****************************************************** Abrams Planetarium SKYWATCHER'S DIARY: February 1998 ****************************************************** The Skywatcher's Diary for February 1998 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 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 February issue, send a long, self-addressed stamped envelope to: February 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 ****************************************************** At dusk at start of February, three planets are visible. Saturn (mag. +0.7) is well up in SW, near crescent Moon on Feb. 1 as depicted on Sky Calendar. Faint Mars (mag. +1.2) and bright Jupiter (mag. -2.0) are very low in WSW, far to Saturn's lower right. Mars and Jupiter are still within 7 degrees apart on Feb. 1, and can be seen together within field of 7-power binoculars. Around end of first week (see Feb. 7) Jupiter sinks into twilight. Mars and Saturn follow Jupiter into the twilight glow, but not until March. Meanwhile, watch the Mars-Saturn gap narrow from nearly 40 degrees on Feb. 1, to 20 degrees on Mar. 1. A young crescent Moon forms pretty groupings with them Feb. 27-Mar. 1. Saturn's rings are tipped 10 degrees from edgewise on Feb. 7, 11 degrees on Mar. 1. Morning: Venus, at mag. -4.6, its brightest this year, now rises in ESE before first light of dawn. Six boxes on Sky Calendar depict Venus an hour before sunrise. To see Venus in daylight, just follow it until sunrise and beyond. The old Moon provides help Feb. 23. Daytime is best for using binoculars or telescope to see Venus' crescent phase. Venus is upper right of rising Sun, by 25 degrees on Feb. 1, 43 degrees on Feb. 28. Crescent Venus on Feb. 1 is 9% lighted and 0.9' (arcminute) across; on Feb. 28 it's 32% lit and 0.6' across. A solar eclipse on Feb. 26, total in a track across the Caribbean, is partial as far north as southernmost CA, lower MI, and Labrador, where the Moon covers at most a few percent of the Sun's disk. From Baton Rouge, Atlanta, Greenville SC, and Richmond VA, Moon covers 25% of Sun's diameter at deepest eclipse, and in Miami FL, 50% of solar diameter. For more on the eclipse, see February Sky and Telescope magazine and visit the websites: http://planets.gsfc.nasa.gov/eclipse/eclipse.html and http://www.skypub.com/eclipses/eclipses.shtml *********SKYWATCHER'S DIARY FEBRUARY 1998********* Sunday, February 1 Forty-five minutes after sunset, the two brightest objects in the sky are the crescent Moon well up in SW, and Jupiter very low in WSW some 47 degrees to Moon's lower right. As the sky darkens further, look for Mars within 7 degrees to Jupiter's upper left, and Saturn a degree or two to Moon's right. A telescope shows spectacular detail on the Moon these nights, as well as the rings of Saturn, tipped nearly 10 degrees from edge-on. Tonight the Sun rises on the crater Theophilus. Through binoculars this feature stands out along the terminator (day-night boundary), about 2/5 of the way from the south cusp (point of the crescent) toward the north. Theophilus is about 65 miles across and over 4 miles deep, with a large multiple central "mountain" easily seen in binoculars. Beginning at sunset, carefully watch Theophilus for 5 hours, and hour by hour you'll notice sunlight illuminating progressively more of the crater's floor and its central mountain. Look again on Monday evening. For a day-by-day description of lunar surface features through the course of a lunar month, see the book, "Exploring the Moon Through Binoculars and Small Telescope" by Ernest H. Cherrington, Jr. Monday, February 2 Tonight a pair of prominent lunar craters, Aristoteles and Eudoxus, lie near the terminator (day-night boundary) less than one-fourth of the way from the northern cusp (upper point of the crescent) toward the southern. Can you see them in binoculars? An hour after sunset, Saturn is high in SW some 15 degrees to the Moon's lower right. Jupiter is about to set in WSW, 46 degrees lower right of Saturn. Faint Mars is 7 degrees to Jupiter's upper left. Tuesday, February 3 The Moon is at First Quarter phase high in SSE at sunset, 90 degrees or one-quarter circle east of the setting Sun. Note the Moon is half full, an ideal phase for seeing lunar surface features through binoculars and telescopes. Using binoculars, "star-hop" to the long period variable star Mira: From the Moon, go 7 or 8 degrees lower left to 2.7-mag. Alpha Ceti. Then from Alpha, go 5 degrees lower right to 3.6-mag. Gamma, and then 3 degrees below Gamma to 4.1-mag. Delta Ceti. Finally, go 6 degrees lower right of Delta to Mira. Is Mira still as bright as Delta? At its peak in Feb. 1997, Mira matched Alpha in brightness. Wednesday, February 4 At nightfall, locate the Pleiades star cluster high in south, about 10 degrees above Moon, and the bright star Aldebaran, eye of Taurus, a similar distance to the Moon's east (left). By Thursday evening, the Moon will have leapfrogged a few degrees past Aldebaran. Four weeks from tonight, the Moon will have completed slightly more than one orbit around the Earth and will occult or cover the star for observers in most of eastern half of U.S. The International Occultation Timing Association (IOTA) would like to receive videos of the March 4 occultation of Aldebaran, taken by camcorders to obtain precise timings. For more information, see our March Sky Calendar, the March issue of Sky & Telescope, and the IOTA website at: http://www.sky.net/~robinson/iotandx.htm Thursday, February 5 At intervals of about 584 days, (just over 19 months), Venus passes nearly between Earth and Sun and switches from an "evening star" to a "morning star". This last occurred in mid-January 1998 and will next happen in August 1999. For several weeks around those dates, Venus appears to retrograde or move westward against the stars. Venus is just now ending retrograde. On Friday morning look for Venus very low in ESE, and note Antares in SSE 40 degrees to Venus' upper right, and 2nd-mag. Sigma Sagittarii in handle of the Teapot, 12 degrees to Venus' lower right. For several mornings these distances will hold stady, then Venus will pull away from these stars with increasing speed. By late March, Venus will be shifting eastward against the stars by one degree per day. Friday, February 6 An hour after sunset, locate the waxing gibbous Moon high in SE, with Betelgeuse, shoulder of Orion, 11 degrees to its lower right. This weekend the Moon joins Betelgeuse inside the huge Winter Hexagon, comprised, in clockwise order, of the stars Aldebaran, Rigel, Sirius, Procyon, Pollux, Castor, and Capella. Milky Way Legacy opens tonight 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. Showtimes: Fridays and Saturdays at 8 p.m., Sundays at 4 p.m., continuing through July. Saturday, February 7 Forty-five minutes after sunset, bid farewell to Jupiter, for it's about to set in WSW. Mars is still visible 10 degrees to Jupiter's upper left. Binoculars help! If you're too late for Jupiter, then look for Mars 35 degrees to Saturn's lower right. Sunday, February 8 WSKY ... Radio Station of the Stars, continues Sundays 2:30 p.m. at Abrams Planetarium. An hour after sunset, Moon is in the east with Procyon, the "Little Dog" star 12 degrees lower right, and Pollux 11 degrees upper left. Castor is 4-1/2 degrees upper left of Pollux. Sirius, the "Dog Star," the brightest star in the night sky, is 26 degrees from Procyon and can also be found by extending Orion's belt downward. Sirius, Procyon, and Betelgeuse (Orion's shoulder) form the nearly equilateral Winter Triangle. Monday, February 9 An hour after sunset, Moon is in east with Procyon 16 degrees to right and Pollux a similar distance above. Regulus, heart of Leo, has just risen 25 degrees to Moon's lower left. Tuesday, February 10 An hour after sunset, the Moon, approaching Full, is in east with Regulus 12 degrees lower left. Tonight's Full Moon is named the Snow or Hunger Moon by Algonquin Indians. By an hour before sunrise on Wednesday, Moon will be low in west, with Regulus within 8 degrees upper left. Wednesday, February 11 An hour after sunset the rising Moon, just past Full, is closely accompanied by Regulus within 2 degrees to its upper left. Binoculars help pick out the star in the Moon's glare. As the night progresses, Moon and star gradually separate. An hour before sunup on Thursday, Moon is in west with Regulus about 5 degrees upper right. Thursday, February 12 Two hours after sunset, the Moon is very low, just north of east, with Regulus 13 degrees upper right (or above the Moon from south Florida). Friday, February 13 At dark sites Feb. 13-27, the zodiacal light appears as a huge, nearly vertical cone of dim light in W at nightfall. How far from the Sun can you detect its glow? Mars, just above the WSW horizon, is 20 degrees from the Sun, and Saturn is now 51 degrees from the Sun. From a fantastically dark site, you may be able to trace the zodiacal light even past the Pleiades or Seven Sisters star cluster, now 95 degrees from the Sun. For more on this phenomenon, see http://antwrp.gsfc.nasa.gov/apod/ap970826.html Saturday, February 14 At nightfall in mid-February, the Milky Way passes nearly overhead. Follow its course from Cygnus low in NW, upward through Cepheus and Cassiopeia, through Perseus and Auriga nearly overhead, then down past the horns of Taurus and feet of Gemini and through the Winter Triangle in the SE. The Milky Way of winter is more subtle and less bright than its summer counterpart, because as we look up toward the horns of Taurus, we are facing away from the bright center of our Galaxy. If you have trouble seeing the zodiacal light or the Milky Way despite clear skies, your problem may be light pollution. For information, see the webpage of the International Dark-Sky Association at: http://www.darksky.org/~ida/index.html Sunday, February 15 An hour after sunset, face WSW to find Mars 30 degrees lower right of Saturn. They'll be 2 degrees apart by end of March, but will set in bright twilight. About 5 hours after sunset, watch for the appearance of Spica in ESE, about 6 degrees to lower right of the waning gibbous Moon. Spica and Moon keep close company for the rest of the night; an hour before sunrise on Monday they're in SW, with Spica about 5 degrees below the Moon. Monday, February 16 Within 5-1/2 hours after sunset, Moon rises 10 to 15 degrees south of east. Note Spica about 10 degrees to Moon's upper right. You can also locate Spica by following the curve of the Big Dipper's handle: "Follow the arc to Arcturus and drive a spike to Spica." By an hour before sunup on Tuesday, face SW to find Spica 12 degrees to Moon's lower right. Tuesday, February 17 An hour after sunset, the bright "markers" in the zodiac constellations (in the plane of the solar system), from western horizon, through high in south, to the eastern horizon, are Mars, Saturn, Aldebaran in Taurus, Pollux in Gemini, and Regulus in Leo. An hour before sunup on Wednesday, the bright zodiac markers, from west to east, are Regulus, Spica in Virgo, the Moon, Antares in Scorpius, and Venus. Around this date each year, the star Regulus in Leo the Lion is at opposition to the Sun as the Earth passes between it and the Sun. Look for Regulus low in eastern sky at dusk, high in south in the middle of the night, and low in W at dawn. During August, half a year from now, Earth will have travelled halfway around the Sun, and Regulus will be lost in the solar glare. Wednesday, February 18 An hour before sunup on Thursday, the Moon is in S, with Antares, heart of the Scorpion, 14 degrees lower left. Moon reaches Last Quarter phase that morning, 90 degrees or one-quarter circle west of Sun. At sunrise, note the Moon's left half is illuminated. Thursday, February 19 An hour before sunrise on Friday, a fat crescent Moon is in SSE to S, with Antares, heart of Scorpius, 9 degrees lower right. Venus, gleaming in SE, is at greatest brilliancy and now shows a crescent, 25 percent full, through binoculars and small telescopes. Just after sunrise, spot Venus in the daytime 40 degrees from Sun and Moon, just above the midpoint between them. Venus passes due south 2 hours 42 minutes earlier and 5 degrees lower than Friday's midday Sun does. (Midday is halfway between sunrise and sunset.) Friday, February 20 Modeling planet visibility: Mercury will appear on the far side of the Sun on Sunday, and Jupiter will do so just a day later. Imagine our solar system from above, and visualize four bodies currently arranged in a straight line, in this order: Earth, Sun, Mercury, Jupiter. As weeks pass, the planets orbit counterclockwise around the Sun at different rates, the inner planets revolving faster. So as seen from Earth, speedy Mercury will emerge to the left of the Sun, while leisurely Jupiter will emerge to the right of the Sun. Meanwhile the Earth rotates counterclockwise on its axis, causing day and night and the daily rising and setting of Sun, Moon, planets, and stars. Recruit volunteers to represent the Sun and planets, and use this solar system model to explain that after appearing behind the Sun, an inner planet (Mercury in this case) will next be visible in the evening sky after sunset, while an outer planet (Jupiter) will next be seen in the morning sky before sunrise. During March, in fact, Mercury will emerge as an evening "star" by the end of the first week, and Jupiter will emerge as a morning "star" before month's end. Saturday, February 21 An hour after sunset, locate Saturn nearly 30 degrees up in WSW, and look for Mars nearly 26 degrees to its lower right. These are planets outside the Earth's orbit and consequently they orbit the Sun more slowly than Earth does. Both planets appear lower in the western sky each evening, and will sink into bright twilight by the end of March. Saturn will be in conjunction beyond the Sun on April 13, and Mars on May 12. Both planets will emerge into the eastern morning sky, Saturn in May, and Mars in July. An hour before sunrise on Sunday, the crescent Moon is in SE with brilliant Venus within 16 degrees lower left. Follow them until well past sunrise. Sunday, February 22 In predawn on Monday, a beautiful pairing of Moon and Venus -- the two brightest nighttime objects -- rewards early risers. Circumstances vary with location. From Lansing, Michigan, Venus rises 4 degrees to Moon's left at 5:03 a.m. EST, just as Moon's crescent becomes fully visible, 2 hours 20 minutes before sunrise. From most locations in U.S. the views of Moon and Venus should be especially striking from two hours to one hour before sunrise. Venus is near greatest brilliancy and is nearly at its highest in the sky for this morning apparition, so this will be one of the most impressive of the monthly pairings of the Moon and Venus. (April 23 will be even more so, including Jupiter only about half a degree from Venus.) Follow Monday's pairing well into daytime, even past midday! From mid-Michigan, Moon-Venus appear closest, 2 degrees apart, just after 1:30 p.m. EST. Monday, February 23 An hour before sunrise on Tuesday, the thin old crescent Moon is very low in ESE, with brilliant Venus 11 degrees to upper right. Tuesday, February 24 Thirty minutes before sunrise on Wednesday, binoculars give the best view of the old crescent Moon, just risen in ESE, 25 degrees to lower left of Venus. This is your last chance to see an illuminated crescent Moon until early Friday evening! Wednesday, February 25 Thursday's solar eclipse, total in a track across the Caribbean, is partial as far north as southernmost CA, lower MI, and Labrador, where the Moon covers at most a few percent of the Sun's disk. From Baton Rouge, Atlanta, Greenville SC, and Richmond VA, Moon covers 25% of Sun's diameter at deepest eclipse, and in Miami FL, 50% of solar diameter. From Michigan, the Moon takes a very small "bite" out of the Sun, as follows: City Time of Deepest Eclipse Magnitude of eclipse Grand Rapids 1:00 P.M. EST 5 percent East Lansing 1:02 p.m. 6 percent Ann Arbor 1:03 p.m. 8 percent Flint 1:03 p.m. 7 percent Detroit 1:04 p.m. 9 percent The magnitude of the eclipse is the fraction of the Sun's diameter covered at the peak of the eclipse. View the eclipse safely! Do NOT attempt to view any stage of the eclipse with the naked eye. One safe method of observing the eclipse is to make a small pencil-point hole in an index card and, standing with your back to the Sun, allow sunlight to shine through the hole to form a projected image on a second white card, held 2-4 feet away. To improve image sharpness, use a smaller hole and employ a long cardboard box to mount the pinhole card at one end and screen (white paper) on the inside at the other end. In East Lansing, begin safe viewing of the eclipse at 12:33 p.m. EST, as the Moon begins to take a "bite" out of the Sun's disk. Deepest eclipse occurs there at 1:02 p.m., and the moon completely uncovers the Sun's disk at 1:30 p.m. For more on the eclipse, including other safe methods of observing it and times for various locations, see February issue of Sky and Telescope magazine and visit the websites: http://planets.gsfc.nasa.gov/eclipse/eclipse.html and http://www.skypub.com/eclipses/eclipses.shtml Thursday, February 26 It's not too early to begin planning for the solar eclipse of August 11, 1999. The centerline of the path of totality of next year's event crosses southwestern England, northern France, southern Germany, Austria, Hungary, Romania, Bulgaria, the Black Sea, Turkey, Iraq, Iran, Pakistan, and India. That will be the last total solar eclipse conveniently accessible to North Americans until the year 2017, when the path of total eclipse will cross the United States from Oregon to South Carolina. Friday, February 27 About 45 minutes after sunset, look for the first young crescent Moon very low, about 10 degrees south of due west. In Michigan, some 30 hours have passed since Thursday's eclipse. Faint Mars is less than a degree to Moon's right. Binoculars give a fine view of the thin crescent with Mars. Saturn hovers 22 degrees to their upper left. Look nightly. Saturday, February 28 Forty-five minutes to an hour after sunset, look between WSW and W for the crescent Moon, with Saturn within 7 degrees above. Mars is about 14 degrees to Moon's lower right. By Sunday evening, Moon will climb to Saturn's upper left. ***** end of Skywatcher's Diary for February 1998 *****