****************************************************** Abrams Planetarium SKYWATCHER'S DIARY Sept 1996 ****************************************************** The Skywatcher's Diary for September 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 Sky Calendar for this month is available over the Internet. It can be viewed via a World-Wide Web browser such at 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: September 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 ******* Celestial Highlights for September ******* September and early October offer a visual feast of celestial phenomena. Bright Jupiter is in south at dusk in September. Saturn in late September rises at sunset and is up all night. Telescopes show Saturn's rings tipped just over 4 degrees from edge-on with their south face in view. Comet Hale-Bopp, visible in binoculars at nightfall and detectable with unaided eye from very dark sites, is on track to become next year's Great Comet. Venus in early September and Mercury in early October reach their highest positions in the morning sky for this year. Venus and Mars appear within 3 degrees of each other in September's first week, and spread to 13 degrees apart by month's end. September's Harvest Moon undergoes total eclipse in close company with Saturn; totality can be witnessed in all North America except western Alaska. The end of September and early October bring us four naked-eye planets (all except Jupiter) simultaneously visible in morning twilight. A daily morning skywatch will be especially rewarding October 1-11, giving a view of Venus passing Regulus Oct. 1-6 (they're closest on Oct. 3 and 4), and the waning crescent Moon sliding down past Mars, Regulus, Venus, and Mercury October 7-11. For the total lunar eclipse on Sept. 26, most North Americans have ringside seats! What colors do you see on Moon during totality? Refer to the article on pp. 68-71 in September Sky & Telescope for some observing projects, or check their eclipses site at: http://www.skypub.com/eclipses/eclipses.html Look for Saturn glowing strikingly just 2 degrees from the shadowed Moon. Listen for the sounds of insects --which you can hear on most any night this time of year, not just during a lunar eclipse. During a total lunar eclipse in Aug 1989 we heard Katydids. Hawthorne called the rhythmic chirping of Snowy Tree Crickets "an audible stillness" and added that "if moonlight could be heard, it would sound like that." -- Crickets and Katydids, Concerts and Solos, by Vincent D. Dethier. West of longitude 114 degrees to Coast, Moon rises with eclipse already underway; will anyone there see Sun in west and partially eclipsed Moon in east, simultaneously? Total lunar eclipses can often be remembered by some unique or unusual feature. In December 1963, the eclipsed Moon was so dark and faint that it could be glimpsed only by knowing where to look, using averted vision. The presence of aerosols in our stratosphere, resulting from a major volcanic eruption in Indonesia, had blocked most of the sunlight from getting through our atmosphere to the Moon. Unusually dark eclipses in 1982, 1992, and 1993 followed major eruptions in Mexico and the Phillipines. In April 1968, our planetarium staff, observing from a dark rural area, saw a beautifully colored eclipsed Moon in close conjunction with Spica. The edge of the Moon nearest to Spica was bluish in color, as if the star were illuminating the Moon. The opposite limb of the Moon, deepest within Earth's shadow, was a dark chocolate-brown, and the rest of the Moon was red-orange. We'll always remember August 16, 1989 as the date of the "Katydid total eclipse", because as we watched the event from outside MSU Observatory, these insects of late summer and early fall were scraping their raucous "love songs" from the treetops. The total lunar eclipse on Thursday, September 26 may combine some aspects of those of 1968 and 1989, because this year's event also has a bright companion "star", Saturn, only 2 degrees away. The off-center location of the Moon within Earth's shadow usually produces good gradients of darkness and color, especially at start and end of totality. But at mid-totality, 10:54 p.m. EDT, the Moon will be closer to the shadow center than in 1968, so this eclipse may be darker and less colorful than the one in 1968. This time, the Moon's brighter edge will be the northern limb, the side away from Saturn. For our September Sky Calendar, which includes an illustration depicting the various stages of this eclipse and an evening sky map, point your Web Browser to: http://www.pa.msu.edu/abrams/skycal.html This month's eclipse, as in 1989, occurs during the season for Katydids, provided we haven't had a hard frost by Sept. 26. We also expect to hear the rhythmic chirping of Snowy Tree Crickets. We've been hearing these two species since mid-August (both started later than usual, perhaps because of a cold spring); for a checklist of Michigan Orthoptera, set your Web browser to: http://insects.ummz.lsa.umich.edu/fauna/Michorthops.html Locating Comet Hale-Bopp in September: Using our all-sky map, September Evening Skies, locate the 2.1-mag star Rasalhague, or Alpha in Ophiuchus, 2/5 of the way from Vega to Antares. It's also 2/5 of the way from Altair to Arcturus, but a little south of a line connecting them. Alpha Oph, marking head of Ophiuchus, the Serpent-bearer, stands out as the brightest star within the giant quadrilateral Vega-Altair-Antares- Arcturus. Next, find 2.8-mag Beta 8 degrees lower left of Alpha, and 2.4-mag Eta Oph 14 degrees upper left or above Antares and 22 degrees below Beta Oph. The 4.5-mag star SAO141665 is nearly halfway from 2.8-mag Beta Oph toward 2.4-mag Eta Oph, and 11 degrees from each. At nightfall on Sept 1, Comet Hale-Bopp is easily seen in binoculars 3.2 degrees left of SAO141665 and 1.6 degrees upper right of Mu Oph. On Sept 15, Comet H-B is 1.4 degrees left of SAO141665 as shown on map. During Sept 25-Oct 2, comet lingers about 0.8 degree from SAO141665, and passes due east (upper left) of it Sept 29. Prospects for Comet Hale-Bopp: Comet expert and Michigan State University Alumnus Charles S. Morris at NASA's Jet Propulsion Laboratory has issued a brightness forecast for Comet Hale-Bopp from now until its closest approach to Earth and Sun in late March next year, and it is good news! Since Earth is temporarily receding from Comet Hale-Bopp until late October, the comet brightens slowly for now, to mag. 5 in September and to mag. 4 sometime in November. At the turn of the year, as the comet sinks into the western twilight glow and emerges into the eastern morning sky, Morris predicts it will glow between 3rd and 2nd magnitude. If the comet is bright enough, observers at mid-northern latitudes may be able to follow it without interruption as it passes 28 degrees N of Sun on December 30. Comet Hale-Bopp in 1997: From January well into March, Comet Hale- Bopp is expected to brighten in E to NE predawn sky as it closes in on both Earth and Sun. On March 21 it once again passes solar conjunction, this time 45 degrees to the Sun's north. For several days, comet will appear both in NE at dawn's first light and in NW at nightfall. A few days later, on a moonless evening in late March, Hale- Bopp is expected to peak in brightness, between mag. -0.5 and -2.0, according to Morris. But he cautions, quoting from his very good friend, comet discoverer-observer, and writer David Levy: "Regarding people who insist that [Hale-Bopp will be very bright in 1997]: Comets are like cats. They have tails, and they do precisely what they want." For more on Hale-Bopp: http://encke.jpl.nasa.gov/hale_bopp_info.html Also check Sky & Telescope's site: http://www.skypub.com/ ********* SKYWATCHER'S DIARY: SEPTEMBER 1996 ********* Sunday, September 1 Beginning tonight, you have a respectable interval of dark skies for viewing the Milky Way and Comet Hale-Bopp. Tonight's dark window ends with Moon's rising over 2-1/4 hours after sundown for skywatchers in lower Michigan, and later for viewers farther south. At nightfall, locate Jupiter in S and Antares in SSW, 28 degrees lower right of Jupiter. Look for 2.4-mag Eta Ophiuch 14 degrees upper left of Antares, and Comet H-B another 11 degrees upper left of Eta. All three bodies appear in a straight line. A 4.6-mag star, Mu Ophiuchi, lies 1.6 degrees lower left of the comet. Once you find the comet, it's easy to track this month, since it shifts position against ths stars by less than 3 degrees during Sept. 1-30. In the eastern morning sky for over three hours before sunrise, Venus and Mars are just 3 degrees apart all this week; they appear closest at midweek, as Venus passes within 2.9 degrees south of Mars. Monday, September 2 Jupiter, in the south as darkness falls, ends retrograde this week. Note the 3rd-magnitude star Lambda Sagittarii, northern star of the Archer's bow and top of the Teapot, just 2-1/2 degrees lower right of Jupiter. A telescope shows a ball of stars 0.7 degree from Jupiter. In coming weeks, even as Jupiter and the Teapot drift toward the southwest horizon, watch the planet slowly move eastward against the stars, increasing its distance from Lambda. Tuesday, September 3 Withiin 4 hours after sunset, the Moon rises in ENE. Within half an hour later, look for Aldebaran about 4 degrees to Moon's lower left. Watch the Moon creep ever closer to this star for the rest of the night. An hour before sunup on Wednesday, Moon and star are high in SSE, while Venus gleams in east accompanied by faint Mars within 3 degrees upper left. Wednesday, September 4 An hour before sunup on Thursday, the fat crescent Moon is high in SE with Aldebaran, eye of Taurus the Bull, 11 degrees to its upper right. Thursday, September 5 An hour before sunup on Friday, the waning crescent Moon is in ESE. Betelgeuse, Orion's bright shoulder, and Rigel, the Hunter's foot, are respectively 11 and 30 degrees to Moon's lower right. Midway between these colorful stars lie the three stars of Orion's belt. Friday, September 6 An hour before sunup on Saturday, begin with the crescent Moon in E to ESE. Venus, the brilliant morning "star", is 16 degrees to Moon's lower left. Mars is still just 3 degrees to Venus' upper left. Above the planet duo lie the Gemini Twins, Castor 4-1/2 degrees above Pollux. Procyon, the Little Dog Star, lies 15 degrees lower right of Moon and Venus. Saturday, September 7 An hour before sunup on Sunday, don't miss the beautiful gathering in the east: A slender crescent Moon with brilliant Venus and faint Mars within 7 degrees to its left. The star Procyon lies 11 degrees to Moon's lower right. Another 26 degrees lower right of Procyon look for blazing blue-white Sirius, the Dog Star, brightest nighttime star (but not as bright as Venus). Note Orion's 3-star belt points downward toward Sirius. Betelgeuse (Orion's bright shoulder), Procyon, and Sirius form the nearly equilateral Winter Triangle. Sunday, September 8 An hour before sunup on Monday, face east and find brilliant Venus 7 degrees above the Moon. Still higher, note the nearly straight alignment of Venus-Mars-Pollux-Castor, and watch for changes in the coming week. Can you spot Regulus Monday morning, very low, 22 degrees to Moon's lower left? Monday, September 9 On Tuesday an hour before sunup, look for the old crescent Moon low in east, 17 degrees lower left of brilliant Venus. Notice the beautiful earthshine on the Moon's dark side. The star Regulus, heart of Leo, is visible, 10 degrees to Moon's lower left. Tuesday, September 10 Last chance to see the old crescent Moon! On Wednesday an hour before sunup, it's barely above the horizon 8 degrees north of due east. Find Venus 30 degrees up in east, Mars 4 degrees to Venus' upper left, Regulus 25 degrees to Venus' lower left, and finally the very thin Moon within 5 degrees lower right of Regulus. Binoculars help locate the delicate crescent in bright twilight, 37 hours before New for Michigan skywatchers. Wednesday, September 11 The brightest objects in the current evening sky an hour after sunset are: Steady yellow-white Jupiter in south; golden Arcturus in the west, one- third of the way from horizon to overhead; and blue-white Vega overhead. Thursday, September 12 The Moon is New this evening at 7:07 p.m. EDT (4:07 p.m. PDT), and is not visible. Friday, September 13 On Friday evening, no casual sightings of the young crescent Moon are likely within the U.S. except possibly Hawaii, where the Moon will be very low, just S of due west 20 minutes after sunset. Saturday, September 14 About 20 minutes after sunset, look for the young Moon very low, 10- 15 degrees S of due west. Note the crescent "pours water out", like a bowl tipped nearly on its side. Although the Moon sets early, barely 3/4 hour after sundown for viewers at the latitude of Boston and East Lansing, MI, it nonetheless is easy for punctual viewers with clear skies and an unobstructed horizon. That's because the crescent, some 23 degrees from the Sun, is rather bright, 4 percent illuminated. As the Moon sinks toward the horizon, binoculars may show Spica 8 or 9 degrees to its upper left. Sunday, September 15 Hald an hour after sunset, the Moon is easy to see very low in WSW. In the next quarter-hour, use binoculars to try for Spica 5 degrees to Moon's lower right. Viewers in southern states can spot it more easily. In mid-October, Spica will appear on the far side of the Sun. Monday, September 16 This is the first evening that the Moon sets after nightfall. Look for the crescent very low in WSW an hour after sunset. The bright star in west 33 degrees to Moon's upper right is Arcturus. Jupiter is even brighter in the south. Can you spot Antares about midway between Moon and Jupiter? Look a few degrees below the line connecting them. Tuesday, September 17 Only nine days to go before the total lunar eclipse! See September 21, 25, and 26, below. Wednesday, September 18 A crescent Moon, one-third full, is in SW at nightfall, about 1-1/2 hours after sunset. Find Jupiter in S to SSW, 30 degrees left of Moon, and the first-magnitude star Antares, heart of Scorpius, 8 degrees to Moon's lower left. About 10 degrees to Moon's upper left is the 2.4-mag star Eta in Ophiuchus; 11 deg above Eta and 24 deg upper right of Jupiter lies Comet Hale-Bopp! Binoculars give an easier view of this 5th- magnitude hazy patch. Thursday, September 19 Tonight at nightfall, find the Moon in SSW to SW, with Jupiter 17 degrees to its left. Binoculars may show Comet Hale-Bopp 13 degrees to Moon's upper right. Although the Moon will move away from the comet in coming nights, the Moon's increase in phase will brighten the sky and make the comet harder to observe. Friday, September 20 The two brightest evening objects, Moon and Jupiter, form an eye- catching duo within 5 degrees apart in the southern sky at dusk. On Saturday, 1-1/2 hours before sunrise, find brilliant Venus in the east. Look for Regulus 14 deg to Venus' lower left, and Mars 8 or 9 deg to Venus' upper right. (Mars is almost directly above Venus from southernmost U.S.) Binoculars show stars of the Beehive cluster appearing to surround Mars. The stars of the cluster are actually about 500 light-years distant, while light from Mars reaches Earth in less than 17 minutes. So the Beehive stars are some 16 million times as far away as Mars! Saturday, September 21 As the Moon passes south tonight, 1 hour 20 minutes after sunset, bright Jupiter is 12 degrees to its lower right. Low in E to ESE, some 75 degrees east of the Moon tonight, lies first-magnitude golden-yellow Saturn, Look nightly until Thursday, when Moon will have a marvelous rendevous with Saturn, splendidly timed to coincide with a total lunar eclipse! Sunday, September 22 Autumn begins at 2:00 p.m. EDT today, as the Sun crosses directly over Earth's equator near the Galapagos Islands west of South America. Each day at this time of year, the latitude of overhead Sun shifts southward by about 27 miles per day. Monday, September 23 From now until the end of October, watch the changing arrangement of two planets and a star in the eastern predawn sky. This Tuesday and Wednesday, Venus is about midway between reddish Mars above and bluish Regulus below, and 10 to 11 degrees from each. Tuesday, September 24 Using binoculars about 45 minutes before sunrise these mornings, scan the horizon nearly due east for Mercury. On Wednesday it's nearly 30 degrees lower left of Venus. Now of magnitude +1.4, Mercury will nearly quadruple its brightness to mag 0 by month's end. Wednesday, September 25 One night to go until lunar eclipse! On Wednesday an hour after sunset, the Moon is in ESE with Saturn 16 degrees lower left. On Thursday evening the Sun, Earth, Moon, and Saturn will lie in a straight line. The result: A spectacular lunar eclipse in close company with Saturn. Here's some information about Thursday evening's total lunar eclipse: Total Eclipse of the Harvest Moon, September 26, 1996 Last April 3, a total eclipse of the Moon was well seen only from eastern U.S. This Thursday, a greater portion of the country will be in good position to view the year's second total lunar eclipse. A striking feature will be the presence of Saturn only about 2 degrees from the eclipsed Moon. Not since April 12, 1968 have North Americans seen the totally eclipsed Moon so close to a bright object (it was Spica), and not again until February 20, 2008 will the Moon in total eclipse again appear within a few degrees of a bright object, actually two objects, Saturn and Regulus! The umbra, or dark central core of Earth's shadow, as projected on the Moon during lunar eclipse is usually a deep reddish orange or rusty color, from sunlight which passes close to Earth and is bent, by our atmosphere, into the shadow. The color isn't usually noticed until most of the Moon is covered by the umbra. (more) The entire umbral eclipse, including totality, will be above the horizon for all of the U.S. east of longitude 114 degrees W (northwestern Montana through east boundary of Nevada and western Arizona). West of those locations to the West Coast, the Moon will rise with the umbral eclipse already in progress. Near longitude 114 degrees W and a little farther west, from places with good horizon views, it may be possible to observe Sun and partially eclipsed Moon simultaneously, a few minutes after the Moon begins to enter the umbra. (If you make such a sighting, please send us a report!) From Hawaii and western Alaska, the Moon rises during the closing partial phases, after totality is over. From the U.S. West Coast and possibly as far east as Salt Lake City, the Moon may disappear in twilight as the eclipse becomes total, and reappear, still in total eclipse, as the sky darkens. LUNAR ECLIPSE ON NIGHT OF SEPTEMBER 26-27 Moon enters umbra 9:12 p.m. EDT * * = not visible Total eclipse begins 10:19 p.m. EDT 7:19 P.M. PDT Deepest eclipse 10:54 p.m. EDT 7:54 P.M. PDT Total eclipse ends 11:29 p.m. EDT 8:29 P.M. PDT Moon leaves umbra 12:36 a.m. EDT 9:36 P.M. PDT A deep, possibly very colorful partial eclipse, 92% in shadow, will be visible in all U.S. except Hawaii and Alaska, on the night of March 23, 1997. The next total lunar eclipse for us will be visible throughout the Americas and Hawaii on January 20, 2000. Thursday, September 26 Enjoy the eclipse! During the event, notice the alignment of the east side of the Great Square of Pegasus (Alpha Andromedae and Gamma Pegasi) with the Moon, Saturn, and Iota Ceti. Our map, September Evening Skies, represents the sky about 1-3/4 hours after sunset during eclipse night, and an illustration depicting the various stages of the eclipse appears on our September Sky Calendar. Both are available on the World Wide Web at: http://www.pa.msu.edu/abrams/skycal.html Friday, September 27 From northern U.S., the Moon rises about 8 degrees north of east within half an hour after sunset. As the sky darkens, note Saturn 13 degrees to Moon's upper right. Saturday, September 28 Tonight from the latitude of Boston and East Lansing, MI, the Moon rises just over an hour after sunset. Find Saturn 28 degrees to Moon's upper right. A telescope shows the rings tipped just over 4 degrees from edge-on. Sunday, September 29 Now that the Moon rises late enough to allow a brief "window" of dark evening skies, this is a good date to resume following Comet Hale- Bopp. Using our Sky Calendar and Evening Skies map, look in Ophiuchus, halfway between the stars Beta and Eta, 11 degrees from each star. There you'll see a fuzzy patch (the comet), within 0.8 degree from a 4.5-mag. star. From now until mid-October, the comet changes position against the star background by barely a degree, and moonlight doesn't interfere. About an hour before sunrise for the next week, four planets are visible simultaneously. Begin with Venus in the east. On Monday morning, Mars is 13 degrees upper right of Venus, while Regulus and Mercury are respectively 4 deg and 24 deg to Venus' lower left. Turn around to spot Saturn about to set a few degrees south of due west. In sequence from east to west, note the beautiful alignment of Mercury, Regulus, Venus, Mars, Pollux, Aledbaran, Moon, and Saturn. All appear within the celestial beltway known as the zodiac, which appears nearly vertical in the predawn sky in late summer and early fall. Monday, September 30 Tonight from northern U.S., the Moon rises in ENE about 2-1/2 hours after sunset. Another hour later, look for Aldebaran 10 degrees to Moon's lower left. Watch the Moon creep a few degrees closer to Aldebaran overnight. By an hour before sunup on Tuesday, they're high in SW. ********* end of Skywatcher's Diary for September, 1996 *********