Skywatch line for Wed. and Thur. August 27 and 28, 2008:
by Ray Bogucki

The famous "summer triangle" shines high overhead now at nightfall. The three stars that form the triangle are Vega in Lyra, the Lyre, Altair in Aquila, the Eagle, and Deneb in Cygnus, the Swan. Cygnus is characterized by the well-known Northern Cross and is usually depicted with the Swan flying south along the Milky Way. The Eagle is shown flying north along the Milky Way, while the Lyre, envisioned in the neat parallelogram just below Vega, sits at the edge of the Milky Way. All of these constellations contain many bright stars and are easily identified. In the next Skywatch line we will examine some of the fascinating objects in these three constellations, but for the next two weeks, the sky will be dark and moonless, presenting us with the opportunity to find three smaller and dimmer, but no less interesting constellations sandwiched between the Swan and the Eagle.

The first is Sagitta the Arrow, a collection of 4, fourth magnitude stars in the shape of an arrow about 10 degrees north of Altair. Though inconspicuous, this tiny constellation contains the Messier object M71, a globular cluster of stars, containing tens or hundreds of thousands of stars, visible in a small telescope.

Second is Delphinus, the Dolphin, a pretty collection of six or seven stars, mostly fourth and fifth magnitude, which were seen by ancient stargazers as a dolphin leaping out of the water, about 10 degrees northwest of Altair. They are similar to the Pleiades in Taurus the Bull, but not so tightly clustered. Once you find this credibly-named group of stars, you will always recognize it.

Third, and most difficult to find, is Vulpecula the Fox, which lies between Sagitta and Aquila. Even its brightest stars can only be seen by eye on a very dark night with exceptionally clear air. It does, however, harbor one telescopic gem, the bright "Dumbbell" nebula. This well named nebula, also known as "the apple core", which carries the Messier number M27, is what remains of a nova that appeared perhaps 48,000 years ago. A nova is an unstable star that suddenly becomes very bright for a short time when it explodes and blows part of its surface material into the surrounding void. This creates an expanding bubble of gas, lit by the remaining core of the exploded star.

Finally, in the moonless sky for the next two weeks, early risers can look for the appearance of a phenomenon known as the Zodiacal light. At this time of year, the ecliptic rises from the eastern horizon at a steep angle, leaning to the right between the bright star, Procyon, and the stars, Castor and Pollux, the Gemini twins. Along the ecliptic, a glowing triangle of light, about as bright as the Milky Way appears before any hint of the coming morning twilight begins to brighten the sky. This is sunlight reflecting from the countless particles of dust, generated by asteroids colliding in the asteroid belt, which fill the inner Solar System as they slowly spiral down before falling into the Sun. It should be visible in a dark sky between about 4 and 5 a.m. EDT.

This is the Skywatch Line for Monday and Tuesday, August 25th and 26th.
by Joe Slomka

The Sun sets at 7:40 PM, with night falling at 9:23. Dawn breaks at 4:30 AM, ending with sunrise at 6:14.

As the sky darkens, the planetary group we have been observing in western skies is now breaking up. Saturn is now lost in the Sun's glare. Venus and Mercury are bright enough to overcome twilight, but low enough to be hidden by trees or buildings. These inner planets lie within one and a half degrees of each other. Mars floats about ten degrees to Venus' upper left, but is so dim and small that it becomes a challenge object. All these planets set by 9 PM.

Jupiter remains the only easily visible planet. It glows high in the South at Sunset and remains up until 2 AM. While binoculars show the planet and four moons, those with moderately powered telescopes can watch the moon Europa and its shadow cross the giant planet's face. This begins at 8:15 PM and continues until Jupiter sets.

Morning finds the waning Moon in Gemini; Tuesday it is near Castor's leg, Wednesday near the star Pollux. Sunrise finds the Moon the shining in the East, above the bright star Sirius - the Dog Star.

As appropriate for the racing season, two horses appear by nightfall. The largest horse is Pegasus. The smallest is Equuleus. This dim constellation is easy to find. Pegasus flies upside down and is easily identified as a Great Square. Two thin star chains flow northward from the upper left. If one sweeps across the chain, binoculars disclose a large hazy oval; this is revealed, in telescopes, to be the Andromeda Galaxy – about two and a half million light years distant. You can see it with the naked eye under rural skies. Pegasus’ neck extends from the lower right corner and angles up. Equuleus is the small angular line of stars West of the Pegasus’ nose. A globular star cluster, M 15, lies exactly halfway between Pegasus’ nose and Equuleus. This too is easily seen in binoculars

Clear Skies
Joe Slomka

This is Dudley Observatory's Skywatch Line for Friday, August 22, through Sunday, August 24, written by Alan French.

On Friday night SPAC will host “The Planets Night” featuring a variety of astronomical activities. The Philadelphia Orchestra is performing Holst's “The Planets” at 8:00 PM. Dudley Observatory and The Schenectady Museum & Planetarium will have activities and handouts before the performance and during intermission. Dudley Observatory's Rising Star Interns will provide telescopes for viewing the night sky during intermission and after the program. Visit www.dudleyobservatory.org <http://www.dudleyobservatory.org/> or www.spac.org <http://www.spac.org/> for more details. Lawn seats are priced at $18.

Weather permitting, the Albany Area Amateur Astronomers will hold a public star party at 9:00 PM on Saturday night, August 23, at George Landis Arboretum in Esperance. At the star party a variety of telescopes will be set up to provide guests with views of Jupiter, colorful double stars, star clusters, nebulae, and galaxies. Anyone is welcome and there is no admission charge. The star party will be canceled if the skies are mostly cloudy. If the weather is questionable, call me at 374-8460 after 6:00 PM to verify the star party is being held.

To reach Landis Arboretum traveling west on Route 20, turn right just after crossing the Schoharie Creek as you enter Esperance. There is a large, green sign for George Landis Arboretum at the intersection. Follow the signs for about 1.5 miles until you reach the arboretum. You will see a farmhouse and barn on your right and a parking area on your left. Continue up Lape Road to the top of the short, steeper hill, and then turn right into the Meeting House driveway.

Be sure to dress warmly for either event. It has turned cool and it is easy to get chilled standing under the night sky.

This is the Skywatch Line for Monday and Tuesday, August Eighteenth and Nineteenth.
by Joe Slomka

The Sun sets at 7:52 PM, with night falling at 9:38, Dawn breaks at 4:18 AM and ends with sunrise at 6:05.

Last week's dance of planets continues. Venus is the brightest; Mercury lies one degree below Venus, while Saturn is so close to the horizon that it might be lost in the Sun's glare. The Venus-Mercury-Saturn trio forms a tight group six degrees in diameter, very low in the West. Mars is higher and well above Venus. Note the planets' positions over the coming week; they switch positions.

Having passed its "full" phase, the waning seventeen-day-old Moon rises in constellation Pisces. The Moon's southern position effectively blocks out the dim planets Uranus and Neptune, as well as distant galaxies.

Jupiter is the only object to withstand this luminous onslaught. It glows brightly next to teapot-shaped Sagittarius. Binoculars show the motions of its four Galilean moons. Moderate to high power telescopes permit views of Jupiter's weather systems, as well as moons crossing the planet's face.

Some images in the night sky duplicate constellations. For example, Bears. We have Ursa Major and Ursa Minor, the Great and Little Bears. There are two horses in the night sky: Pegasus and Equuleus. So also there are two Centaurs in the sky: Sagittarius and Centaurus. Sagittarius has ancient roots. The Mesopotamians portrayed a man-horse as early as 4200 years ago. Ancient Greece adopted the image and gave it unique powers. However, it is uncertain when the hybrid figure became an archer - the translation of the word "Sagittarius." Sagittarius is low in the southwest at nightfall; Centaurus is visible from Florida or similar latitudes.

The Albany Area Amateur Astronomers hold their monthly meeting this Tuesday, August 19 at 7:30 PM. It is the club’s custom to hold the August meeting at the George Landis Arboretum. Club members present a series of short talks in the Meeting House. Weather permitting, an observing session follows. This is an ideal time to see amateur astronomers and their telescopes in action. Directions can be found on the Albany Area Amateur Astronomers website. All club events are free to the public.

Clear Skies
Joe Slomka

This is the Skywatch Line for Monday and Tuesday, August Eleventh and Twelfth.
by Joe Slomka

The Sun sets at 8 PM; night falls at 9:52. Dawn breaks at 4:07 AM, ending with sunrise at 5:58.

All five bright planets are visible shortly after sunset. Venus is the brightest of four planets hovering low in the southwest. It appears as a very bright star. Mercury, next brightest, appears five degrees lower to Venus' right. Saturn shines two degrees to Venus's left. Mars is the smallest and dimmest; it lingers sixteen degrees to Saturn's left. These planets are quite low and require an unobstructed horizon. This week, these planets switch positions. Binoculars assist in tracking their progress.

The Moon lies due south at sunset and inhabits the constellation Sagittarius. Bright Jupiter, also in Sagittarius, is well up and sets before daybreak. Unfortunately, the waxing Moon spoils the view for tonight's main event.

Midnight finds the constellation Perseus rising from the northeast and hosting the annual Perseid meteor shower. Meteors are bits of comets or asteroids that encounter Earth and burn up in our atmosphere. When Earth runs into Swift-Tuttle’s path, meteor shower is the result. The Moon doesn't set until 1 AM Tuesday, and 2 AM Wednesday. Weather permitting, the best time to observe is after moonset. Simply take a lawn chair into a field and enjoy. A blanket helps to ward off the evening chill. You will see bright meteors streaking across the sky. If you backtrack their path, they seem to originate from Perseus. If weather does not permit observing on Monday night, the shower is still visible Tuesday night.

Another significant event occurs tomorrow. The bright star Sirius rises before the Sun. This occurrence took place in ancient Egypt before the annual Nile floods, which fertilized farm fields. Sirius is called the “Dog Star,” because it is the brightest star in the constellation Canis Major, the Large Dog. The moniker “Dog Star” goes back to ancient Mesopotamian cultures. The “Dog Star” also gives rise to the “Dog Days of Summer.” Ancients thought that the brilliant star added to the summer heat. Sirius is twenty-three times brighter than our Sun, but, at 8.6 light years distant, adds no additional heat.

Clear Skies
Joe Slomka

This is Dudley Observatory's Skywatch Line for Friday, August 8, through Sunday, August 10, written by Alan French.

The Moon is at first quarter late Friday afternoon, so a waxing gibbous Moon will dominate the night skies during the evening hours over the weekend. The Moon will set at 11:16 PM on Friday night, 11:50 on Saturday night, and one-half hour after midnight on Sunday.

The well known annual Perseid meteor shower peaks on the evening of Monday, August 11, into the early morning hours of Tuesday, August 12. Over the weekend, you should see some early members of the Perseids gracing the skies after 1 AM. More meteors are seen after midnight – which is actually 1 AM due to daylight savings time – because we are then on the front side of the Earth as it moves through space. You see the same effect driving through a snowstorm, with more snow hitting the front of your car than hits the rear.

The Moon will set at 1:21 AM on Tuesday morning, so if you set your alarm to get up then when you retire Monday night you'll have some good viewing hours for the Perseids. Some are predicting a modest increase in the number of meteors between 1 AM and 3 AM, but the more traditional peak hours start as sunrise approaches.

Meteors can appear anywhere in the sky, so just look where you have the best view. A reclining lawn chair is ideal for meteor watching. Make sure you dress warmly, or bring some blankets. August nights can be surprisingly cold. Bug repellent is also an excellent idea.

If you trace their paths across the sky, meteors from the Perseid shower will all point to the constellation Perseus. There are a couple of other minor showers in progress, so you may also see some Delta Aquarids and Kappa Cygnids. You may also catch a few sporadics – meteors that are not associated with any known shower.

While the numbers of meteors will be less over the weekend than they will be early Tuesday morning, the capricious weather makes it wise to take advantage of any clear morning skies if you wish to enjoy some of the fine Perseid meteor shower this year.

Skywatch Line for Wed. and Thurs., August 6 & 7, 2008:
by Ray Bogucki

This week and next promise to be a great period for planet watchers who have an observing site with an unobstructed view of the western horizon. Currently four of the five bright planets can be seen shortly after sunset. Jupiter is well up in the southeast, blazing at a magnitude of negative 2.6. Venus, Saturn and Mars are strung out, in the order given, in a short line nearly due west and close to the horizon. Venus is the lowest, while Saturn and Mars are slightly above and to the left of Venus. Because all three of these planets set within about an hour after sunset, begin looking for them in the bright twilight about 20 minutes after sunset. Locating them will be a real challenge and binoculars will be a great help in finding them in the bright sky.

Venus passed behind the Sun at superior conjunction last June and is now appearing as an evening star. Because of its high orbital velocity, Venus is climbing rapidly away from the Sun and gaining on Saturn. All through next week the planets will perform an intricate ballet, choreographed by their differing orbital velocities and distances from the Sun. By next Wednesday, August 13, Venus will be passing Saturn at its closest approach, about one Moon-width. Notice that Mercury, the innermost and fastest moving planet, has also emerged from behind the Sun, and at this time appears just below the Saturn-Venus duo, making all five bright planets visible at one time. By Friday, fast moving Mercury will be passing Saturn and moving on to catch up with Venus. It will pass Venus the following week and the two (Mercury and Venus) will continue moving eastward to gang up on Mars. They will then repeat their choreography with Mars during much of September.

Closer to us, the Earth is beginning to pass through the debris left in our orbit by comet Swift-Tuttle to produce the Perseid meteor shower. A group of astronomers, gathered to observe some star clusters last Friday, August 2, were delighted to see at least six bright Perseid meteors within an hour. The peak of the shower is not expected to occur until next Tuesday morning, August 12, but watch for meteors anytime you are out until near the end of August. The best show should come on Tuesday morning in the dark window between moonset, about 2 a.m., and the beginning of morning twilight, about 4:30 a.m. A quick calculation produces the interesting result that, at an orbital velocity of 1.6 million miles per day, the Earth will cover about 40 million miles along its orbit in the approximately 25 days that the Perseid meteors are visible. That means that the debris stream from comet Swift-Tuttle is at least an amazing 40 million miles wide. We will examine some fascinating aspects of this comet in next week's Skywatch line.

This is the Skywatch Line for Monday and Tuesday, August Fourth and Fifth.
by Joe Slomka

The Sun sets at 8:10 PM; night falls at 10:06 PM. Dawn breaks at 3:55 AM, ending with sunrise at 5:51.

A half hour after sunset, the Moon and three planets bunch low in the West. Venus is brightest, and lowest. Venus resembles a very bright star or airplane landing lights. Regulus, the brightest star in Leo, may appear dimmer beside Venus. Saturn appears higher to Venus' left. Mars lies to Saturn's upper left; Mars is very small and dim and struggles to overcome the twilight. The Moon appears as a bright, thin crescent at the tail end of this group. Trees and hills easily hide this alignment. If the western horizon is clear, binoculars may help. All set by 10 PM.

Jupiter is up by sunset and lies due south at 11 PM. While binoculars show the motions of Jupiter's Galilean moons, observers with moderately powered telescopes have a treat tonight. The moons Ganymede and Callisto cross the planet's face. Ganymede's shadow also appears as a small black dot crossing the giant planet. These events begin shortly before sunset and end shortly after 1 AM. Jupiter sets at 3:32 AM.

Midnight finds Uranus and Neptune ideally situated for observation. While hunting for these planets, you may encounter meteors in their neighborhood. These are the annual Aquarid meteor showers. Meteors are pebble-sized pieces of comets and asteroids. When the Earth's orbit crosses a debris stream, a meteor shower results. Next week, the annual Perseid meteor shower takes place. Perseids are brighter and popular; but this year, a bright Moon interferes with the Perseids. The Aquarids are sparser but free of lunar interference.

Professional astronomers study narrow fields: star evolution, black holes, galaxy formation, cosmic rays, etc. However, amateurs still contribute Science. Amateurs scan the skies, looking for something new. They discover comets, supernovae, and brightening stars, and report their finds for professional follow-up. Last weekend saw the annual Stellafane convention. Amateurs gathered to discuss telescope making techniques and latest discoveries. If you have the chance, attend an amateur astronomy convention. You will find a welcoming atmosphere, and a whole new universe.

Clear Skies
Joe Slomka