The Skywatcher's Diary for May 2006 has been prepared by Robert C. Victor, formerly Staff Astronomer (now retired). 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 issue of the Sky Calendar is available over the Internet. It can be viewed via the World-Wide Web at http://www.pa.msu.edu/abrams/SkyCalendar/Index.html
If you would like a printed sample of the May issue, please send a long, self-addressed stamped envelope to:
May Sky Calendar
Abrams Planetarium
Michigan State University
East Lansing, MI 48824
Each month, the Department of Physics and Astronomy at Michigan State University makes the Skywatcher's Diary available over the Internet. It can be accessed at http://www.pa.msu.edu/abrams/SkyWatchersDiary/Diary.html
Current and back-issues of the Skywatcher's Diary are available in our
archives
at
http://www.pa.msu.edu/abrams/SkyWatchersDiary/Archives.html
ftp://www.pa.msu.edu/pub/swd/
May's evening planets: Jupiter reaches peak brilliance for year at mag. -2.5 as it attains all-night visibility at its opposition to the Sun on May 4. At dusk find Jupiter low in ESE, ascending through SE to SSE as month progresses. Jupiter is slowly retrograding, west away from 3rd-mag. Alpha Librae until early July. Saturn descends through WSW to W at dusk in May. At mag. +0.3 Saturn slightly outshines nearby Procyon. The Beehive star cluster in Cancer is in same binocular field as Saturn; watch planet creep eastward past S edge of that cluster in early June. Mars descends in west, while closing from nearly 25 degrees to within 9 degrees lower right of Saturn. Going eastward in Gemini, Mars passes 5 degrees S of 1.2-mag. Pollux on May 22 and 23. Compare Mars' brightness to the fainter northern twin, Castor of mag. 1.6. Bright Mercury emerges very low in WNW twilight late in month; see May 27-31.
Morning: Venus is low as dawn brightens, drifting from S to N of east as month progresses. Jupiter, opposite the Sun on May 4, sinks into WSW at dawn in May. Last chance until late spring 2007 to see Venus and Jupiter simultaneously!
COMET 73P/Schwassmann-Wachmann 3 split into fragments during its last two apparitions and is currently breaking up still further. Component C is the largest and brightest fragment, and data given under May 6-8 apply to it. On night of May 7-8, comet's C Component will appear between Beta and Gamma Lyrae, the pair of 3rd-mag. stars 2 degrees apart some 6 to 7.5 degrees SSE of Vega. After passing through the Summer Triangle, it comes within 0.08 a.u. (7 million miles) of Earth on May 12, but will likely be no brighter than mag. 5 at best, in a bright moonlit sky. For web links to a finder chart and updates on the comet, go to http://www.heavens-above.com
The Moon was New on April 27, passes First Quarter phase on night of May 4, Full on night of May 12, reaches Last Quarter phase on the morning of May 20, and passes New on night of May 26. Our natural satellite appears near naked-eye planets on the following dates: As a waxing crescent Moon near Mars on evening of May 1 and near Saturn on evening of May 3; as a waxing gibbous Moon, near Jupiter from dusk until dawn on night of May 11-12, one day before Full; and as a waning crescent Moon near Venus at dawn on morning of May 24. There's an extraordinary chance to see opposing crescent Moons within about 40 hours of each other on consecutive days: First, a waning crescent at dawn on May 26, and then an easier waxing crescent at dusk on May 27. See details under May 25-27. Back in the evening sky, a waxing crescent Moon passes Mercury on May 27, Mars on May 30, and Saturn on May 31.
Stars: In early May, look low in WSW in evening twilight for brightest nighttime star, Sirius. The Winter Triangle stars Sirius-Betelgeuse-Procyon get lower each evening. On what date will you last see all three?
Around nightfall throughout May, look high in the north for the well-known Big Dipper. Imagine its bowl to have a leaky bottom. Then the watery contents would pour onto the back of Leo the Lion, represented on our map by a Sickle (whose blade represents the mane of the Lion) and a triangle (representing the Lion's hindquarters). The star Regulus, at the handle of the Sickle, represents Leo's heart.
Extend a line connecting the Big Dipper's Pointer stars (the two stars in the front of the bowl) to point out Polaris, the North Star, always in the north. You can also use the Dipper to locate a much brighter but less well known star, Arcturus, by following the curve of the handle: "Follow the arc to Arcturus," which is shown on our map high in the east-southeast. To the lower right of Arcturus and lower left of Leo is the constellation Virgo, in SE to S at the time of our map. Virgo's brightest star, Spica, is easy to see low in the southeast, to the upper right of brilliant Jupiter. You can also find that star by extending the curve of the Big Dipper's handle on past Arcturus, and you'll "Drive a spike to Spica."
Leo and Virgo are constellations of the zodiac, the backdrop against which the Sun, Moon and planets are seen. In early May we see Libra, another zodiac constellation, and Jupiter, when we face away from the Sun, and so the Moon will be in their part of the sky for a couple of days around Full, which occurs on May 12.
Leo is facing west, toward two bright planets and a lineup of zodiac constellations. In order westward from Leo, they are: Cancer, the Crab, containing bright Saturn and the Beehive cluster of faint stars visible in the same binocular field; Gemini, containing the bright "Twin" stars, Pollux and Castor, and Mars. From May 14 until June 21, the Sun appears against the background of the next zodiacal constellation to the west, Taurus, the Bull. Only his horns remain above the map's west-northwest horizon. In the closing days of May, Mercury will appear there. In the opposite direction, in ESE to SE to the lower left of Jupiter, the head of Scorpius is just rising. Later in the evening, the star Antares, heart of the Scorpion, rises into view; see May 13 and 14.
The plane of the solar system or centerline of the zodiac in our May evening sky is quite well defined by the line connecting Mars, Saturn, and Jupiter extended toward both horizons. You'll notice that east of Saturn the line passes quite close to Regulus, then farther on to Spica and Jupiter in the southeast. The Twin stars Pollux and Castor, near Mars, lie a little north of the line. Betelgeuse, Orion's shoulder low in the west, and the little Dog Star Procyon following Orion across the sky are well south of the plane, while the Mother Goat star Capella in the northwest, the Bear-chaser star Arcturus high in ESE, and bright Vega low in the northeast all lie well to the north of the main plane of the solar system.
Following is a day-by-day guide to celestial happenings during May 2006. For drawings of many of these events, and an evening sky map, request a free sample copy of the Abrams Planetarium Sky Calendar by sending a self-addressed, stamped envelope to Sample Sky Calendar, Abrams Planetarium, Michigan State University, East Lansing, MI 48824. Or you can subscribe for $11 per year. We appreciate your subscriptions!
Facing west 1-1/2 hours after sunset these evenings, watch the Moon pass two naked-eye planets. On Mon. May 1, notice Mars 6 degrees to Moon's upper left. On Tues. May 2, Mars is 7 or 8 degrees below the Moon, while the Gemini Twins stars, Pollux and Castor, lie within 6 degrees above the Moon. On Wed. May 3, Saturn is within 6 degrees to Moon's left, while the Twins lie 7 to 12 degrees to Moon's lower right. (To help you estimate angular distances, remember the Twins are almost exactly 4.5 degrees apart.)
Moon is at First Quarter phase, half full tonight and 90 degrees or one-quarter circle from the Sun. Note Saturn 8 degrees to Moon's lower right. Also tonight, Jupiter is at opposition, 180 degrees from the Sun. Look for Jupiter low in ESE to SE at dusk, highest in S in middle of night, and low in SW to WSW at dawn. Use the position of Jupiter in the sky to tell the time of night!
An hour after sunset, the Moon is high in WSW to SW, with the star Regulus, heart of Leo, within 6 degrees to its lower left. These evenings are wonderful for observing lunar surface features through binoculars or a telescope.
Moon is high in SSW at nightfall, with Regulus 7 degrees to its right. Four solar system bodies, in order from W to E, Mars-Saturn-Moon-Jupiter, span 120 degrees across the sky. Tonight binoculars show the double star Alpha in Libra within 2 degrees below Jupiter, the Beehive cluster of stars about 2 degrees upper left of Saturn, and the crater Copernicus along the Moon's sunrise terminator (day-night boundary). Our best looks at Comet Schwassmann-Wachmann 3 speeding past Earth will be when it's nearly overhead in the dark moonless skies of Sunday through Tuesday mornings, May 7-9, after moonset and before morning twilight brightens. On Sunday morning, the comet may appear in binoculars and telescopes as a faint 6th-magnitude (fainter than previously expected) fuzzball just over 5 degrees south of the bright star Vega. (The Pointer stars in the bowl of the Big Dipper -- the ones used to find the North Star -- are separated by the same angle.)
At nightfall, look well up in the western sky for an attractive isosceles triangle formed by Mars and the Gemini Twin stars Pollux and Castor. The Twins are 4.5 degrees apart with Mars 10.5 degrees below them. Watch for changes in the shape of the triangle in coming weeks. Tonight a faint comet visible through binoculars or a telescope passes between the two 3rd-mag. stars Beta and Gamma in Lyra, two degrees apart, some 6 and 7.5 degrees SE of Vega. About 1-3/4 hours before sunup on Monday, the comet is very near Gamma Lyrae and about one-seventh of the way from Vega (nearly overhead), on a line toward Altair (high in SE).
Tuesday morning about 1-1/2 hours before sunrise is your last chance to catch a comet high in a dark moonless sky. First locate the Summer Triangle: Vega nearly overhead, Altair high in SE, and Deneb high in ENE. Nearly halfway from Vega to Altair and just within the Triangle, locate 3rd-mag. Albireo, the head of Cygnus the Swan and foot of the Northern Cross. The Comet may be visible in binoculars as a 6th-mag. fuzzy spot about 4 degrees N of that star. During May 10-15 the comet moves eastward about 6 degrees daily, but in a bright moonlit sky. The comet passes just over 7 million miles from Earth on May 12, unfortunately when the Moon is full.
At nightfall, look for the star Spica in SE, 11 degrees lower left of Moon and 20 degrees upper right of bright Jupiter. In west find Saturn with Mars 20 degrees lower right. The Twins are now within 10 degrees above Mars. The Mars-Saturn gap will narrow by half a degree daily until Mars overtakes Saturn on June 17.
Spica is occulted by the Moon in late afternoon from eastern U.S. Telescopes may show the star after its daytime reappearance at the Moon's bright upper edge, in Miami at 7:20 p.m. EDT, in Atlanta at 7:27 p.m., in East Lansing at 7:31 p.m., and in Boston at 7:37 p.m.
By 10 p.m. in East Lansing MI, the star is just over one degree from the Moon's edge. Bright Jupiter is then 18 degrees to Moon's lower left.
As the sky darkens, the nearly full Moon is in SE with Jupiter 7 degrees lower left. They'll be hardly any closer at dawn on Friday, when the setting Moon is 6 degrees below Jupiter.
Tonight's Full Moon rises in ESE very nearly as Sun sets in WNW. From many places in U.S. except the Northwest, skywatchers with unobstructed views can try to see Sun and Moon simultaneously. Notice bright Jupiter about 9 degrees above the Moon. As darkness fall tonight through June 14, binoculars show a quadrilateral for stars of 4th and 5th mag. surrounding Saturn and the Beehive cluster. The view may be fully enjoyed in a dark sky starting May 15, when the Moon rises after nightfall.
From northern U.S., the Moon rises one hour after sunset. Even an hour later, the Moon is only 7 degrees up in SE. Look for Antares, heart of Scorpius, 6 degrees lower left and bright Jupiter 22 degrees to Moon's upper right. About 1-1/4 hours before sunup on Sunday, Moon is low in SW, with Antares within 4 degrees upper left. After the Moon, the next brightest objects then visible are Venus very low in E and Jupiter low in WSW. On Sunday morning these two planets are 150 degrees apart.
Moon rises over two hours after sunset, and in another hour is still just 7 degrees up in SE. Look for the red supergiant star Antares 8 degrees to Moon's upper right.
This month's southernmost Moon rises over three hours after sunset and is still only about 7 degrees up in SE an hour later. From East Lansing and places at the same latitude (42.7 degrees N) the Moon reaches its high point, due south less than 18 degrees up, around the start of twilight on Tuesday morning. Near the Moon, note the 3rd-mag. stars Gamma and Delta in the spout of the Teapot of Sagittarius. Use binoculars to catch these stars in the glare of the Moon.
Tonight telescopes show all four of Jupiter's bright moons on the same side (east) of the planet.
Tonight, telescopes show all four of Jupiter's moons discovered by Galileo, two on each side of the planet. Look nightly to follow their changing arrangement.
Mercury is at superior conjunction today, on the far side of the Sun. By the end of next week, from places where mountains don't block the view, Mercury will begin to be visible very low in WNW during evening twilight.
As the sky darkens, Saturn is well up in W, with Mars now 15 degrees lower right, and the Gemini Twins Pollux and Castor 4.5 degrees apart some 5 to 9 degrees to Mars' upper right. Tonight all four of Jupiter's bright moons appear at their greatest distances to the side of Jupiter, and can be viewed with a steadily held pair of binoculars. In order from E to W, the five bodies are Callisto-Europa-Jupiter-Io-Ganymede. Can you tell that Ganymede is Jupiter's brightest satellite? In fact, it is the largest moon in the solar system.
About 1-1/4 hours before sunrise on Saturday, the Last Quarter Moon is half full in SE with the star Fomalhaut rising 18 degrees below. Venus is very low just N of E, while Jupiter is very low in WSW. This morning, Earth's orbital motion is carrying us toward Aquarius, 4 degrees above the Last Quarter Moon. We are overtaking slower moving Jupiter, so in coming weeks that planet will drop below our predawn western horizon, while faster moving Venus will circle around toward the far side of the Sun by late October.
For rest of May, both Jupiter and Saturn are simultaneously visible about 30 degrees up in evening twilight, their highest positions together for years to come. Set up telescopes and share wondrous views of Jupiter and four satellites discovered by Galileo, its dark cloud belts, and Saturn's rings and largest moon Titan. The time the planets appear at equal altitudes shifts 4 minutes earlier nightly. (From East Lansing, MI, Jupiter and Saturn are equally high tonight at 10:46 p.m. EDT.)
At nightfall tonight and Tuesday, look west to find Mars passing 5 degrees south (lower left) of Pollux, the brighter Gemini Twin. Still brighter Saturn is 13 degrees to Mars' upper left. Binoculars show the Beehive cluster just above Saturn. An hour before sunrise on Tuesday, face east to find brilliant Venus within 11 degrees lower left of the waning crescent Moon.
An hour before sunrise on Wednesday, look low just north of east for a beautiful sight: A young crescent Moon with Venus 4 degrees to its lower right.
An hour before sunrise on Thursday, watch for a thin old crescent Moon rising in ENE, 16 degrees to Venus' lower left.
On Friday about 1-1/4 hours before sunrise, Venus just N of E and Jupiter in WSW are 165 degrees apart. (At 4:49 a.m. EDT in East Lansing, MI, both are only 3 degrees up.) Can you find a place to view both simultaneously?
See rare "opposing crescent Moons" on consecutive days, on Friday at dawn and on Saturday at dusk. Conditions are very favorable for catching both crescents throughout the contiguous 48 United States. Data telling when and where to look for these very thin crescents surrounding the New Moon of Sat. May 27 at 1:26 a.m. EDT (Fri. May 26 at 10:26 p.m. PDT) are given here and in Saturday's text.
To search for the waning crescent on Friday morning, begin no later than at civil twilight (when the Sun is 6 degrees below the horizon), and continue until the Sun is 5 degrees below the horizon. The Sun's passage between those limits on May 26 and 27 takes just 5 minutes from southern U.S. For example from southern Florida, morning civil twilight occurs 25 minutes before sunrise, and by 20 minutes before sunrise the Sun is only 5 degrees down. From the latitude of Atlanta and Los Angeles, this passage also lasts about 5 minutes, but from 28 to 23 minutes before sunrise. Farther north, the passage is farther ahead of sunrise and takes longer. From Boston and East Lansing, the Sun's passage from 6 degrees to 5 degrees down lasts 7 minutes, from 34 to 27 minutes before sunup. And from the Northern Tier (latitude 49 degrees N), the passage lasts 8 minutes, from 40 to 32 minutes before sunup.
Example: From East Lansing, MI, morning civil twilight (Sun 6 degrees down) occurs at 5:32 a.m. EDT on Friday. At that time a very thin crescent Moon, just 19 hours 54 minutes before New, is visible in binoculars 29 degrees lower left of Venus and only 2 degrees up in ENE (azimuth 61 degrees). Seven minutes later, at 5:39 a.m., the Sun is 5 degrees down, the Moon is 19 hours 47 minutes before New, at azimuth 62 degrees, altitude nearly 3 degrees. At this later time, the Moon's elongation (angular distance from the Sun) is 10.6 degrees. If you spot this hairline crescent on Friday morning, then you've accomplished the first and more difficult task in the rare sighting of a pair of opposing lunar crescents on consecutive days. The second, easier crescent can be spotted soon after sunset on Saturday evening.
Here are data for several cities for Friday morning, including: Time when the Sun is 5 degrees down (remember to start looking several minutes earlier as described above), Moon's azimuth and altitude in degrees not including refraction, distance lower left of Venus, elongation, and age.
Boston 4:47 a.m. EDT, Moon Az. 62.8, Alt. 3.1, 28 deg LL of Venus, Elong. 11.0 deg, Age -20h 39m.
E Lansing 5:39 a.m. EDT, Moon Az. 62.2, Alt. 2.8, 29 deg LL of Venus, Elong. 10.6 deg, Age -19h 47m.
Miami FL 6:10 a.m. EDT, Moon Az. 67.2, Alt. 4.5, 30 deg LL of Venus, Elong. 10.2 deg., Age -19h 16m.
90W, 40N 5:11 a.m. CDT, Moon Az. 63.3, Alt. 3.0, 30 deg LL of Venus, Elong. 10.3 deg, Age -19h 15m.
Los Angeles 5:22 a.m. PDT, Moon Az. 64.6, Alt. 3.1, 31 deg LL of Venus, Elong. 9.2 deg, Age -17h 04m.
Seattle 4:49 a.m. PDT, Moon Az. 57.7, Alt 1.6, 30 deg LL of Venus, Elong. 9.6 deg., Age -17h 37m.
Mauna Kea 5:24 a.m. HST, Az. 66.0, Alt. 2.6, 32 deg LL of Venus, Elong 7.6 deg (difficult, near minimum possible elongation to see the crescent), Age -14h 02m. The theoretical westernmost location to see this crescent with optical aid is near long. 157.5 degrees W, lat. 15.9 degrees N, not far to the southwest of Hawaii. There, when the Sun is 5 degrees below the horizon, the Moon is 7.5 degrees directly above it (and hence 2.5 degrees above the horizon), at an age of -13h 47m.
We hope you spotted the old crescent Moon this morning (see May 25). The Moon can't be seen this evening, because it's New, nearly between Earth and Sun, at 10:26 p.m. PDT (1:26 a.m. EDT on Saturday morning). Your next chance to see the Moon will be early in evening twilight on Saturday, and if your sky is clear, it should be quite easy to catch the young crescent within 24 hours after New. Details tomorrow.
In East Lansing MI this evening at 9:32 p.m. EDT (27 minutes after sunset), a very thin crescent Moon is 5 degrees up in WNW (more accurately, 32 degrees N of due west). Through binoculars it appears as a very thin smile. At that time the Moon is 10.7 degrees upper left of the Sun, which is then 5 degrees below the horizon, and the Moon's age is 20.1 hours past New. As an extra bonus, the planet Mercury appears within 3 degrees to Moon's lower left. As the sky darkens, both Moon and Mercury may become visible to the unaided eye.
Here are data for several cities, including: The local time on Saturday when the Sun is 5 degrees down, Moon's azimuth and altitude in degrees not including refraction, elongation, and age. From Miami the Sun is 5 degrees below the horizon about 20 minutes after sunset, and it takes an additional 5 minutes until civil twilight (Sun 6 degrees down). From the Northern Tier of the U.S., Sun is 5 degrees down 32 minutes after sunset, and 8 minutes later civil twilight is reached. Since the Moon is still several degrees above the horizon then from all these locations, observations can continue as the sky darkens, and the young Moon and nearby Mercury will become easy even for the general public to notice with unaided eye. The theoretical easternmost location for spotting this crescent Moon with optical aid lies in the Mediterranean Sea, near long. 14.5 degrees E, lat. 38.1 degrees N. There, when the Sun is 5 degrees below the horizon, the Moon is 7.5 degrees directly above it (and hence 2.5 degrees above the horizon), at an age of +13h 14m.
Boston 8:37 p.m. EDT, Moon Az. 302.5, Alt. 4.9, Elong. 10.3 deg, Age +19h 11m.
E Lansing 9:32 p.m. EDT, Moon Az. 302.4, Alt. 5.3, Elong. 10.7 deg, Age +20h 06m.
Miami FL 8:26 p.m. EDT, Moon Az. 297.8, Alt. 5.1, Elong. 10.2 deg., Age +19h 00m.
90W, 40N 8:45 p.m. CDT, Moon Az. 301.1, Alt. 5.5, Elong. 10.8 deg, Age +20h 19m.
Los Angeles 8:19 p.m. PDT, Moon Az. 298.7, Alt. 6.5, Elong. 11.6 deg, Age +21h 53m.
Seattle 9:25 p.m. PDT, Moon Az. 304.5, Alt 5.9, Elong. 12.2 deg., Age +22h 59m.
Mauna Kea 7:15 p.m. HST, Az. 296.8, Alt. 7.4, Elong 12.5 deg, Age +23h 49m.
Half an hour after sunset, the nearly 2-day-old crescent Moon is an easy sight low in WNW with Mercury within 11 degrees to its lower right. Note earthshine on the Moon's dark side. Tonight the Moon sets farther north than on any other night in this lunar cycle.
Forty-five minutes after sunset, look for Mercury very low, 22 degrees lower right of the crescent Moon in WNW. Faint Mars is 14 degrees to Moon's upper left. Saturn is now within 10 degrees upper left of Mars.
As evening sky darkens, locate faint Mars about 3 degrees to Moon's left, and the Gemini Twins Pollux and Castor about 4 to 8 degrees to Moon's right. Tonight Mars-Pollux-Castor lie in a straight line.
This evening within an hour after sunset, five solar system bodies, in order Mercury, Mars, Moon with Saturn, and Jupiter, span 135 degrees across the sky from WNW to SE. The bright "star" below the Moon tonight is Saturn. As the sky darkens, binoculars show the Beehive star cluster just to Saturn's upper right.
|
Please send any comments, suggestions, or questions to Shane Horvatin: hovati3@msu.edu |