Quadrantid meteors may reach a strong peak. An hour before sunup, face south for Spica 7 degrees to Moon's right. Look very low in SE for bright Venus with Antares, heart of the Scorpion, 13 deg to its upper right. Friday, January 3 From now until late March, Comet Hale-Bopp is a morning object. About 1-1/2 hours before sunrise, locate bright Vega in ENE. Comet H-B is very low in E, 33 degrees lower right of Vega, 20 degrees lower left of the 2nd-mag star Alpha in Ophiuchus, and 9 degrees lower right of the 3rd-mag star Zeta in Aquila. Use binoculars. From one morning to the next, Comet Hale-Bopp now shifts its position against the stars by half a degree per day. Getting a little higher each morning, and possibly brightening through 3rd mag this month, Comet H-B may soon become a naked eye object for billions of viewers in Earth's northern hemisphere. Saturday, January 4 An hour before sunrise on Sunday, look SE for a beautiful crescent Moon with Antares twinking 15 degrees lower left. Bright Venus is 15 degrees lower left of Antares. Sunday, January 5 On Monday an hour before sunrise, the crescent Moon is in SE. Look for Antares, "rival of Mars," 8 degrees to Moon's lower right, and bright Venus 15 deg to Moon's lower left. In three months, on April 2, Venus will be almost directly behind the Sun. Monday, January 6 Last easy chance to view the old Moon! On Tuesday an hour before sunrise, look very low in ESE to SE for the thin crescent with Venus just 4 degrees to its lower right. Tuesday, January 7 Forty to 30 minutes before sunrise on Wednesday, try for the very old Moon rising in ESE. First locate Venus, then, using binoculars, look for faint 1.5-mag Mercury 7 degrees to its lower left. From the East Coast, the hairline-thin crescent is 5 degrees lower left of Mercury and 16 to 17 hours before New. From the West Coast, the more difficult Moon is 7 degrees lower left of Mercury and only 13 to 14 hours before New. Bagging the old Moon is easiest in Southeast U.S., most difficult in the Northwest. When you last spot the Moon, note the time and calculate the time interval remaining until New. The New Moon (its conjunction with Sun) occurs today at 11:26 p.m. EST (8:26 p.m. PST). Will anyone see the "opposing crescents", of Wednesday morning and Thursday evening? Note the times of your last sighting of the morning crescent and first sighting of the evening crescent, instruments used, and send a report to: Moonwatch Jan. '97, c/o Abrams Planetarium, Michigan State University, East Lansing, MI 48824. To prime yourself for these delicate Moons, see the following articles in Sky & Telescope: "Sighting the Opposing Crescents" in May 1995, page 105; and "In Quest of the Youngest Moon" in December 1996, page 104. Wednesday, January 8 On Thursday about 45 minutes before sunup, locate Venus very low in SE sky. Mercury (mag +1.2) is visible in the same 7-power binocular field, 5.5 degrees to Venus' lower left. Mercury is getting higher and brighter each morning, and will pass 4 degrees left of Venus on Jan. 10, and within 3 degrees upper left of Venus on Jan. 12. Thursday, January 9 Within half an hour after sunset, the very young Moon is very low in WSW, and likely to be seen with unaided eye. Its age (time elapsed since New) is less than 18 hours from the Northeast U.S., about 19 hours from Florida, and 21 hours from the West Coast. For the 48 states, this is an easier sighting than the very old Moon of Wednesday morning. This month's young Moon is of special significance to a quarter of the world's population. The first glimpse of the slender crescent marks the beginning of the Islamic holy fasting month of Ramadan. Friday, January 10 Tonight's nearly 2-day-old crescent is very easy to see, low in SW to WSW at dusk. The Moon sets in a dark sky, over two hours after sunset. Very low in SE 45 minutes before sunrise Saturday through Monday, Mercury is 3 degrees upper left of Venus. Within the next few months, a lunar eclipse, Comet Hale-Bopp, and Mars are all slated to put on a fine display in the evening sky. Jupiter, Saturn, and Venus come along later in the year. Beginning tonight, our new show, Celestial Preview 1997, gives tips on how to view these and other phenomena, using Abrams Planetarium's Digistar projector. You'll emerge with an increased enjoyment and appreciation of the ever-changing sky scene. Celestial Preview 1997 is presented two weekends only, January 10-12 and Jan. 17-19, on Fridays and Saturdays at 8 p.m., and Sundays at 4 p.m. Saturday, January 11 On Sunday, very low in SE 45 minutes before sunup, Mercury passes 2.7 degrees upper left of Venus. This is their closest visible pairing with each other until August 1998. Sunday, January 12 Note the large, nearly isosceles triangle formed by Arcturus, Mars, and Spica these mornings. Look for it low in eastern sky 6 hours before sunrise, and high in southern sky one to two hours before sunup. The Big Dipper's curved handle leads directly to Arcturus at the northern apex of the triangle. For the next several weeks, the triangle changles little in shape, with Arcturus about 33 degrees from both Spica and Mars. But watch Mars increase in brilliance, outshining zero-magnitude Arcturus by month's end. Monday, January 13 Locate the waxing crescent Moon well up in SSW at dusk. The first- magnitude "star" a few degrees left of the Moon is Saturn. A telescope reveals the rings, still tipped less than 4 degrees from edgewise. Very low in Tuesday's SE morning sky, three-quarters of an hour before sunup, Mercury stands within 3-1/2 degrees above Venus. ***** end of Skywatcher's Diary for December 1996 *****