The Dudley Observatory

This is the Skywatch Line for Monday, May 1.
by Joe Slomka

The Sun sets tonight at 7:55, with night falling at 9:47 PM. Dawn breaks at 3:57 and ends with sunrise at 5:48.

The rapid movement of several heavenly bodies marks the beginning of May. The four-day-old Moon, a thin crescent, is already up by sunset and lies about seven degrees from Mars. Over the course of the month our Moon passes: Mars, Castor and Pollux (the brightest stars in Gemini), Saturn and Regulus (the brightest star in Leo).

Mars does a lot of traveling itself this month. Usually planets slowly amble across the heavens. But the Red Planet, this month, zips through Gemini and comes quite close to Saturn.
Saturn is slowly heading eastward through the Beehive star cluster. This illusion is due to Mars' relative proximity to Earth as opposed to Saturn's three times distance.

By twilight's end, Jupiter blazes low in the southeast. Our Solar System's largest planet reaches opposition this week. That means that Jupiter rises at sunset and sets at sunrise. Binocular viewers can easily see the famous moons that Galileo discovered. Telescope users must wait a few hours for Jupiter to reveal its intricate weather systems. Recently, a smaller one joined its Great Red Spot. Is this new storm a permanent or temporary fixture? Planetary scientists are studying this novelty for clues on Jovian weather. By midnight, Jupiter is ideally placed for observation, while the Moon, Mars and Saturn prepare to set.

Comet Schwassman-Wachmann3 is now racing northward. Observers with rural skies and telescopes can find it near the eastern side of Hercules.

Jupiter lies West of the dim constellation, Libra. It has a diamond shape. Originally part of the Scorpion's claws, legend is that Julius Caesar cut the claws and renamed the constellation Libra, the Scales of Justice, to honor his legal reforms.

The star on the diamond's top is named Zuben Eschemali (The Northern Claw). Jupiter lies next to Zuben El Genubi (the Southern Claw), which is the constellation's brightest star. Zuben El Genubi lies about 65 light-years away, and 25 times brighter than our Sun.

This is the Dudley Observatory Skywatch Line for Tuesday, May 2nd, 2006, written by Steven Russo, Planetarium Manager of the Suits-Bueche Planetarium at the Schenectady Museum.

Sunrise today was at 5:47 AM, and it set tonight at 7:56 PM. Sunrise tomorrow will be at 5:57 AM and Sunset will be at 7:57 PM.

The Moon is in a waxing crescent phase today, with the First Quarter Moon on Friday. Today it rose at 9:10 AM, and it will set at 12:49 AM tomorrow morning. Tonight the Moon will be just above Mars, while tomorrow night, it will be just below Saturn.

With astronomical twilight ending at 9:45, it isn’t really dark until 10 PM. By that time, Leo the Lion is due south, and almost overhead, and the Big Dipper is just about directly overhead.

The planet Mars, looking like an orange-yellowish star, is in Gemini the Twins, and the planet Saturn is high up in the west by the time darkness arrives. It is located in the Constellation of Cancer, near the famous cluster of stars known as the “Beehive”.

The Planet Jupiter is in the east by 10 PM, in the constellation of Libra, and is also visible low in the west before Sunrise. Venus, the brightest object in the Solar System after the Sun and the Moon, is in the east before Sunrise.

This Saturday is National Astronomy Day. Come out to the Planetarium between Noon and 4 PM, and meet members of the Dudley Observatory, The Albany Area Amateur Astronomers, The Saratoga County Astronomy Club, and the Henry Hudson Planetarium. Chat with these groups about telescopes, observing, and their clubs. Solar Observing will take place weather permitting, and you can take home star charts and other information.

Public Programs at the Suits-Bueche Planetarium at the Schenectady

Museum, are on Saturdays and Sundays at 1, 2, and 3 P. M. The 1:00 program is “The Sky Above Mister Rogers Neighborhood”, a program for young people. At 2 P. M. is “Cowboy Astronomer”, and at 3 P. M. is a live narration of the Winter Sky. “Cowboy Astronomer” also plays Tuesday through Fridays at 2 PM.

Skywatch Line May 3, 2006
by Bernard Forman

The Sun sets tonight at 7:57 PM. The waxing crescent moon rises at 10:15 AM and sets tomorrow morning at 2:08 AM. The moon is in the constellation Cancer, the Crab, close to both the Beehive Cluster and Saturn. Preceding the moon and Saturn toward the horizon is Mars, which sets at 12:41 AM, Thursday morning. Also prominent is Jupiter, shining at minus two and a half magnitude in the constellation Libra.

By 10:00 PM tonight Leo, the Lion, is already past the meridian. Due south is the “Realm of the Galaxies,” the Virgo galaxy cluster, which spills over into Coma Berenices. If you point a telescope halfway along a line from Denebola, or Beta Leonis, to Epsilon Virginis, also known as Vindemiatrix, a third magnitude star approximately eighteen degrees to its east, you would have difficulty not seeing any galaxies. For the dedicated amateur, the difficulty, and the fun, is in identifying which galaxies are which. The Virgo cluster lies approximately forty-five million light years away and contains about three thousand galaxies, dozens of which are visible in modest size amateur telescopes.

Looking toward the east, we next come to the constellation Bootes, the Herdsman, which looks more like a kite or an ice cream cone. Bootes is easily found by locating Arcturus using the handle of the Big Dipper. Every amateur knows to follow the arc to Arcturus. Arcturus, a zero magnitude orange giant star, is the brightest star in the sky’s northern hemisphere and the fourth brightest star in the entire sky.

To the east of Bootes, we next come to Corona Borealis, the Northern Crown. The constellation consists of an arc of seven stars, six of which are fourth magnitude, with a second magnitude star representing the central gem in the crown. Corona Boreales is also home to a galaxy cluster but, unlike the Virgo cluster, its galaxies are so distant as to not be targets for amateur telescopes.

Finally, east of Corona Borealis, we start to see the constellations of summer. By 10:00 PM, Hercules has already risen well above the eastern horizon. Hercules is a large, though not particularly prominent, constellation. The most recognizable part of Hercules is a group of four stars commonly referred to as the Keystone, as its shape resembles the topmost stone in a masonry arch. Hercules is best known for one of the finest globular clusters in the entire sky, M 13. Hercules also contains another fine globular cluster, M 92.

Soon, we will be observing the constellations of summer and the numerous globular clusters so prominent in that season.

Skywatch line for Thursday, May 4, 2006
by Ray Bogucki

Halley's Comet is one of the oldest and best-known of all comets. It has made 30 appearances at roughly 76 year intervals since it was first recorded in 239 B.C. The last appearance was in 1986 and is next expected in the year 2062. Halley's Comet follows a very long elongated elliptical orbit around the Sun. Traveling from its farthest point from the Sun, out near the orbit of Neptune, it swings in very close to the Sun between the orbits of the innermost planets, Mercury and Venus. It passes through the Earth's orbit on its way in to perihelion, its closest approach to the Sun, and again, 5 months later, upon its departure. The comet is a potato-shaped chunk of ice about 10 miles long by 5 miles wide. It is imbedded with small particles of rock and dust that may have formed from the interstellar cloud before the planets formed. During the few months when the comet is close to the Sun, the searing heat vaporizes some of the ice, thus releasing millions of tons of dust and small particles which then accompany the comet in its orbit. After many passes close to the Sun, the entire path of the comet becomes littered with this small debris.

Tonight, the Earth will pass through the thickest part of the debris left by Halley's Comet. The collisions of the particles with molecules in our upper atmosphere will give rise to the eta-Aquarid meteor shower. The best time to view the meteor shower will be from 2 a.m. Friday morning, after the first quarter Moon has set, and about 4:30 a.m. when the morning twilight will begin to brighten the sky. The eta-Aquarids are very fast-moving with particles entering our atmosphere at about 40 miles/sec. With luck, you should spot several dozen meteors per hour. We will pass through the second Halley's crossing next October when we will experience the Orionid meteor showers.

At this time, a much smaller, but closer, comet with the designation 73P/Schwassmann-Wachmann 3 (S-W3) is traveling across our late evening sky. It is currently moving west through the western part of the constellation Hercules, heading toward the Ring Nebula in Lyra. It is just about naked-eye visible in magnitude, but the light from the waxing Moon will require the use of binoculars. At about 11 p.m. Sunday night, telescope viewers can watch S-W3 pass within a few arc-minutes of the Ring Nebula, moving about one Moon-width every two hours. Its path through the stars is clearly displayed in the May, 2006 issue of Sky & Telescope magazine on page 60.

The Sun sets at 8:04 PM; night falls at 9:59. The eight-day-old Moon remains up most of the night. Dawn breaks at 3:44 AM, ending with sunrise at 5:40.

At twilight, the Moon, Saturn and Mars occupy center stage. Mars' red color easily identifies the planet. Mars continues to chase after Saturn. Mars finds itself between the knees of Gemini. Throughout the month, Mars proceeds eastward.

Saturn drifts eastward also; and closes in on the Beehive star cluster, two degrees away. Even if you do not own a telescope or binoculars, these planetary motions are apparent to the naked eye observer over the month.

By nightfall, Jupiter lies low in the southeastern constellation of Libra. Jupiter's four moons are easily seen in binoculars; a few hours later, a telescope shows Jupiter's weather bands and the Great Red Spot, a gigantic hurricane.

By midnight, constellations Hercules and Lyra have risen. By one AM, Lyra is high enough to show Comet Schwassman-Wachmann 3. The comet is not living up to brightness predictions, but should be visible in binoculars under dark skies. One of the reasons for the comet's faintness is the fact that it is breaking up. This is not new; Comet Shoemaker-Levy broke into twenty pieces before impacting Jupiter in 1994. Other comets have broken up due to the immense gravity of Jupiter or the Sun. However, this comet is breaking almost daily. Observers count about twenty fragments, most very faint.
If you have dark skies, look towards Lyra. The comet travels in a straight line between Lyra and Albireo, the bright star in Cygnus' tail. It should appear as a faint smudge; this smudge should move noticeably after an hour or so. The comet is making its closest approach to Earth this week. This is a very close approach indeed. Even so, this puts the comet at six times the Earth-Moon distance. The Moon also interferes; it approaches "Full" just as the comet comes closest. Even if it is not as spectacular as past comets, this comet provides important clues to the makeup of these mysterious space travelers.

This is the Dudley Observatory Skywatch Line for Tuesday, May 9th, 2006, written by Steven Russo, Planetarium Manager of the Suits-Bueche Planetarium at the Schenectady Museum.

Sunrise today was at 5:40 AM, and it set tonight at 8:03 PM. Sunrise tomorrow will be at 5:57 AM and Sunset will be at 7:57 PM.

The Moon is in a waxing gibbous phase today, with the Full Moon on Saturday. Today it rose at 4:37 PM, and it will set tomorrow at 4:12 AM. The Moon will be near Jupiter on Thursday evening.

With astronomical twilight ending at 9:45, it isn’t really dark until 10 PM. By that time, Leo the Lion is due south, slightly towards the west, and almost overhead, and the Big Dipper is just about directly overhead.

The planet Mars, looking like an orange-yellowish star, is in Gemini the Twins, moving more towards Saturn by mid month. Saturn is high up in the west by the time darkness arrives. It is located in the Constellation of Cancer, near the famous cluster of stars known as the “Beehive”.

Public Programs at the Suits-Bueche Planetarium at the Schenectady Museum, are on Saturdays and Sundays at 1, 2, and 3 P. M. The 1:00 program is “The Sky Above Mister Rogers Neighborhood”, a program for young people. At 2 P. M. is “Cowboy Astronomer”, and at 3 P. M. is a live narration of the Winter Sky. “Cowboy Astronomer” also plays Tuesday through Fridays at 2 PM.

The Sun sets tonight at 8:05 PM. The waxing gibbous moon rises at 5:40 PM and sets tomorrow morning at 4:31 AM.

The moon passes in front of, or occults, Spica in the constellation Virgo at 8:00 PM tonight. Although the sky will not be dark Spica, or Alpha Virginis, is a first magnitude star so it should be visible in binoculars.

Mars, at slightly brighter than second magnitude, is in Gemini, and sets at 12:30 AM Thursday morning, followed an hour later by zero magnitude Saturn in the constellation Cancer.

Jupiter rises at 7:17 PM in the constellation Libra. At minus two and a half magnitude, Jupiter is, except for the moon, the brightest object in the sky. Jupiter was at opposition on May 4 and is at its highest after midnight.

By 10:00 PM Orion has already set. In the south, Leo, the Lion, is past the meridian. Due south is the Realm of the Galaxies, that area between Denebola, in Leo, and Vindemiatrix, in Virgo, where we find the Virgo galaxy cluster. Unfortunately, even if the sky is, miraculously, clear, the moon’s light will interfere with the view.

In the east we are starting to see the constellations of summer. Hercules is well above the horizon, with Ophiuchus below it. East of Hercules we find the constellation Lyra, the Lyre, and Cygnus, the Swan, just peeking over the horizon.

While Hercules may best be known for its two prominent globular clusters, M 13 and M 92, Ophiuchus contains more globular clusters in Messier’s famous catalogue of deep sky objects, and numerous non Messier globular clusters as well. The southern portion of Ophiuchus also contains rich Milky Way star fields. The rich Milky Way and the globular clusters are indications that the constellation lies in the direction of the center of our galaxy.

Skywatch line for Thursday, May 11, 2006
by Ray Bogucki

Most people interested in astronomy recall the period of several days in July 1994, when a long string of fragments of the Comet Shoemaker-Levy 9 collided in spectacular fashion with the giant gas planet, Jupiter. S-L 9 had been discovered by Eugene and Carolyn Shoemaker and David Levy on March 24, 1993. Calculation of the comet's orbit showed that it must have passed very close to Jupiter on July 7, 1992, on its way into the inner solar system. The unequal forces exerted on the closer and father parts of the comet by Jupiter's large gravitational field had broken the fragile object into many fragments. Large telescopes confirmed that S-L 9 was, in fact, a long string of fragments and were headed directly toward Jupiter. The final string of collisions of the fragments were recorded with thousands of spectacular photos.

The lesser known comet 73P/Schwassmann-Wachmann 3 (S-W3) that is currently flying across our night sky underwent a similar fragmentation in 1995 during its pass through the inner Solar System. Comet S-W 3 was discovered in 1930. Its orbital period was calculated to be a little over five years. The next several passes of S-W 3 around the Sun were not observed although many astronomers searched for it. Then, in 1979, the comet was recovered by an alert observer at the Perth Observatory in Australia. It has been seen at 5.4 year intervals since then. During the 1995 perihelion pass, this relatively faint comet was observed by amateur astronomers to brighten suddenly by a factor of 100 times. Large telescopes were able to find that several fragments had formed within the coma or dust cloud surrounding the comet's head. During the 2000-2001 pass, telescopes clearly showed several fragments following each other in line. During the current passage, fragment C, the brightest fragment, passed the Ring nebula in Lyra last Sunday. It will pass closest to Earth tomorrow, on May 12, in the faint constellation Vulpecula, at a distance of only 7 million miles. It should be visible with binoculars for several days on either side of closest approach, but the bright Moon will interfere. By late May, S-W 3 will be rising at the beginning of morning twilight as it passes through the constellations Pisces and Cetus. Consult the May issue of Sky & Telescope magazine, page 60, for a detailed view of the path of fragment C. Fainter fragment B, which occasionally shows sudden bright outbursts, is following the same path about a day behind, and a few degrees north of fragment C. Large telescopes have detected about 60 smaller fragments of S-W 3.

The Sun sets at 8:11 PM, with night falling two hours later. Dawn breaks at 3:32 tomorrow morning, ending with sunrise at 5:32.

As the sky darkens, Mars and Saturn continue to dominate the darkening sky. They are moderately high in the southwestern sky. Mars is an indistinct reddish dot; but Saturn is bright and a great sight in a telescope.

Saturn's Moon Titan, visible in amateur telescopes, is generating excitement among planetary specialists. The Cassini radar mapped giant dunes, some a thousand miles long.
These resemble those of the Sahara or Saudi Arabia. Apparently gentle winds turn a rain of methane into these giant formations.

Jupiter lies low in the southeast. As it gets higher, binoculars show its famous four Galilean moons. A telescope shows not only the four moons, but views of its weather systems. At about 10:18 PM, the Great Red Spot should be ideally situated for observation in a telescope. The Great Red Spot is a hurricane that has been observed for about 300 years. Recently, amateurs discovered that a series of smaller storms merged to form a smaller Red Spot just below and behind the Great Red Spot.
"Red Spot Junior," as it is now called, is now subject to intense study by planetary scientists. Why did the storms merge and become a giant red storm is a major mystery. "Red Spot Junior" will help to unravel the mystery of Jupiter's climate, and also reveal clues as to our own planet's weather.

Midnight finds Mars and Saturn setting, while Jupiter is ideally situated for observation.

Dawn finds Jupiter preparing to set and the nearly full Moon low in the southeast. Even though the Moon is so bright, reports are that the remnants of Comet Schwassmann-Wachmann are bright, despite the Moon. The comet pieces can be found in between the neck of Pegasus and its body, formed by the Great Square.

Venus shines brightly shortly before Sunrise. The planet, in a telescope, appears about three-quarters illuminated. The Moon lies low in the southwest, preparing to set.

This is the Dudley Observatory Skywatch Line for Tuesday, May 16th, 2006, written by Steven Russo, Planetarium Manager of the Suits-Bueche Planetarium at the Schenectady Museum.

Sunrise today was at 5:32 AM, and it set tonight at 8:11 PM. Sunrise tomorrow will be at 5:31 AM and Sunset will be at 8:12 PM.

The Moon is in a waning gibbous phase today, with the Last Quarter Moon on Saturday. It actually set today at 7:40 AM, and will rise a little after midnight tonight.

With astronomical twilight ending just after 10 PM, it isn’t really dark until after that time.10 PM. After that, look for Leo the Lion high up in the south, and look for the Big Dipper just about directly overhead.

The Sun sets tonight at 8:12 PM. The waning gibbous moon doesn’t rise until 1:02 AM Thursday morning. The moon was full last Saturday; last quarter moon occurs next Saturday.

Mars, in Gemini, sets soon after midnight, followed by zero magnitude Saturn, in Cancer, at 1:05 AM. Jupiter was at opposition earlier this month and is, accordingly, better placed for viewing, transiting the meridian just before midnight. Of course, a Spring opposition means that the planet is relatively low in the sky forcing us to view the planet through more of earth’s atmosphere. To view Jupiter with a telescope, wait until it is due south when it is at its highest, about thirty-three degrees above the horizon.

At 10:00 PM tonight, most of the Winter constellations are out of view, only Gemini and Auriga being, for the time being, above the horizon low in the west. Of the Spring constellations, Leo is now west of the meridian, with Coma Berenices, Virgo and Bootes to the east. Now is an excellent time to follow long, meandering Hydra, the Water Snake, all the way from its head, made up of a group of six stars below the constellation Cancer, to the end of its tale, below and to the east of Spica, in the constellation Virgo. Hydra, although the largest constellation in the sky, is not prominent. Its brightest star, Alphard, or Alpha Hydrae, is a second magnitude star that marks the snake’s heart.

Despite its size, Hydra contains only three objects in Messier’s famous catalogue. M 83 is a large, face on spiral galaxy visible in small telescopes and M 48 is a large open cluster of about eighty stars just visible without optical aid under clear, dark skies and a fine sight in binoculars. Neither object is particularly close to the line of stars forming the snake. In contrast, M 68 is a globular cluster that lies along the line connecting Alphard and gamma Hydrae, a third magnitude yellow giant to the east. Even binoculars show that it is not a star.

Finally, Hydra contains a famous object not on Messier’s list, the Ghost of Jupiter nebula. The Ghost of Jupiter is a planetary nebula described by some as pale green and by others as pale blue. In actuality, it is somewhat smaller than the planet Jupiter. Any sixth magnitude star atlas will help you find it, along with the other deep sky objects in Hydra.

Skywatch line for Thursday, May 18, 2006
by Ray Bogucki

Four of the five bright planets are currently visible at some time during the night. We can begin a review of the status of our Solar System siblings by considering the one that is not visible. Mercury, the innermost planet, passes behind the Sun tonight at superior conjunction and is completely obscured by the Sun's brilliance. Yet, such is the speed of this planet, named after the winged messenger of the ancient Roman gods, that in just nine days, on Saturday, May 27, it will have moved far enough east of the Sun to be visible low above the west-northwestern horizon, setting right beside the very young crescent Moon about 40 minutes after sunset. It will remain visible through June, setting at mid-June a full hour and a half after the Sun.
Our nearest planetary neighbor, Venus, is currently a brilliant morning star, rising in the east almost two hours before the Sun at the first hint of morning twilight. It will continue this routine all through the summer until September when it will rapidly approach the Sun and become lost in the Sun's glare as it prepares to pass behind the Sun in late October.
Last November, our nearest outer neighbor, Mars, was at its closest approach to Earth at 43 million miles when we were on the same side of our respective orbits. It showed a large disc of 20 arc-seconds and shone with a bright magnitude of minus 2.3. We have raced away since then so that Mars now lies 190 million miles away and has shrunk in size to only 4.5 arc seconds. It shines with the modest magnitude of 1.5 in the constellation Gemini where it is rapidly approaching Saturn in nearby Cancer.
Jupiter was at opposition earlier this month, rising in the east as the Sun set in the west. Now it rises before sunset and lies low in the southeast at nightfall. Because it lies 14 degrees south of the celestial equator it is not very high in the southern sky even when it transits about midnight. Next week, about an hour before sunrise you can see the two brightest planets at opposite sides of the sky, with Venus rising just above the eastern horizon while Jupiter is about to set at the western horizon.
The majestic ringed planet Saturn, still flirting with the Beehive Cluster, M44, shines about 30 degrees up in the west at nightfall. It is about 15 degrees above and to the left of Mars but much brighter, and sets about 4 hours after the Sun. Its rings are tilted open toward the Earth and it still presents a beautiful image in a telescope.
Finally, the much fainter, distant planet, Uranus, should be possible to spot with binoculars about 4 a.m. Sunday morning. Search about two Moon widths above and a bit to the left, or east, of the waning crescent Moon low in the southeast. Uranus will appear as a pale blue dot, not as a stellar point.

This is the Skywatch Line for Monday, May 22
by Joe Slomka

The Sun sets tonight at 8:18; night falls at 10:23 PM. Dawn breaks at 3:21 tomorrow and ends with sunrise at 5:25 AM.

At sunset, three planets shine amid the darkening sky. Saturn and Mars are high in the southwest. Both are relatively insignificant amid the stars. Saturn still exhibits its beautiful ring system to the telescope observer.

Mars is a pale red dot approximately the same brightness of the two brightest stars of Gemini, Castor and Pollux. Over the week, note Mars' progress across Gemini. Mars forms a line with Castor and Pollux by week's end, as it chases after Saturn.

Jupiter appears low in the southeast at sunset, and remains low all night. By 11 PM, Jupiter lies due south. If you have a telescope, observe Jupiter. The Great Red Spot, a gigantic hurricane, is visible in the planet's center. In about an hour, "Red Spot Junior" replaces it. "Red Spot Junior" is a recent addition to Jupiter's features, having been discovered a few months ago. This is a lesser storm than its bigger brother. Will it persist, merge with the Great Spot, or weaken and die? At the same time, another event is taking place. The Moon Io casts its shadow on Jupiter. The simultaneous view of all three is unusual.

Dawn finds Saturn and Mars already set, with Jupiter preparing to set. Comet Schwassmann-Wachmann 3 is low in the eastern sky. It should still be visible to binocular users before the sky becomes too bright. The comet is found just below the Circlet of Pisces, which is, in turn, below Pegasus.

Gemini is an ancient constellation. The constellation was recognized as "Twins" by many cultures. Castor and Pollux, in Greek legends, were the sons of a mortal and Zeus. They crewed the legendary Argonaut. Ancient sailors prayed to them for a safe voyage. The phrase "By Jiminy" harks back to an ancient oath. The stars are approximately equally bright. In 1803, the astronomer Herschel discovered Castor to be a binary, two stars orbiting each other. This was the first binary to be discovered.

This is the Dudley Observatory Skywatch Line for Tuesday, May 23rd, 2006, written by Steven Russo, Planetarium Manager of the Suits-Bueche Planetarium at the Schenectady Museum.

Sunrise today was at 5:26 AM, and it set tonight at 8:18 PM. Sunrise tomorrow will be at 5:25 AM and Sunset will be at 8:19 PM.

The Moon is in a waning crescent phase today, with the New Moon on Saturday. It actually rose today at 3:12 this morning, and set at 4:27 this evening. Tomorrow it will rise at 3:35 AM, and will set at 5:44 PM.

With the days getting longer, it isn’t really dark until after 10 PM. After that, look for Leo the Lion high up in the south, and towards the west. The Big Dipper is just about directly overhead. The stars of Summer are beginning to make an appearance, with Cygnus the Swan low on the north east horizon.

The planet Mars, looking like an orange-yellowish star, is in Gemini the Twins, low in the west after darkness. At the same time, Saturn is high up in the west. It is located in the Constellation of Cancer, near the famous cluster of stars known as the “Beehive”.

The Planet Jupiter is in the east in the constellation of Libra, and is also visible low in the west before Sunrise. Venus, the brightest object in the Solar System after the Sun and the Moon, is in the east before Sunrise, but lower than a month ago.

The Sun sets tonight at 8:19 PM. The waning crescent moon sets at 5:19 PM and rises tomorrow morning at 4:10 AM. New moon occurs early Saturday morning.

Looking toward the west tonight Mars, in Gemini, sets just after midnight, followed by Saturn, in Cancer, which sets at 12:39 AM. Jupiter, in Libra is prominent toward the south, transiting the meridian at 11:22 PM. At almost minus two and a half magnitude, Jupiter is unmistakable as the brightest object in the nighttime sky. Even a relatively small telescope will show two bands on an obviously compressed globe, as well as the four Galilean moons. If less than four moons are visible, then the missing moon is either behind or directly in front of the planet.

By 10:00 PM tonight, several of the summer constellations are already above the horizon in the east. With the moon not a factor, from a dark location the Milky Way should become more obvious throughout the night. We will have to wait several hours before the Milky Way, and the constellations it passes through, is well placed.

Prominent south of the celestial pole marked by Polaris is Ursa Major, or the Great Bear. Although the third largest constellation in the sky, most people are only familiar with its central feature, the asterism commonly known as the Big Dipper. The Big Dipper, known to our British friends as the Plough, is probably the most familiar of star patterns in the entire sky. Two stars in the bowl, Merak and Dubhe, are used as pointers to find Polaris. The other two bowl stars, Megrez and Phecda, also known as Phad, point to Regulus in Leo. The stars in the handle are employed to find Arcturus in the constellation Bootes and, moving past Arcturus, Spica in the constellation Virgo.

The star at the crook of the dipper’s handle is a famous double star, Mizar and Alcor. While both may be separated visually, Mizar and Alcor are not a true binary star system. However, a small telescope shows a gravitationally related companion.

Ursa Major contains several deep sky objects in Messier’s famous catalog. Perhaps the most prominent are two galaxies visible in the same telescopic field of view, M 81 and M 82. M 81, at seventh magnitude, is one of the brightest galaxies in the sky, although it is rather large and thus has a low surface brightness. M 82, though dimmer, is smaller and actually appears more prominent. Both are spiral galaxies, although M 82 is seen edge on, creating an interesting contrast with M 81.

If you get to a star party this weekend, you are sure to see M 81 and M 82 in several telescopes.

Skywatch line for Thursday, May 25, 2006
by Ray Bogucki

Looking high overhead at dusk, we find the Big Dipper at the highest point of its circumpolar motion. If we follow the arc of the handle of the dipper, away from the bowl, we arrive at a very bright yellow-orange star, Arcturus, in the constellation Bootes the Herdsman. At a magnitude slightly brighter than zero, Arcturus is arguably the brightest star in the northern hemisphere. If we continue the curve of the arc in the same direction, we come to the bright white first-magnitude star, Spica, in the constellation Virgo. To the west, or concave side of this long curved arc, the sky is curiously dark. This area near the zenith contains the north galactic pole, the northern axis upon which the spiral arms of our galaxy, marked by the Milky Way, appear to rotate. When we look up, in May, our line of sight is perpendicular to the galactic plane and is thus free of the huge gas and dust clouds that litter the spiral arms of our galaxy. Our line of sight encounters few stars before bursting through the edge of our galaxy and gazing into the unobscured depths of the cosmos.
At about fifty-million light years out, we encounter an astonishing sight. A large cluster of thousands of galaxies appears to be spilling southward down the sky from the Big Dipper, through the constellations Canes Venatici and Coma Berenices, and into its densest grouping in Virgo.
This grouping is known as the Virgo Cluster and our own Milky Way Galaxy and our relatively near neighbor, at 3 million light years, the Andromeda Galaxy, are considered to be outlying members of this cluster. One bright member of this cluster, lying about 11 degrees west of Spica, and accessible in a moderate-sized telescope, is known as M104, the Sombrero Galaxy. The name arises from the large central bulge of light, seen as the crown of the hat, surrounded by a dark lane of galactic dust which is seen as the brim of the hat, tilted slightly toward the line of sight of the viewer. This is a rewarding object to find and study.
About 14 degrees northwest of Spica lies an elegant close double star, gamma Virginis, with the name Porrima. When I first viewed Porrima about 10 years ago, it was a beautiful pair of matched stars with a comfortable but close separation. Recently, when I revisited this star, I was surprised to experience great difficulty in splitting the pair. This is an orbiting pair that swings from a wide separation of 6 arc-seconds to a periastron separation of only 0.3 arc-seconds. Its orbital period is about 170 years and it will reach periastron, or closest approach to each other, next year, when it will appear as a single star to backyard telescopes. If you can still split this star, your telescope has excellent resolution. If not, wait a few years when the separation will again be opening up.

This is the Dudley Observatory Skywatch Line for Tuesday, May 30th, 2006, written by Steven Russo, Planetarium Manager of the Suits-Bueche Planetarium at the Schenectady Museum.

Sunrise today was at 5:21 AM, and it set tonight at 8:24 PM. Sunrise tomorrow will be at 5:20 AM and Sunset will be at 8:25 PM.

The Moon is in a waxing crescent phase today, with the First Quarter on Saturday. It rose at 8:30 this morning, and will set around midnight tonight. Tomorrow it will rise at 9:07 AM, and will set shortly after midnight.

Watch the eastward motion of the Moon in the sky this week. Tonight, the Moon will be in between Castor and Pollux, the Gemini twins, and the planet Mars. On Wednesday, it will be very near the planet Saturn. On Friday, the Moon will be near the star Regulus, in the constellation of Leo.

The Sun sets tonight at 8:25 PM. The waxing crescent moon, in the constellation Cancer, sets tomorrow morning at 12:36 AM. Look for the moon less than three degrees above Saturn around 10:00 PM tonight. Mars will be in Gemini, less than nine degrees below and to the right of Saturn. Meanwhile, Jupiter shines prominently at almost negative two and a half magnitude in the constellation Libra. Jupiter will be easily seen in the south east at sunset, and will be on the meridian just before 11:00 PM.

At 10:00 PM tonight Leo is already well past the meridian in the west. High overhead is Ursa Major. Using the handle of the Big Dipper we find, first, zero magnitude Arcturus in the constellation Bootes, and then first magnitude Spica, in the constellation Virgo.

Arcturus is the fourth brightest star in the sky, an orange giant whose color is discernable to the naked eye, though more obvious with binoculars or a small telescope. In contrast, Spica is a blue white star much more distant than Arcturus, 280 light years away compared to Arcturus’ distance of 36 light years.

In the east, the constellation Hercules is already high up, followed by the constellations Lyra and Cygnus. Although Hercules is not at all prominent, it’s central feature, known as the keystone because its four stars form the shape of the topmost stone in an arch, is readily found. From there, it is a simple matter to trace the entire constellation. Hercules is probably best known for containing a magnificent globular cluster, M 13, which can be found along the western side of the keystone, about one third of the way from the top.

Moving toward the east, Lyra is unmistakable due to its most prominent star, zero magnitude Vega, a brilliant blue-white star, which is the fifth brightest star in the sky. Also visible under dark skies is a parallelogram of four stars below and to the left of Vega.

Lyra contains two sights with which most amateur astronomers are familiar. Between the two stars at the bottom of the parallelogram, beta and gamma Lyrae, can be found the famous Ring Nebula, a ninth magnitude planetary nebula with an angular size in the sky larger than the planet Jupiter. The term planetary nebula is a rather poor choice, as such nebula have nothing to do with planets, other than the most tenuous of resemblances. Planetary nebulae are formed by the casting off of the outer shell of a star’s atmosphere.

Also notable in Lyra is the famous quadruple star system of epsilon Lyrae, commonly known as the Double Double. A double star is easily seen in binoculars, or even by keen sighted people without optical aid, but a telescope is needed to see that each of these stars is, also, double. Look for epsilon Lyrae close to Vega, above and to its left.