****************************************************** Abrams Planetarium SKYWATCHER'S DIARY July 1996 ****************************************************** The Skywatcher's Diary for July 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 May 1996 is available over the Internet. It can be viewed via a World-Wide Web browser such at Netscape or Mosiac, directly at URL: http://www.pa.msu.edu/abrams/may96skycal.html If you would like a printed sample, send a long, self-addressed stamped envelope to: July 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 Mosiac, 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 ******* Lunar and Planetary Highlights for July ******* Jupiter is a bright all-night object on July 4. An hour after sunset, Jupiter is very low in SE, and slowly gains altitude all month, ending in SSE. Comet Hale-Bopp is an easy target for binoculars, with little or no interference from moonlight July 4-22. Venus in July reaches its greatest brilliance as a morning "star." Venus rises in ENE 1-1/2 hours before sunup on July 1, and over 3 hours before sunup on July 31. Venus is 33 to 52 million miles from Earth this month, so its backlighted globe appears an unusually large 0.8' (arcminute) across on July 1, 0.5 arcminute on July 31. Especially in early July, Venus seen through binoculars appears big enough to discern its crescent shape, provided you observe it in a bright sky, around sunrise or even in daylight. An easy way to see Venus in the daytime is to just keep track of it until sunrise! Venus' angular distance to upper right of the rising Sun widens from 28¡ on July 1 to 44¡ on July 31, while the sunlit fraction of Venus' disk grows from 13% to 38%. A Last Quarter Moon leads the eye toward Saturn in SE predawn skies on July 7. Saturn's rings this month are tipped 6¡ from edge-on, our best view this year. An old crescent Moon has a spectacular predawn pairing with Venus on July 12. A waxing gibbous Moon appears near Jupiter on the nights of July 27 and 28. ********* SKYWATCHER'S DIARY: JULY 1996 ******** Monday, July 1 The Moon, just past Full, rises in ESE within 20 minutes after sunset across northern U.S., and within 35 minutes after sunset from Miami and SanDiego. An hour after sundown, Jupiter is about 12 degrees to its upper right. An hour before sunup on Tuesday, face SW to see Jupiter about 15 degrees to Moon's lower right. Tuesday, July 2 One and a quarter hours before sunrise on Wednesday, Venus is very low in ENE. Ever since Venus emerged as a morning star in late June, it has been approaching the first-magnitude star Aldebaran from lower left. On Wednesday morning they'll appear closest, 2.4 degrees apart. Thereafter, Venus widens its distance lower left of Aldebaran as both rise higher in the sky daily. Since Venus doesn't climb past Aldebaran, Tuesday's event is called a "quasi-conjunction." Wednesday, July 3 From northern U.S., the Moon, three days past full, rises within 2 hours after sunset, before the sky darkens completely. Starting Thursday, Moon will rise late enough to allow a brief window of very dark skies for viewing the Milky Way and Comet Hale-Bopp. For a Sky Calendar and chart with directions for locating the comet, send a long, self-addressed stamped envelope to: July Sky Calendar, Abrams Planetarium, Michigan State University, East Lansing, MI 48824. Thursday, July 4 Tonight we'll give detailed directions for locating Comet Hale-Bopp, which is expected to put on a fine display next March and April. Two hours after sunset, before Moon rises, begin with bright Jupiter low in SE to SSE. Within same binocular field, notice the 3rd-magnitude star Pi Sagittarii 4 degrees to Jupiter's left. The comet is a 6th-magnitude hazy patch 11 degrees above Pi. The only deep-sky object of similar brightness nearby is the compact star cluster Messier 11, just over 5 degrees to comet's upper left. Notice the 4th-magnitude star Alpha Scuti within 5 degrees upper right of comet. On July 15, Comet H-B will pass just 2.2 degrees to that star's lower right. Friday, July 5 On Saturday, 1-1/4 hours before sunrise, Saturn is the bright "star" well up in SE, 11 degrees to Moon's lower left. A telescope shows the rings tipped 6 degrees from edge-on. Bright Jupiter is sinking in SW. Brilliant Venus gleams low in ENE, with Aldebaran 2-1/2 degrees upper right and Mars 7 degrees left. Saturday, July 6 On Sunday 1-1/4 hours before sunup, look high in SE for Moon, just over half full, with Saturn 3 or 4 degrees to its lower right. Approaching Last Quarter, Moon is just over 90 degrees from the Sun and precedes it across the sky. Try to follow Moon until it sets just N of due west Sunday around midday (halfway from sunrise to sunset). Sunday, July 7 This week and next are great for viewing the Milky Way after nightfall! On Monday 1-1/4 hours before sunrise, Moon is high in ESE and slightly less than half full. Saturn is in SE, 17 degrees to Moon's upper right. Each morning for rest of this week, watch Moon move closer to the Sun. Can you predict on which morning the Moon will appear very close to Venus, the brilliant planet low in ENE? That beautiful conjunction should not be missed! Monday, July 8 Two hours after sunset, bright Jupiter is in SE to SSE. Second- magnitude Sigma, brightest star in the handle of the Teapot of Sagittarius, is just over 3 degrees below Jupiter. The 3rd-magnitude star Pi in the Teaspoon is just over 4 degrees left of Jupiter. Using binoculars, look for Comet Hale-Bopp, a 6th-magnitude hazy patch of light 12 degrees above Jupiter and Pi. Can you detect the comet with your unaided eye? Tuesday, July 9 On Wednesday, 1-1/2 hours before sunrise, find the crescent Moon in the east, with the Pleiades (Seven Sisters) star cluster 13 degrees to its left. Brilliant Venus is very low in ENE, about 23 degrees to Moon's lower left. From Venus, note Aldebaran, eye of Taurus, 3 degrees upper right, and fainter Mars 8 degrees lower left. Wednesday, July 10 On Thursday 1-1/2 hours before sunup, find the waning crescent Moon low, about 10 degrees north of due east. Venus is 11 degrees to Moon's lower left. Can you guess where the Moon will appear on Friday? Mars remains 8 degrees to Venus' lower left. The reddish fist-magnitude star Aldebaran and the V-shaped Hyades cluster lie between the Moon and Venus. The Pleiades cluster is upper left of Moon and 14 degrees above Aldebaran. Thursday, July 11 Don't miss Friday morning's striking pairing of the two brightest nighttime objects: the Moon and Venus. The appearance of the event will vary with observer's location: From Europe and North Africa, the Moon occults, or covers Venus several hours after sunrise, when they're high in the sky. With Venus near greatest brilliancy, the event will be easily seen with unaided eye, even in daylight. From Bermuda and islands of the eastern Caribbean, Venus is hidden behind the Moon as they rise in predawn, and then Venus makes a spectacular reappearance from behind the dimly earthlit side of the Moon. Observers in the U.S. should try to catch Venus and the Moon just after they've risen in ENE. This occurs between 2 and 2-1/2 hours before sunup depending on location. Thereafter, follow them until sunrise and beyond as they spread apart. Within the U.S., Moon and Venus will appear closest as seen from New England and New York, a few minutes after they've risen on Friday. Venus will appear less than 0.1 degree from the northern cusp, or point, of the crescent. An especially striking arrangement can be seen from along a line from North Carolina through the Virginias, Ohio, and Michigan: As soon as Moon's disk has completely risen, Venus is directly above the Moon, 0.1 degree above the Moon's dim earthlit upper edge from North Carolina, and 0.2 degree from Michigan. Seen from SW of that line, Moon has already gone past Venus by the time they rise, and the brilliant planet appears to the Moon's upper right. Here is the separation of Venus from Moon's dim upper edge as Moon's disk first appears completely above the horizon: Charleston SC 0.2 degree Denver CO 1.1 degrees Miami FL 0.4 degree Seattle WA 1.2 degrees Chicago IL 0.5 degree Los Angeles CA 1.7 degrees Kansas City MO 0.8 degree From all U.S. locations, the Moon slides eastward (lower left) of Venus after their encounter by about half a degree (about one Moon diameter) per hour. Friday, July 12 On Saturday an hour before sunrise, the last easy old crescent Moon is very low in ENE. Moon has moved about 13 degrees to Venus' lower left. Mars is about 8 degrees above Moon and 9 degrees lower left of Venus. Aldebaran is 4 degrees to Venus' upper right. Saturday, July 13 From northern U.S. on Sunday morning, the old Moon rises in bright twilight and is not likely to be seen. From southern states, use binoculars half an hour before sunup to scan the ENE twilight glow for a very thin Moon. Look 25 degrees lower left of Venus. Sunday, July 14 This week, Venus reaches its greatest brilliancy in the morning sky. Locate Venus in eastern sky as twilight brightens, then keep track of it until sunrise. Binoculars reveal a tiny crescent, about 0.6 arcminute across and about one-quarter full. On Monday the Moon will be New at 12:15 p.m. EDT (9:15 p.m. PDT). Passing well south of the Sun on Monday and then reaching its greatest distance from Earth for this year (252,648 miles) on Tuesday, the Moon climbs very slowly out of the Sun's glare and isn't likely to be seen until soon after sunset on Wednesday. Monday, July 15 In SSE two hours after sunset tonight, Comet Hale-Bopp is a hazy patch of about 6th magnitude, 13 degrees above Jupiter and 2.2 degrees lower right of a 4th-magnitude star, Alpha Scuti. The comet may be visible with unaided eye in very dark skies, and binoculars make it look larger and brighter. When you "star hop" to a target object, it's important to know the angular field diameter of your binoculars. To get a sense of magnitude and angular distance with unaided eye and through binoculars, look for the 2nd-mag star Sigma Sagittarii 3.5 degrees below Jupiter, and the 3rd-mag star Pi Sagittarii 5.2 degrees to Jupiter's left. How wide is your binocular field? Tuesday, July 16 Comet Hale-Bopp shifts its position against the stars from one night to the next this week by just over 1/3 of a degree. About two hours after sunset, use binoculars to locate the comet as a 6th-magnitude hazy patch 13 degrees above bright Jupiter. Center your binoculars on the comet, and note the 3.8-mag star Alpha Scuti 2.2 degrees upper left of the comet, and 4.7-mag Zeta Scuti 3 degrees right of Alpha and 2.4 degrees upper right of comet. On July 22 the comet will pass only 0.8 degree lower right of Zeta. The comet will shift a total of 5 degrees during July 16-31, 8 degrees during August, and 3 degrees during September. This summer and autumn, our Sky Calendar will follow the comet as it brightens and slowly drifts across the evening sky. Wednesday, July 17 Beginning 20 minutes after sunset, look for the thin crescent Moon very low, about 10 degrees north of due west. Don't be late, or you may miss it! Thursday, July 18 Within half an hour after sunset, the crescent Moon is very low, nearly due west. In the next half hour, using binoculars if necessary, look for Regulus, heart of Leo, about 6 degrees to Moon's upper right. For observers with a star atlas and a telescope or good binoculars, the 8th- mag planet Neptune during darkness hours tonight is 1.7 deg ESE of 5th-mag 56 Sagittarii, and 1.4 deg SSE of 6th-mag 57 Sgr. Friday, July 19 With the Moon still a thin crescent setting around nightfall, dark sky sites still offer excellent views of the Milky Way. Begin at nightfall with bright Jupiter in SSE and Antares in SSW. Between them and much lower lies a prominent close pair of stars marking the end of the Scorpion's tail, 2nd-mag Lambda with 3rd-mag Upsilon just 0.6 deg to its right. Between these stars and Jupiter lie eight stars of 2nd and 3rd magnitude forming the Teapot of Sagittarius. Its handle is below Jupiter. In summer and early fall, the Milky Way looks like steam rising from the spout of the Teapot! Scan the "steam" with binoculars. Along the Milky Way 14 deg above or upper right of Jupiter and 6 deg upper left of the Omega Nebula M17, is Comet Hale-Bopp! Tonight and Saturday from 9 p.m. until 11 p.m., if skies are clear, MSU Observatory will be open for viewing of Moon, Jupiter, Comet Hale-Bopp, and summer deep-sky objects. We encourage you to bring your binoculars! Saturday, July 20 Two hours after sunset, bright Jupiter is in SSE, and first-mag Antares is in SSW, 31 degrees to Jupiter's right. Look 24 deg left of Jupiter for a pair of stars, Alpha 2.4 deg above Beta, in Capricornus. Though of only 3rd and 4th magnitudes, Alpha and Beta Cap stand out compared to their faint surrounding stars. Binoculars or sharp naked eye reveals Alpha as a close double star of 0.1 degree separation. (Actually the two members of Alpha aren't related; one is much farther from us.) The 5.3- mag star Sigma Cap is 4.3 deg lower right of Beta Cap. As a check, there's a compact triangle of two 5th-mag stars and a 6th-mag, about 2 to 2-1/2 deg left of Sigma. Finally, 5.7-mag Uranus is 1.1 deg below Sigma. Bring binoculars for a session at MSU Observatory, 9-11 p.m. if skies are clear. Sunday, July 21 Tonight and next few evenings are ideal for using binoculars or a small telescope to view lunar craters and other surface features near the terminator, or Moon's day-night boundary. Monday, July 22 An hour after sunset, face SW to see Spica 2 to 3 degrees lower left of Moon. In predawn darkness hours Tuesday through next Sunday, watch for Delta Aquarid meteors after the Moon sets. The observing "window" gets narrower each morning as the Moon sets later. Tuesday, July 23 Calculate the time of your local midday (halfway between the times of your local sunrise and sunset). Within an hour later, look low, 15 to 20 degrees south of east, for the rising First Quarter Moon. It is half full, but called First Quarter because it follows the Sun across the sky today by 90 degrees, or one-quarter of a circle. Wednesday, July 24 One hour before sunup on Thursday and Friday mornings, look between E and ENE to find Mars nearly 11 degrees lower left of Venus. This is the farthest apart they'll be until Sept. 26. Between now and then, they'll come within 3 degrees of each other in early September, then spread apart again. Look also for Aldebaran 11 deg upper right of Venus, and Betelgeuse, shoulder of Orion, about 14 deg below Venus. Using binoculars, scan the horizon 10 deg right of Betelgeuse for Orion's belt, a vertical line of three stars. Look also for Rigel, Orion's foot, 9 deg right of the belt. Thursday, July 25 Locate the Moon in SSW 1-1/2 hours after sunset. Can you see the head of Scorpius, three stars of 2nd or 3rd magnitude in a slightly curved vertical line 2 to 9 degrees below the Moon? Binoculars help pick them out of the glare of the gibbous Moon. Brighter first-magnitude Antares, about 10 degrees to Moon's lower left, is easier to see. Friday, July 26 Face south an hour after sundown to spot Antares about 11 degrees lower right of Moon. This is the final weekend for public shows at Abrams Planetarium until mid-September. For more information, call our show info line at (517) 355-4672. Saturday, July 27 Moon is in SSE at dusk, with bright Jupiter about 9 degrees lower left. Comet Hale-Bopp is only 10 degrees upper left of the very bright Moon -- not a good night for viewing! Wait until August 2, and then Moon will rise late enough to allow a brief dark moonless interval for viewing the comet and the Milky Way. Each night thereafter the Moon will rise later, and the dark "window" will widen. Sunday, July 28 Face SE sky at dusk, and you can't miss bright Jupiter about 8 degrees to Moon's right. Monday, July 29 The Moon is Full overnight, at 6:35 a.m. EDT on Tuesday. Do tonight's rising Moon (in ESE just before sunset) and Tuesday morning's setting Moon (in WSW around sunrise) seem unusually large to you? If you think so, you'd be correct. At about 4 a.m. EDT on Tuesday, the Moon is 221,797 miles from Earth, its closest for the year! The Moon's disk tonight is 14 percent larger in angular diameter than it was two weeks ago. July's Full Moon is known as the Hay or Thunder Moon, according to Guy Ottewell. Tuesday, July 30 Tonight the Moon rises near the time of sunset across the northern part of the contiguous U.S., and several minutes after sunset seen from farther south in the U.S. In spite of its slightly greater distance from Earth tonight, the rising Moon may seem larger than on Monday evening, because the sky is darker during tonight's moonrise. Wednesday, July 31 Using binoculars about 40 minutes after sunset, from a place with an unobstructed view of the horizon about 15 degrees N of due west, search for Mercury and Regulus less than a degree apart. Mercury is the brighter and farther north. This pairing is higher and easier to see from southern states. From the latitude of East Lansing and farther north, the Moon rises less than 40 minutes later each night for the next week. It will rise nearly due east on Friday, and farther north each night until Aug. 9. ********** end of Skywatcher's Diary for July 1996 **********