Early risers will be treated to an elegant gathering of bright objects before sunrise tomorrow (Thursday) morning. Venus and Mars, which are sticking close together all through this month, will be joined by the waning crescent Moon to form a picturesque triangle, with Mars directly below the Moon, and Venus just to the right of the other two, as the sky is beginning to brighten, at about 4:30 a.m. Use binoculars.

Somewhat closer to home, astronomers' attention this week has been riveted on the activities of the seven astronauts aboard the Space Shuttle Atlantis, who rocketed into orbit on Monday, May 11. Their mission is to make the fifth and final maintenance and repair visit to the Hubble Space Telescope (HST). The objectives of the mission include the installation of two new instruments, and the replacement of all six gyroscopes and all rechargeable batteries. In addition, the astronauts will attempt to repair the Advanced Camera for Surveys (ACS) and the Space Telescope Imaging Spectrograph (STIS). Because the latter two instruments were not designed for in-orbit repair, this task presents a daunting challenge. Adding to the risk is the fact that Hubble's 350-mile high orbit is filled with thousands of bits of space junk - large and small bits of old satellites and rockets. A strike by any of the debris particles would pose a serious threat to the HST and to the astronauts themselves.

Here is a short synopsis of what has been accomplished so far.

On the first space walk, on Thursday, two astronauts removed the old, wide field camera after a long struggle with a stuck bolt. The piano-sized camera was then replaced with a new one that covers a wider range of wavelengths -- from ultra violet to near infrared -- and has a greater sensitivity. They next replaced a computer data-handling device, which had failed last September.

On the second space walk on Friday, a second team replaced the six gyroscopes and some of the old batteries. Three of the old gyroscopes had died and two of the others were acting up leaving just one reliable unit to stabilize the telescope.

On the third space walk on Saturday, chief mechanic, John Grundsfeld, opened up and repaired the burnt out ACS. Initial tests done at Mission Control showed that the camera was working again.

On Sunday, after a struggle with another stuck bolt, the STIS, disabled by a power failure 5 years ago, was brought back to life when a new electronics power supply card was inserted.

On Monday, May 18, as this is being written, the astronauts were expected to replace some insulation on the HST and on Tuesday, the HST is scheduled to be released back into its own orbit, hopefully to continue sending improved data back to Earth for another 5 to 10 years.

This is the Skywatch Line for Monday and Tuesday, May 18th and 19th.
by Joe Slomka

The Sun sets at 8:15 and ends with night falling at 10:17 PM. Dawn breaks at 3:27 AM and ends with the Sun rising at 5:29.

Mercury, which has been in the evening sky for the past few weeks, reaches inferior conjunction on Monday; this means that Mercury passes between Earth and the Sun and will soon become seen in pre-dawn skies.

Saturn remains the only planet visible in evening skies, creeping eastward beneath Leo, the Lion. While the famous rings are virtually invisible, some of the planet's many moons are visible, depending on the size of your observing instrument. High-powered binoculars will show Saturn as a very small object. Small telescopes permit views of Saturn and its largest satellite - Titan. Medium sized instruments should have Dione and Titan on opposite sides for Monday night; Tuesday night's views should include Dione, Rhea and Titan on the same side of Saturn. All three moons are tiny even in the largest telescopes. Titan shines like a small star, while the others are fainter. All the visible moons are in line with the rings and help distinguish background stars from true Saturnian moons. The rest of Saturn's sixty-one satellites are detailed to keeping the ring system intact and can only be detected by professional observatories or spacecraft.

Jupiter and Neptune rise in Capricornus just as Saturn prepares to set. Neptune shares the same binocular and finder views as Jupiter. Jupiter provides an example of a star pretending to be a moon. On Wednesday morning, the star Mu Capricorni appears to be a Jovian satellite. It is easy to penetrate this fraud. Mu is not in line with the rest of the Moons.

Earth's Moon rises in pre-dawn hours amid the stars of Pisces. Jupiter, Neptune, Uranus, Venus and Mars form a ragged line from East to Southeast. Dim Mars lies six degrees to brilliant Venus' left. Likewise, Uranus lies fifteen degrees to Tuesday's Moon's right. Wednesday finds Uranus ten and a half degrees to the Moon's right.

Clear Skies
Joe Slomka

This is Dudley Observatory's Skywatch Line for Friday, May 15, through Sunday, May 17.
by Alan French

The space shuttle Atlantis is now on an 11 day mission to the Hubble Space Telescope. This ambitious mission will refurbish the Hubble space telescope, increasing its abilities, and extending its working life through at least 2014. Originally, NASA had decided not to send a shuttle to the space telescope, but then agreed to one final mission.

The orbit of the Hubble Space Telescope rarely brings it far enough north to be visible from our area, and we have no chances to see it while the telescope is secured in the shuttle's payload bay for servicing. Our next opportunities to see the space telescope will be in mid-June, when it will only appear a little over 10 degrees above our southern horizon.

On Sunday morning the last quarter Moon will be very close to Jupiter. Look for the lovely duo in the southeastern sky around 4:00 AM.

The Big Dipper is high in the north as the sky darkens. The Dipper is not actually a constellation – it is an asterism, an obvious pattern of bright stars. Most people are familiar with the four stars that make up the bowl, and three stars that make up the dipper's handle. When it is high it the sky the dipper is upside down, and the handle stretches eastward.

All the stars in the Big Dipper are in the constellation Ursa Majoris, the Great Bear, but it includes many more stars. The four stars of the dipper make up the back end of the bear, and the three stars of the handle mark his unusually long tail. If you look you should see two more stars in front of the bowl which outline the front of the bear, and one more star farther out from these that marks his nose. One of his front legs and both of his rear legs can also be traced among the stars.

The Albany Area Amateur Astronomers will meet at 7:30 PM on Tuesday night at the Schenectady Museum. Club member Greg Nowell will present “Tips and Tricks of Equatorial Mounts.” All meetings are open to all and free of charge.

Next weekend, May 22 and 23, the amateur astronomers will host public star parties at Landis Arboretum in Esperance, beginning at 9:30 PM. Club members will provide guests with views of celestial showpieces, including Saturn, through a variety of telescopes. Star parties are canceled if the skies are mostly cloudy.

SKYWATCH LINE FOR WED. & THURS., MAY 13 & 14, 2009:
by Ray Bogucki

This week offers some interesting planetary events. Mercury is currently out of sight near the Sun as it prepares to pass between Earth and the Sun at inferior conjunction next Monday. Of the remaining 4 bright planets, Saturn alone dominates the evening sky. Well up, but not very high in the southern sky, Saturn shines a little brighter than a first magnitude star, with a steady yellow-white light, below the Sickle asterism in Leo. Throughout the summer, watch Saturn's rings become ever thinner as the plane of the rings inclines ever closer to our line of sight.

The other 3 bright planets are all found in the eastern sky before sunrise. Venus and Mars will remain close together through the month of May, rising about 4 a.m. in the east, just as the first hints of morning twilight begin to brighten the sky. Mars shines with the respectable magnitude of one, but it might be hard to find in the twilit sky near the horizon. The brilliance of Venus, on the other hand, is unmistakable, and once you find Venus, just lower your eyes or binoculars a few degrees below and to the left. You will find Mars trailing Venus all month like a faithful dog trailing its mistress.

Finally, the giant Jupiter, rising about 2 a.m. in the southeast, will be well up, in good viewing position in the south by the beginning of twilight. Observers with telescopes can witness a double shadow transit on Jupiter early Sunday morning, May 17. Shortly after midnight Saturday, the shadow of Callisto, the outermost Galilean moon, will appear on the surface of Jupiter. When Jupiter rises here about 2 a.m., Callisto's shadow will already be part way across Jupiter's face. About 4 a.m., the shadow of the innermost moon, Io, will also enter Jupiter's surface, and because Io moves much faster, its shadow will begin chasing Callisto's shadow across the surface. Callisto wins the race when its shadow leaves Jupiter's surface at 5:24 a.m., almost an hour before Io's shadow leaves. These little dark spots on Jupiter are easily seen in a modest backyard telescope.

Tomorrow morning (Thursday), Jupiter will also act as a guide for finding our outermost normal planet, Neptune, which is not visible to the unaided eye. This distant ice giant will appear less than one degree directly to the left of Jupiter as a softly glowing, blue-green dot, easily distinguished from the pinpoint brightness of a star.

This is the Skywatch Line for Monday and Tuesday, May eleventh and twelfth.
by Joe Slomka/p>

The Sun sets at 8:08 PM, with night falling at 10:05. Dawn breaks at 3:38 AM, ending with sunrise at 5:35.

As the Sun sets, planet Saturn is easily found beneath Leo and continues its westward creep. Its famous rings open up slightly this month, and then close at month's end.

Mercury lies about seven degrees above the western horizon and sets about 9 PM. This planet may be difficult to find amid the still bright sky.

The waning Moon, about ninety percent "full," hovers around the teapot-shaped constellation Sagittarius on Monday and Tuesday nights. Its glare blinds us to dim, distant objects such as galaxies.

Jupiter and Neptune rise about ninety minutes before Dawn. Despite the nearby Moon, they should be easy to spot near the eastern end of the constellation Capricornus. Jupiter is very bright. Neptune lies about one degree to Jupiter's right, within the same binocular or finder scope field. Saturn sets about an hour after Jupiter rises; if horizons are clear, it is possible to see the two largest planets at opposite ends of the sky.

Between Dawn and Sunrise, three additional planets rise. Venus is brightest and acts as a guide to Mars and Uranus. Venus shines five and a half magnitudes, or 160 times, brighter than Mars. Mars lies about six degrees to Venus' lower left - again just within a binocular field. Venus appears about six times larger than Mars, which looks like a mere red speck. Uranus lies in Pisces, thirteen degrees to Venus' upper right. Uranus may be difficult to find, but becomes easier as the month progresses. Five of our Solar System's planets are visible prior to sunrise.

Like its fellow outer planets: Jupiter and Uranus, Neptune is a gas giant - a large ball of gas. It is seventeen times heavier and thirty times further than Earth. Neptune takes almost 164 years to circle the Sun. Neptune sports a faint ring system, visible only to space telescopes. It is warmer at its equator and poles than its middle. It has a chaotic weather system that permits storms to switch latitudes.

Clear Skies
Joe Slomka

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

The Moon is Full Friday evening so the weekend nights will be dominated by bright moonlight. On Friday, the nearly Full Moon rises a little north of southeast just as the Sun sets at 8:03. Moonrise on Saturday night is at 9:09 PM, and it will rise at 10:09 PM on Sunday night.

The Full Moon of May was the Milk Moon to the English and the Flower Moon to Native Americans. It is also called the Corn Moon and the Hare's Moon.

There is a superb pass of the International Space Station or ISS over the Capital District on Mother's Day. We see satellites because they are still up in sunlight while we are down in the Earth's shadow. Because the ISS is very large and has a lot of area to reflect sunlight it is the brightest orbiting satellite, and appears brighter than the brightest stars. Sometimes a satellite will move into the Earth's shadow while it is passing though our skies, and fade from view before our eyes. On Sunday night the ISS will pass almost directly overhead, and move into the Earth's shadow as it approaches the northeastern horizon.

Our times for the ISS will be given in hours, minutes, and seconds. They are for Schenectady, but should be close enough for anyone in the Capital District and surrounding areas. On Sunday the ISS will first appear coming up from the west southwestern horizon at 9:57:21 PM. It will be highest at 10:00:16 when it will be 82 degrees above the northwestern horizon – essentially appearing to pass directly overhead. As it approaches the northeastern horizon just before 10:02, and is 24 degrees above the horizon, it will begin moving into the Earth's shadow and fading from view. How long can you follow it before it vanishes completely?

If you live in Schenectady or directly north or south of the city you may be able to catch an Iridium flare eight minutes after the ISS vanishes. The Iridiums are a large number of satellites for phone service. They have a highly reflective antenna that catches sunlight and reflects it down to Earth very intensely. If you are in the right place and the sunlight is reflected down to your eyes, the Iridium will brighten for a few seconds and exceed the brightness of Venus at its best.

If you are in the right area to see the Iridium, note the bright star Vega, fairly low in the northeast and very close to where the ISS vanishes. The Iridium flare will occur to the upper right of Vega, and it will be brightest at 10:10:08 PM on Sunday night. Make sure to set your watch, and start looking a minute or so earlier. The Iridium will first appear as a faint satellite moving from north to south. If you are looking in the right general area it should be easy to spot as it starts to flare.

Predictions for Iridium flares for you location can be found at www.heavens-above.com <http://www.heavens-above.com/>. Be sure to set up your location from their database or map before getting the predictions.

Skywatch line for Wed. and Thuirs., May 6 & 7, 2009:
by Ray Bogucki

The Earth, in its orbit, is now a little more than halfway between the Spring Equinox, when it crosses the celestial equator heading north, and the Summer Solstice, when it reaches the northernmost point in its path through the sky. Each day the Sun breaks the horizon at sunrise and sunset a little farther north than the previous day. This behavior lengthens the amount of sunlight by 2 or 3 minutes each day, as well as making the Sun's position at the southern meridian at noon about a half Sun-width higher.

These phenomena are generally well known, but what is less well known and less obvious, is the fact that the Earth is also moving farther away from the Sun at a rate of about 1,000 miles each hour, and is slowing a little in its orbital speed. This behavior is dictated by the elliptical shape of the Earth's orbit. After Copernicus, in 1543, proposed that the Earth and the other planets revolve in orbits around the Sun, astronomers who accepted his proposal assumed that the orbits of the Earth and the other planets around the Sun were perfectly circular. However, in 1609, the same year that Galileo began using his telescope to study the motion of the four large moons around Jupiter, Johannes Kepler published his treatise, "The New Astronomy", in which his "first law" proposed that orbiting bodies travel around their larger companions not in circular, but in elliptical orbits. His "second law" states, in effect, that the orbiting bodies (e.g., the planets) move more slowly in orbit when they are farther from the larger companion (e.g., the Sun). Kepler's theses were based on a lifetime of precise measurements of the exact positions of the planets in the sky, night after night.

A circle has one focus at the precise center of the circle, while the oval-shaped ellipse has two centers of focus along its major or longer axis. In the Earth-Sun system, the Sun occupies one of the focuses, while the second focus remains empty. Thus Kepler's second law predicts that the Earth's orbital speed should now be slowing down a bit as it approaches aphelion, its farthest distance from the Sun on July 4. On that date the Earth will be 3.1 million miles farther from the Sun than it was at perihelion, its closest approach to the Sun on January 4. To prove Kepler's laws for yourself, count the number of calendar days between the vernal equinox on March 20, and the autumnal equinox on September 22, during which period the Earth is at a greater distance than its average distance from the Sun. Then compare that number with the number of days between the autumnal and vernal equinoxes. One might assume intuitively that the two equinoxes divide the year into two equal halves, but the numbers tell a different story.

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

. The Sun sets at 8 PM, with night falling at 9:53. Dawn begins at 3:52 and ends with sunrise at 5:45.

As the Sun sets, the Moon and two planets become visible. Monday's Moon is eleven days old and 83 percent illuminated; it stands to Saturn's left in Leo. Tuesday's Moon lies next to Virgo. Both days find the Moon setting just before Dawn.

Saturn continues its creep westward beneath Leo. Its rings and moons are visible, but degraded by the Moon's glare so close by.

As the sky darkens, Mercury appears as a tiny planet to the left of a dipper-shaped star group - the Pleiades. This is a binocular sight not to be missed, low in the West. Both set around 9:30 PM. Mercury fades rapidly and disappears into the Sun's glare by midmonth.

Nightfall finds the Moon and Saturn up for most of the night. By midnight, most of the summer constellations: Hercules, Lyra, Ophiuchus, Libra, Aquarius and Scorpius are up and visible. Between Midnight and Dawn Tuesday and Wednesday, an observer may see more then the usual number of meteors streaking from the eastern horizon. The annual Eta Aquarid meteor shower takes place. Like most meteor showers, this one is the progeny of a comet. About every 76 years, Comet Halley appears in our skies. The Eta Aquarid meteors are the litter left behind. However, the Moon's luminosity reduces the number visible to only the most brilliant meteors.

Dawn sees Jupiter and Neptune rise with the constellation Capricornus. Jupiter is brighter and larger; Neptune appears smaller and blue. Both fit within the same binocular view.

The hours before sunrise find Venus, Mars and Uranus joining Jupiter and Neptune. A binocular user sees bright Venus six degrees above smaller Mars. The telescopic observer sees Venus as a large ball about a third illuminated. Mars is just a small red ball, even under high powers.

Clear Skies
Joe Slomka

This is Dudley Observatory's Skywatch Line for Friday, May 1, through Sunday, May 3, written by Alan French.

The Moon was at first quarter late Friday afternoon so a waxing gibbous Moon will dominate the evening sky over the weekend. At 9:00 PM on Friday you'll find the Moon in the southwestern sky. By Saturday it will be farther east and just below Regulus, the brightest star in Leo, the Lion. On Sunday night the Moon will be directly below Leo, with Saturn to the upper left of the Moon.

The early evening hours this weekend would be ideal for exploring the lunar landscape by telescope or binocular. Even binoculars will reveal the larger craters and mountains, and any spotting scope or astronomical telescope will reveal a marvelous lunar landscape. The details are best seen along the terminator, the line that marks the border between the bright sunlit Moon and the portion still in lunar night. Between New and Full Moon this is the sunrise line. Here the shadows are longest and the small features stand out in bold relief. Look for mountain peaks and crater walls just over into darkness where they are catching the light of the rising Sun. Then watch as the rising Sun's light slowly reveals more of the mountain or crater. Although the Moon itself is unchanging, it is fascinating to watch the rising Sun bring a crater or mountain range into full view.

Saturday, May 2, is National Astronomy Day, and it will be celebrated at several venues in the Capital District. From Noon until 4 PM members of the Albany Area Amateur Astronomers, and representatives and Rising Star Interns from Dudley Observatory will be at the Albany Heritage Area Visitors Center at 25 Quackenbush Square. Weather permitting, special telescopes will provide safe views of the Sun, and amateur astronomers will be on hand to answer your questions about the night sky and telescopes.

From 8:30 until 10:00 PM on Saturday night the Pine Bush Discovery Center at 195 Karner Road will host a star party featuring views of the Moon and Saturn. Members of the Albany Area Amateur Astronomers and Dudley Observatory's Rising Star Interns will provide telescopes for your viewing enjoyment. The star party will be canceled if the skies are mostly cloudy, and there is a modest admission charge - $2 per person of $5 per family. Call the center at 456-0655 for details or, if the weather seems questionable, to verify that the event is being held.

On Saturday night open houses will be held at Union College's observatory and RPI's Hirsch Observatory. Weather permitting, the observatory at Union College, located on top of the Olin Center, will be open from 8:30 until 10:00 PM. Hirsch Observatory will be open from 8:00 until 10:00 PM, and there will be an alternate program if the cloudy skies preclude observing.