****************************************************** Abrams Planetarium SKYWATCHER'S DIARY: August 1998 ****************************************************** The Skywatcher's Diary for August 1998 has been prepared by Robert C. Victor. Credit to the author and to Abrams Planetarium, Department of Physics and Astronomy at Michigan State University, and mention of our Sky Calendar, would be appreciated. A sample recent issue of Sky Calendar is available over the Internet. It can be viewed via a World-Wide Web browser such as Netscape or Internet Explorer, directly at URL: http://www.pa.msu.edu/abrams/apr97skycal.html If you would like a printed sample of the August issue, send a long, self-addressed stamped envelope to: August 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 Internet Explorer, 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 ****************************************************** Giants rise in evening! Jupiter, gleaming with rare brilliance, rises just south of due east, two hours after sunset in a dark sky on Aug. 1, and 40 minutes after sunset (around middle of evening twilight) on Aug. 31. Saturn rises late in evening, about 1-1/2 to 1-3/4 hours after Jupiter does. Watch for a bright "star" rising north of east, far lower left of Jupiter. For rest of the night, Saturn trails Jupiter across the sky, 36 to 38 degrees E of the giant planet and three magnitudes fainter. Diary entries for the nights of Aug. 9-13 decribe the arrangement of Moon, Jupiter and Saturn at various times of the night. Jupiter at dawn is well up in SSW at start of August and drifts lower into WSW as month progresses. Saturn is very high at dawn, crossing from SE through S toward SW during month, nicely placed for telescopic viewing. Saturn's rings are tipped nearly 17 degrees from edge-on, our best view this year. Other planets at dawn: Brilliant Venus on Aug. 1 rises nearly 2 hours before sunrise, or just before first light of dawn. Faint Mars appears very close by in first week, passing within 0.9 degree on Aug. 4 & 5, and ends month 15 degrees upper right of Venus. Watch for straight lineup of Venus-Pollux-Castor on Aug. 11 & 12; and of Mars-Pollux- Castor on Aug. 17 & 18. Moon passes near Venus and Mars on Aug. 19 & 20. By Aug. 23, Mercury (mag. +1.7) can be spotted within 5 degrees lower right of Venus. Use binoculars. Mercury brightens rapidly in next week, to mag. +1 by Aug. 26 and mag. 0.0 by Aug. 30. Once Mercury is easily seen at dawn in the last days of August, all five naked-eye planets can be simultaneously viewed in morning twilight. The best time to look may be about one hour before sunrise. On Aug. 27 & 28 Mercury passes 2.3 degrees S (right) of Venus. Mercury appears highest on Sept. 1, as it widens to a maximum distance of 2.9 degrees upper right of Venus. Mercury will brighten further in early September and form a very compact grouping with Venus and Regulus, an impressive sight for binoculars. Details will appear in our Sky Calendar and Skywatcher's Diary for September. Skywatcher's Diary: August 1998 Saturday, August 1 Milky Way Legacy concludes this weekend at Abrams Planetarium. Tour our amazing home galaxy with noted author Ken Croswell and emerge with a clearer view of our home in space. Find out some of the ways the Milky Way is very special, and how, unlike most galaxies, it is equipped to create the variety of ingredients needed for life. Final showings are Fri. July 31 and Sat. Aug. 1 at 8 p.m., and Sunday Aug. 2 at 4 p.m. Also this Friday and Saturday, July 31 and August 1, MSU Observatory will be open for public viewing from 9:00 until 11:00 p.m. if skies are clear. The Moon, two-thirds full, is in SSW an hour after sunset, with Antares, heart of Scorpius, about 15 degrees to its lower right. Between Moon and Antares lies a nearly vertical line of three stars, the Scorpion's head. An hour before sunrise on Sunday, brilliant Venus is very low in ENE, with faint Mars 1.7 degrees lower left. Watch for changes in next few mornings. Look also for Pollux and Castor, the Gemini twins, 9 to 11 degrees to Venus' left, and Orion in E to ESE. Sunday, August 2 The final presentation of our family show, WSKY ... Radio Station of the Stars, is today, 2:30 p.m. at Abrams Planetarium. The Moon, three-quarters full, passes south soon after sunset. As sky darkens, look for Antares, heart of Scorpius, 9 degrees below the Moon. An hour before sunup Monday, Venus is very low in ENE; Mars is 1.2 degrees lower left. Monday, August 3 An hour after sunset, the Moon is in the southern sky, with Antares 15 degrees lower right. An hour before sunrise on Tuesday and Wednesday, brilliant Venus and faint Mars, very low in ENE, are at their closest, 0.9 degree apart. Mars is to Venus' north (left or upper left). Two other naked-eye planets: Bright Jupiter well up in SSW, and Saturn high in SE. Tuesday, August 4 The Teapot of Sagittarius is in the south two hours after sunset, but the Moon's presence just 6 degrees above the top of the lid will prevent observation of the Sagittarius Milky Way. Wait until at least Aug. 11, when the Moon won't be up yet at that hour. Wednesday, August 5 An hour before sunup on Thursday, brilliant Venus is very low in ENE with faint Mars within 1.2 degrees above. Pollux is within 7 degrees upper left of the pair, and Castor 4-1/2 degrees above Pollux. Watch the changing configuration of these four bodies in coming days. Venus- Mars will still be only 2 degrees apart on Saturday. Thursday, August 6 Half an hour before sunset, Sun and Moon are simultaneously visible, low in sky in nearly opposite directions. An hour before sunrise on Friday, look low in ENE for brilliant Venus with faint Mars 1.6 degrees above. Friday, August 7 A few minutes before sunset, as the Sun rests on WNW horizon, look in the exact opposite direction to see the Full Moon, just risen. You'll need unobstructed views toward WNW and ESE to see both Sun and Moon simultaneously. August's Full Moon was known to Algonquin Indians and colonial Americans as the Green Corn Moon. Tonight the Moon is up all night, setting about half an hour after sunrise on Saturday. Saturday, August 8 About half an hour after sunset from northern U.S. (a little later from southern U.S.), look for Moon just risen 15 to 20 degrees S of due east. Note the Moon's reddish color when it's rising, caused by the scattering out of the bluer light by Earth's atmosphere. Next week, as seen from the latitude of Massachusetts, through lower Michigan, to southern Oregon, the Moon rises some 35 to 40 minutes later and about 6 degrees farther north nightly. For southern U.S. the nightly delay of moonrise time is a few minutes longer. Sunday, August 9 Two hours after sunset, the waning gibbous Moon is low in ESE, with bright Jupiter trailing within 13 degrees to its lower left. An hour before sunup on Monday, they're high in SSW to SW, with Jupiter some 9 degrees to Moon's upper left. Also in the morning, look for Saturn high in SSE, 36 degrees to Jupiter's upper left, and for brilliant Venus very low in ENE. Faint Mars, 3 degrees to Venus' upper right on Monday morning, is passing within 6 degrees lower right of Pollux, the brighter of the Gemini twins. Castor, the other twin, is 4-1/2 degrees upper left of Pollux. Monday, August 10 Two hours after sunset, the waning gibbous Moon is very low, a few degrees south of due east, with bright Jupiter 2 or 3 degrees to its upper right. By an hour before sunup on Tuesday, Moon and Jupiter will be high in SSW, some 5 or 6 degrees apart. Tuesday, August 11 Tonight the Moon rises just north of east, within 2-1/2 hours after sunset from northern U.S. Wait an additional hour, and you can see two planets flanking the Moon: Bright Jupiter 17 degrees to Moon's upper right, and Saturn 19 degrees to Moon's lower left. By an hour before sunup on Wednesday, the long line of three bodies is high in the southern sky, with the Moon just over halfway from Jupiter toward Saturn. Wednesday, August 12 Tonight the interval from nightfall until moonrise will provide a "window" of very dark skies without twilight or moonlight, excellent for viewing the Perseid meteor shower if you're away from the lights of civilization. Meteors can flash into view anywhere in the sky, but members of the shower, if their paths are extended backward far enough, will streak away from an area in the northeast sky in the constellation Perseus, below the "W" of Cassiopeia. The Moon. two- thirds full, rises within three hours after sunset (from northern U.S.), brightening the sky for the rest of the night, and reducing the number of faint meteors visible. The Moon keeps close company with Saturn for the rest of the night, until dawn on Thursday. Low in ENE at dawn on Thursday, Venus and Mars have spread to 5 degrees apart. Thursday, August 13 Four hours after sunset, the Moon is very low, 10 degrees N of due east and 10 degrees lower left of Saturn. Approaching Last Quarter, the Moon is still slightly over half full. Friday, August 14 One-and-a-half hours before sunup on Saturday, the fat crescent Moon, high in ESE, is nearly half full. Look for the Pleiades star cluster 10 degrees to Moon's upper left, and first-magnitude Aldebaran, eye of Taurus, about as far to Moon's lower left. Binoculars give a fine view of the Pleiades, and also of the V-shaped hyades cluster near Aldebaran. Saturday, August 15 One-and-a-half hours before sunup on Sunday, the Moon is one-third full in E to ESE. Aldebaran, reddish eye of Taurus, is some 4 degrees to Moon's upper right, while stars of the Hyades, forming rest of the Bull's head, lie closely above and upper right of Aldebaran. Sunday, August 16 An hour before sunrise on Monday, between E and ESE, find the waning crescent Moon, with Betelgeuse, shoulder of Orion, 11 degrees to its lower right. Some 10 degrees right of Betelgeuse, look for Orion's belt, a vertical line of three stars less than 3 degrees long. Rigel, Orion's bright foot, is 9 degrees to the right of the belt. Watch for the rising of Sirius, the Dog Star, which can be found by extending Orion's belt downward 22 degrees toward the ESE horizon. Procyon low in the east completes the nearly equilateral "Winter Triangle" with Betelgeuse and Sirius. Monday, August 17 An hour before sunup on Tuesday, the waning crescent Moon is nearly due east, with brilliant Venus low in ENE, 25 degrees to Moon's lower left. Mars is between them, 8 degrees to Venus' upper right. On Tuesday morning the Moon is nearly encircled by five bright objects, each 16 to 18 degrees away: In clockwise order, they are Betelgeuse to Moon's right, Procyon below the Moon, Mars to Moon's lower left, and Pollux and Castor, the Gemini twins, to Moon's left. Tuesday, August 18 On Wednesday an hour before sunup, the thin crescent Moon is low, N of east, with brilliant Venus 13 degrees to its lower left. Faint Mars is 8 degrees upper right of Venus and about 6 degrees to Moon's lower left. Look for Procyon 12 degrees to Moon's lower right, and Pollux and Castor, the Gemini twins, 10 and 15 degrees to Moon's upper left. Wednesday, August 19 Thursday morning will be your last chance to see the old Moon of the current lunar cycle. An hour before sunrise, look very low in ENE for the thin crescent with Venus 3 degrees to its upper left. Faint Mars is within 9 degrees upper right of Venus and a similar distance lower right of Pollux. Thursday, August 20 The Moon will be New on Friday at 10:13 p.m. EDT. An annular (ring) solar eclipse will be seen from some islands in and around Indonesia. After this morning's old crescent, the Moon can next be seen as a young crescent early on Sunday evening. Friday, August 21 On Saturday an hour before sunrise, find brilliant Venus very low in ENE and then locate faint Mars 10 degrees to its upper right and 10 degrees below Pollux. On Saturday morning and early next week, you can also locate Mars by extending a straight line from Sirius (very low in ESE) through Procyon (low in E) to Mars. Saturday, August 22 Each year around this date, the star Regulus, heart of Leo, appears almost directly behind the Sun. In two to three weeks, Regulus emerges into the morning sky, this year appearing very close to Venus and Mercury Sept. 6-8. Stay tuned! Sunday, August 23 About 20 or 30 minutes after sunset, the almost two-day-old crescent Moon is nearly due west, very low. Binoculars give the best view of the thin young crescent. Monday, August 24 For the first few nights of its current cycle, the Moon sets less than half an hour later each evening from northern U.S. Thirty minutes after sunset tonight, the Moon is easy to see, low, south of west. By an hour after sunset, it has nearly set, due west. Look nightly, and you'll notice the Moon is waxing, or growing thicker from night to night, as it moves farther from the Sun in the sky. An hour before sunrise on Tuesday, aim binoculars toward Venus very low in ENE and look for Mercury 3 degrees to its lower right. Mercury will appear higher each morning for another week and brighten, and by this week's end will climb higher than Venus. Tuesday, August 25 An hour after sunset, look low in WSW for first-magnitude Spica 8 degrees lower left of the waxing crescent Moon. This star will disappear into the twilight glow in September. An hour before sunrise on Wednesday, binoculars help locate Mercury just 2.5 degrees lower right of Venus, low in ENE twilight glow. From then until Sept. 15, Mercury will stay within 3 degrees of Venus. Wednesday, August 26 An hour after sunset, crescent Moon is in WSW with Spica 7 degrees below. Jupiter is just rising 5 degrees S of east. An hour before sunup next two mornings, very low in ENE, Mercury appears 2.3 degrees S (right) of Venus. Dim Mars appears 13 degrees upper right of the pair. Two additional planets are visible, bringing the total to all five naked-eye planets visible simultaneously! They are bright Jupiter in SW, and Saturn high in SSW. Thursday, August 27 An hour before sunup on Friday, Venus and Mercury are still 2.3 degrees apart very low in ENE, their closest until they come even closer in September's second week. In the two weeks from now until then, all five naked-eye planets can be viewed simultaneously! Friday, August 28 With the Moon near half full, this weekend is ideal for observing the Moon with binoculars or a small telescope. Look for craters and other lunar surface features, especially near the Moon's terminator (day-night boundary), where long shadows are cast. An hour before sunrise on Saturday, Mercury has climbed higher than Venus, and appears 2.4 degrees to Venus' upper right. Look very low in ENE; binoculars give the best view. Saturday, August 29 An hour after sunset, look in SSW to find Antares, heart of Scorpius, 10 degrees lower left of the half-illuminated Moon. The Scorpion's head is marked by a vertical, slightly curved line of stars 4 to 7 degrees below the Moon, which is at First Quarter phase tonight. An hour before sunup on Sunday, find brilliant Venus very low in ENE, with Mercury 2.6 degrees to its upper right. Mars is now nearly 15 degrees upper right of Venus. Bright Jupiter is in SW to WSW, and Saturn is in SSW, 38 degrees to Jupiter's upper left. Sunday, August 30 This evening the Moon is slightly gibbous (more than falf full), with the red supergiant star Antares in SSW, 11 degrees to its lower right. An hour before sunup on Monday, Mercury reaches greatest elongation, 18 degrees from Sun. Although very low in ENE, it's easy to find, just 2.8 degrees upper right of Venus. Monday, August 31 An hour before sunrise on Tuesday and Wednesday, Mercury reaches a maximum distance of 2.9 degrees upper right of Venus. After Wednesday, the gap between the planets will narrow until Mercury passes just 0.4 degree left of Venus on Sept. 11. Binoculars give the best views of the pair of inner planets. Look low, between ENE and E. ********* end of Skywatcher's Diary for August 1998 *********