Skywatch April 2009
(newest at top)

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.

Skywatch line for Wed. and Thurs., April 29 and 30, 2009:
by Ray Bogucki

On Thursday evening, as the sky darkens, search about 4 Moon-widths above the First Quarter moon for the excellent open star cluster M44, usually known as the "Beehive". This cluster had been known since antiquity as a faint, fuzzy patch of light, but 400 years ago, Galileo turned his new telescope to the fuzzy patch and declared that it was actually a cluster of stars. Binoculars or a small telescope reveal a cluster of about 50 stars, all born at about the same time, 660 million years ago, and 580 light-years away.

On the evening of Tuesday, May 5, and into the next morning, the Earth will be passing through the densest part of the cometary debris of Halley's Comet, probably the best known of all comets. The collision of these particles with the molecules and atoms in the earth's atmosphere gives rise to the eta-Aquarid Meteor Shower. This is a very reliable shower because more debris is added every 76 years as Halley's Comet swings through the Earth's orbit. Observers in more southerly latitudes get to see more meteors than we do because the radiant point in Aquarius, from which all the Aquarid meteors appear to originate, rises earlier and reaches higher in the sky than it does here. Another difficulty arises this year because the Moon will be almost full and it will brighten the sky all night, washing out all but the brightest meteors.

Last week, NASA's Swift satellite, dedicated to detecting gamma-ray bursts (GRB) from distant reaches of the Universe, reported the most distant burst ever recorded. The process of recording these very short-lived events is carefully choreographed. The satellite, upon detecting a GRB, immediately transmits the exact location of the burst to large telescopes on the ground, which immediately swing their focus to that location. Because most GRBs last only a few seconds, the big telescopes miss the main event but they can often image a fading infrared afterglow. Careful spectroscopic analysis of the infrared light can yield the distance and nature of the event. It appears that last week's GRB was the result of a massive supernova star detonation, the light of which traveled for a staggering 13 billion years before reaching us, almost twice the distance of the previous record.

The implications of this observation are truly mind bending. Since the Earth was only formed about 4.5 billion years ago, we have just witnessed an event that occurred only about 500 million years after the Big Bang, and 8.5 billion years before the Earth even existed. This is a true time machine experience!

This is the Skywatch Line for Monday and Tuesday, April twenty-seventh and twenty-eighth.
by Joe Slomka

The Sun sets at 7:52 PM; night falls at 9:41. Dawn breaks at 4:04 AM and ends with sunrise at 5:55.

At sunset, the Moon and two planets attract our attention. The three-day-old Moon appears as a crescent, about ten percent illuminated. As the sky darkens, the Moon is seen to reside in the horns of Taurus, the Bull. Tomorrow night, the Moon appears at the feet of Gemini and two degrees from the M-35 galactic star cluster.

Mercury appears moderately high in the West near the Pleiades asterism. Asterisms are groups of stars that do not form a constellation, but are so unique that they become famous on their own. Indeed, the Pleiades look like a mini dipper in binoculars. The darkening sky should present a pretty picture of the Pleiades with tiny Mercury about two and a half degrees below.

Saturn remains up most of the night and glows below the Lion's belly. For the last few weeks, Saturn has been creeping westward; so, it does not appear at Leo's feet. This retrograde motion lasts until early May. Saturn's rings are slightly tilted toward Earth, permitting views of some of its 61 moons. An example takes place after 2:20 AM Wednesday morning. Saturn is about 19 degrees above the western horizon. A telescopic observer with high power eyepieces will see a shadow march across the face of Saturn. Titan is Saturn's and the Solar System's largest satellite, and the source of the shadow. Shadow transits are fairly common events for Jupiter observers; however, Saturn, being further away, presents fewer opportunities; the combination of Titan's size and Saturn's very bright cloud cover permits views of such events.

Morning skies show five planets clustered in the East. Jupiter and Neptune rise before daybreak, while Venus, Mars and Uranus rise in the hour before sunrise. Mars recently passed perihelion, closest to the Sun, last week. Martian summer begins for the southern hemisphere. These factors usually begin the season for major dust storms to appear on Mars. Usually such events are visible to telescope users, but Mars' rising so close to sunrise prevents observation for the time being.

Clear Skies
Joe Slomka

This is Dudley Observatory's Skywatch Line for Friday, April 24, through Sunday, April 26, written by Alan French.

The Moon is new late Friday night, so the skies will be dark and moonless, making this a perfect weekend for stargazing. The Albany Area Amateur Astronomers will take advantage of the dark weekend skies by holding star parties at Landis Arboretum in Esperance and at Grafton Lakes State Park.

At star parties club members will provide guests with views of celestial sights through a variety of telescopes. Saturn is well placed and telescopes will show its now nearly edge on rings and some of its brighter moons. Telescopes will also reveal nebulae, star clusters, and galaxies.

The star party in Grafton Lakes State Park will be held on Saturday night beginning at 8:00 PM. Look for the amateur astronomers and their telescopes in the main parking lot.

Star parties will be held at 9:00 PM both Friday and Saturday nights at Landis Arboretum. Entering Esperance from the east on Route 20, take a right at the large green Arboretum sign just after crossing the Schoharie Creek. Follow the signs for about 1.5 miles to Landis. When you see the farmhouse on your right and a parking area on your left, continue up Lape Road for about 50 yards until the steep hill begins to level out, and then take a right into the Meeting House field. A reflective sign will mark this turn.

The Landis star parties will include an introductory program at 9:15 in the Meeting House, followed by a brief tour of the constellations.

Star parties are canceled if the skies are mostly cloudy. Call 374-8460 for further information about the Landis star parties. For Grafton Lake star parties, call 658-3138.

On Sunday night at 8:50 PM a thin crescent Moon will be a lovely sight about the west northwestern horizon. If you view the thin crescent with binoculars, you'll find the Pleiades star cluster just below and right of the Moon. The bright star just below the Pleiades is the innermost planet, Mercury, now making its best appearance in the evening sky of 2009.

Skywatch line for Wed. and Thurs., April 22 and 23, 2009:
by Ray Bogucki

This morning (Wednesday) the Lyrid Meteor Shower was followed, in the early morning twilight, by the very close pairing of the waning crescent Moon and Venus. Observers who did not have the opportunity to witness this spectacle, will get another chance on Sunday evening (April 26) when the new, waxing crescent Moon will find itself low in the western sky, just above and to the left, or east, of the famous star cluster known as the Pleiades or the "Seven Sisters". Because the Moon's orbital travel around the Earth carries it about one Moon-width eastward each hour, it is apparent to the eye that the Moon must have passed close to the Pleiades late Sunday afternoon in the daylight, when the star cluster was not visible. To make the scene more interesting, the planet Mercury, now at its farthest distance from the Sun and shining with the bright magnitude of zero, is found a couple of degrees directly below the Pleiades. The close gathering of these three photogenic objects low in the west-northwest will present a memorable view in binoculars or a small, wide field telescope.

After this group has set, turn your attention to Saturn, which is currently well placed for observing, fairly high in the south in the constellation Leo, below the lion's hind quarters. During April, Saturn has favored viewers by tilting its rings a little more open to about 4 degrees to our line of sight. From May on, the angle will grow smaller until September 4th, when the rings will be precisely edge-on to our line of sight and the rings will disappear completely. Although the rings are over 120,000 miles in diameter, they are only a few hundred yards thick.

On the other hand, if you are out in the early morning, glance up at Jupiter which rises about three hours before the Sun and has reached a modest height in the southeast as morning twilight begins. Our line of sight to Jupiter is now very close to the giant planets' equatorial plane so that the four Galilean moons, which usually appear to skim a little above or below each other, will now be regularly occulting and eclipsing each other. About 5 a.m in the morning of Sunday, April 26, you may be surprised to find that Jupiter appears to have five moons! The imposter is a sixth-magnitude star, 44Capricorni, which, for a few hours, will coincidentally line up with the four real moons.

This is the Skywatch Line for Monday and Tuesday, April twentieth and twenty-first.
by Joe Slomka

The Sun sets at 7:44 PM and ends with nightfall at 9:29. Dawn breaks at 4:19 AM and ends with sunrise at 6:04.

Two planets grace the twilight sky. Mercury lies about seventeen degrees above the setting Sun. Though bright, its small size makes finding it difficult for the beginner. The best way to see Mercury is to point binoculars above where the Sun set, and slowly scan the sky. In time, a small bright star-like object glows amid the twilight. High-powered telescopes show Mercury about half illuminated. Tuesday night has Mercury setting at nightfall.

Saturn lies almost due south, beneath the hind feet of the constellation Leo, the Lion. Saturn is the brightest object in Leo and its off-white color makes it easy to spot. Ordinary binoculars show little; telescopes display its rings and some of its 61 moons.

First light sees Jupiter, Neptune and the Moon rising. Jupiter and Neptune adorn the western end of Capricornus. Tuesday has the Moon just rising. By the hour before sunrise, five planets rise from the east; Venus, Mars and Uranus join Jupiter and Neptune. Venus and Mars are separated by about three and a half degrees. Venus is far brighter than Mars, which is seen below Venus. Wednesday morning sees the Moon one degree from Venus; western parts of the U.S. see the Moon occult (eclipse) Venus.

Observers who stay up after midnight Tuesday night may see meteors streaking from the East. This is the annual Lyrid meteor shower. Like most meteor showers, the Lyrids are litter left over from passing comets; as these specs of dust enter our atmosphere, they burn up in a fiery trail. This meteor shower has been continuously observed for over 2600 years. The shower is linked to Comet Thatcher and appears to originate near the bright star Vega in the constellation Lyra. Typically, between ten and twenty meteors are seen per hour. However, there have been sporadic cases of the shower rate exceeding three hundred per hour. The most recent outburst occurred in 1982, with about ninety per hour.

Clear Skies
Joe Slomka

This is Dudley Observatory's Skywatch Line for Friday, April 17, through Sunday, April 19, written by Alan French.

Elusive Mercury is now making its best appearance of the year for our northern latitude, and can be found in the evening sky after sunset. The Sun sets at 7:40 PM and the best time to look for Mercury will be between 8:30 and 8:40. You'll need a clear, unobstructed view to the north northwest, and the sky near the horizon should be free of clouds and haze. Under these conditions Mercury should be easy to spot – it now shines at nearly magnitude -1. At 8:30 the innermost planet will be just over seven degrees above the north northwestern horizon. By 8:40 its height will be five and a half degrees. There are no other bright stars in that region of the sky. Although the planet will be lower at 8:40, it may be easier to spot against the darker twilight sky.

If you have trouble spotting Mercury, the well known Pleiades star cluster, known to many as the Seven Sisters, provides a convenient landmark. The Pleiades lie just under 20 degrees above the north northwestern horizon at 8:40, and Mercury lies 15 degrees below and a bit north or right of the cluster. If the skies are hazy, binoculars may aid the search.

When I was in school very little was known about Mercury. Its distance and closeness to the Sun make observations difficult. Planets are best observed when they are high in the night sky, but Mercury is never far enough from the Sun in our sky to be high in the dark night sky. Astronomers believed that Mercury was tidally locked, keeping one face always toward the Sun. The Sun's tides have locked Mercury into a very slow spin, but it does not keep one face toward the Sun. Relative to the stars, it rotates once every 59 days. Combined with its 88 day orbital period, this makes a Mercurian day – from sunrise to sunrise, 176 Earth-days long.

Mercury will be highest in the evening sky on April 25.

On Sunday morning early risers will have a chance to see a close conjunction or pairing of an old crescent Moon and Jupiter. They will be a lovely sight in the southeast around 5:00 AM.

The Albany Area Amateur Astronomers will hold their April meeting at 7:30 PM on Tuesday, April 21, at the Schenectady Museum. Walter Yund will talk about "Vintage Glass and Brass," a brief introduction to the rich world of antique telescopes: their makers, history, and current states of preservation. Come hear about the interesting history of these revered instruments and enjoy dozens of photographs of classic observatories along with images of the telescopes that made them famous.


All club meetings are open to all and there is no admission charge.

Skywatch line for Wed. and Thurs., April 15 and 16, 2009:
by Ray Bogucki

The innermost planet Mercury has always presented problems for observers. Because it is only 36 million miles from the Sun, Mercury never appears very far away from the Sun in our skies. Thus it is usually observable only in the evening or morning twilight. It has the highest orbital velocity of any planet at 30 miles/sec., compared to the Earth's 18 miles/sec. In addition it is much smaller than Earth with a diameter of 3,000 miles compared to Earth's almost 8,000 miles. Mercury's orbital period is only 87 days so that it completes a little over 4 orbital cycles while the Earth completes one.

Because it is an inner planet, Mercury will alternately pass between the Earth and Sun at inferior conjunction, and then behind the Sun at superior conjunction. It will pass through about seven conjunctions (of both kinds) in one Earth year. Each time it passes behind the Sun, it emerges into our twilit evening sky as an evening star setting after sunset. Conversely after each pass between the Earth and the Sun, it emerges into our twilit morning sky as a morning star, rising a little before the Sun. Just for the record, we might note that thirteen times each century, during an inferior conjunction, Mercury passes precisely between the Earth and the Sun and becomes visible as a small black dot crossing the face of the Sun in an event known as a transit. The most recent transit of Mercury occurred on Nov. 8, 2006 and the next transit will occur on May 9, 2016.

Currently, Mercury is appearing as an evening star in the evening twilight just after sunset. The current apparition presents the best opportunity to observe Mercury this year. Between April 19 and April 30, it will be far enough east of the Sun to be setting in a dark sky shortly after the end of evening twilight. From a site with a clear view of the western horizon, look for Mercury, currently with a bright magnitude of minus one, near the west-northwest horizon, roughly 14 degrees below the Pleiades. A telescope will show it approaching 50% illumination in a phase that appears like the first quarter Moon.

A final note on upcoming events - next Wednesday, April 22, offers a spectacular early morning of observing. The Lyrid meteor shower will peak in the early morning hours. The Lyrid meteors are generated when the Earth passes through debris left in its orbit by Comet Thatcher. While normally a modest display with perhaps a dozen meteors per hours, the Lyrids have, at unpredictable times, produced more active displays. Then, as twilight begins, the waning crescent Moon and brilliant Venus will rise very close together. Californians will see an occultation of Venus by the Moon, but we must settle for a spectacular close pairing. Both the Moon and Venus will remain visible to the naked eye in broad daylight, although binoculars will greatly enhance the scene.

This is the Skywatch Line for Monday and Tuesday, April thirteenth and fourteenth.
by Joe Slomka

The Sun sets at 7:36 PM; night falls at 9:18. Dawn breaks at 4:34 AM and ends with sunrise at 6:16.

Sunset finds two planets in the evening sky: Saturn and Mercury. Mercury is brighter but low in the West. It is beginning the best evening appearance for us mid-northerners. In a telescope, it appears almost eighty percent illuminated. Mercury sets about 8:53 PM.

The best time to view Saturn is between 10 PM and Midnight. Depending on size and power, telescopes can see at least one moon of Saturn - Titan. Titan is the largest moon in the Solar System. Astronomy magazines and websites provide diagrams and timetables for Titan and several of its fellow satellites.

Our Moon rises after Midnight. The waning Moon is about three-quarters illuminated. Tuesday's dawn has the Moon between Scorpius and Sagittarius; Wednesday sees it at the "spout" of Sagittarius' "teapot."

The hour before sunrise has Saturn setting in the West, and the rest of the Solar System - five planets- rising in the East. Jupiter and Neptune rise before dawn and occupy the same binocular or finder field. Venus rises after first light, but its brilliance helps find dimmer Mars and Uranus, eight degrees below. Mars and Uranus are about a half-degree apart and should be visible in a medium powered telescope.

Hydra, the Water Snake, wends its way southward beneath Cancer and Leo. Two constellations ride on its back, Corvus and Crater. Corvus is known as either a Raven or a Crow, due to conflicting legends. One story depicts the snow-white Raven as Apollo's messenger. When the Raven gives Apollo especially bad news, the angry god changed the Raven's feathers black (the color of contemporary ravens) and banished him to the sky. The other myth sees the Crow again as Apollo's messenger. When the god asks for a cup (Crater) of water, the Crow departs, but is distracted by a fig tree. The crow took too long. The fuming god banishes the bird and the cup to the night sky.

Clear Skies
Joe Slomka

This is Dudley Observatory's Skywatch Line for Friday, April 10, through Sunday, April 12, written by Alan French.

The Moon was full last Thursday so a waning gibbous Moon will dominate much of the night over the weekend. The Sun now sets just after 7:30 and the skies are almost completely free of the last vestiges of evening twilight before 9:00 PM. On Friday night the bright Moon will rise at 9:12, and it will rise a little over an hour later each succeeding night. By Sunday night moon rise will be at 11:24 and we'll have more than two hours of dark, moonless skies.

Saturn is well up in the east southeast by 9:00 PM. It lies below the conspicuous constellation of Leo, the Lion. The brightest star in Leo, is Regulus, meaning “little king,” which marks the heart of the lion. Regulus appears bright because it is one of our nearer stellar neighbors, lying only 77 light years away. Regulus is almost exactly on the ecliptic, which marks the apparent path of the Sun on its yearly journey through the stars, so the Moon often occults or passes in front of Regulus.

Regulus marks the end of a pattern of stars or asterism known as the Sickle of Leo. This backwards question mark shaped pattern of stars nicely outlines the head of Leo and is easy to pick out. To the left of the sickle a triangle of stars marks the lion's hindquarters. The brightest star in the triangle and the one farthest east is Denebola, which means “tail of the lion.”

Saturn lies below the hindquarters of Leo. Skywatchers with good memories may notice that Saturn looks dimmer than it has it past years. This is because part of Saturn's luminosity comes from its reflective rings. As Saturn and Earth travel around the Sun, our view of the rings changes.

The planet Saturn is tipped on its axis like out Earth. Its tip is almost 27 degrees. When we see Saturn tipped either 27 degrees away from us or toward us, our view of the rings is “open,” we see them in all their beauty, and Saturn appears brightest. Right now our view shows the rings tipped a bit less than four degrees, so they are less impressive through a telescope and the planet appears dimmer than usual.

Virtually any telescope magnifying about thirty times will reveal Saturn's rings. While they are not as impressive as they can be, it is interesting to see them appearing unusually thin and close to edge-on. The slender rings also make it easier to look for the often subtle details on in Saturn's atmosphere, and to spot some of Saturn's moons. Titan is within range of any telescope, and Rhea is also easy. Tethys and Dione are also relatively easy to spot in modest telescopes. Most planetarium software programs will show the location of Saturn's moons.

This is Dudley Observatory's Skywatch Line for Wednesday, April 8, through Thursday, April 9, written by Alan French.

The Moon will be Full late Thursday morning so bright moonlight dominates the night sky now. By 8:30 on Wednesday evening the almost full Moon will be well up in the east southeast. Spica, the brightest star in Virgo, the Maiden, will be to the Moon's lower left and not far above the horizon. By Thursday evening the rising Moon, just past Full, will be below Spica.

If you are up at 6:00 AM you'll find brilliant Venus seven degrees above the eastern horizon in the glow of morning twilight. Venus is now just past it closest approach to Earth, and is almost one arc minute in diameter. The human eye is capable of resolving one arc minute, so the disk of Venus is slightly too small to be detected by eye. However, even binoculars provide enough magnification to reveal the disk of Venus, and to reveal that we now see it as a very slender and lovely crescent. It is a lovely sight through any modest spotting scope or astronomical telescope.

We see Venus as a slender crescent because most of its sunlit face is away from us, and we see mostly the dark side of the planet away from the Sun. As the weeks go by Venus will be moving ahead of the Earth, thus moving farther away and becoming smaller. We will also see more and more of the sunlit face.

The other bright planet in the morning sky is Jupiter, which appears as the brightest star above the southeastern horizon. Mars is about one quarter to the distance right of Venus as Jupiter, but is now far from Earth and not very bright – especially against the glow of morning twilight. Mars will be slowly drawing closer to us and growing brighter during the rest of 2009. Mars will be closest to Earth in early 2010, but this opposition will not be a favorable one. At the closest and best, or favorable, oppositions, Mars appears 25 arc seconds in diameter. In 2010 it will only reach 14 arc seconds.

This is the Skywatch Line for Monday and Tuesday, April Sixth and Seventh.
by Joe Slomka

The Sun sets at 7:28 PM; night falls at 9:08. Dawn breaks at 4:47 AM, ending with sunrise at 6:26.

The Moon is tonight's most prominent feature. The twelve-day-old Moon is short of "full," and inhabits the sky below Leo. Dim objects cannot withstand the Moon's brilliance.

Saturn is one of the few objects to overcome the Moon's glare. Saturn appears above the Moon on both nights. Large binoculars and any telescope show the planet's ring system. Last month, the rings were edge on and difficult to see. Now, they are tipped about three and a half degrees, permitting some view of the rings. A telescope user can use high powers to see the ring's shadow upon the planet's clouds and some of its sixty-one moons. Astronomy websites and magazines predict when Titan, the largest satellite in our Solar System, casts its shadow upon Saturn.

Dawn depicts Saturn and the Moon preparing to set in the West, while Jupiter is rising in the East. Neptune follows Jupiter a short time later. The hour before Sunrise sees Venus and Mars join Neptune and Jupiter. While Jupiter is highest, Venus is brightest. High power binoculars and moderately powered telescopes view Venus as a very thin crescent. Mars is a much dimmer red spot fourteen degrees west and below Venus.

The unmistakable shape of Leo, the Lion, dominates the evening sky. If one looks past Denebola, the Lion’s Tail, one sees a faint hazy cloud. Binoculars show it to be a galactic star cluster, called Coma Berenices.

Unlike most constellations, Berenice was not mythical figure. She was married to Ptolemy III of Egypt. When her brother-in-law involved the Pharaoh in a war, Berenice, like all wives, worried about her husband in battle. She vowed to Aphrodite that she would donate a lock of her hair if Ptolemy arrived home safely. He did; and she fulfilled her promise. One day the royal couple inquired of the court priest-astrologer what happened to her donation. He replied by pointing to a hazy cloud in Leo and said the gods accepted her sacrifice. The modern Libyan city of Benghazi bears a modified version of her name.

Clear Skies
Joe Slomka

This is Dudley Observatory's Skywatch Line for Friday, April 3, through Sunday, April 5, written by Alan French.


The Moon was at first quarter last Thursday morning, so a waxing gibbous Moon will dominate the night sky over the weekend. On Sunday night the Moon will be near Regulus, the brightest star in Leo the Lion.

As you probably know, it is not safe to point a normal telescope at the Sun. The view would cause instant and permanent eye damage. There are special filters, however, designed to make solar viewing safe. These filters fit over the front of the telescope. They eliminate the infrared and ultraviolet light, and reduce the visible light by a factor of 100,000. Only with one of these filters, designed specifically for solar viewing, can the Sun be safely observed.

Solar filters provide a view of the Sun that reveals sunspots – dark spots – and plages – slightly brighter areas. The sunspots are areas where the magnetic field has decreased the flow of heat, so they are cooler and appear dark against the surrounding region. The spots usually have two obvious parts, a darker, inner umbra, and a lighter, outer penumbra. The larger spots frequently reveal a lot of intricate detail, which changes over time. The slightly brighter plages are hotter regions.

The solar activity and number of sunspots go in cycles. Right now we are in an unusually quiet spell, and sunspots have essentially vanished. NASA has announced that this is the quietest Sun – the deepest solar minimum – we've had in nearly one hundred years. Last year the Sun was spotless on nearly three quarters of the days. This year it has been even more free of sunspots, and we are going on three weeks without a single sunspot.

We had similar minimums back in the early part of the last century, and in the latter part of the 19th  century.  They were each followed by a robust solar maximum with a lot of sunspots.  Scientists expect we'll see the same thing happen this time.  Astronomy has changed immensely since the last such minimum, and scientists are far better equipped to study the Sun this time – with much more sophisticated equipment and spacecraft now dedicated to studying the Sun.

Amateur astronomers are also far better equipped to observe, photograph, and study the Sun.  In addition to safe solar filters to provide views in white light, there are special amateur telescopes that provide safe views of the Sun in the red light of glowing hydrogen.  This allows amateurs to see the lovely solar prominences that arc out from the limb of the Sun.  These features are simply too faint to see in a normal, white light view, and are only revealed when we view the Sun in their prominent red color.

SKYWATCH LINE for Wed. and Thurs., April 1 and 2, 2009:
by Ray Bogucki

A quick overview of the month of April shows many fascinating aspects of the movements of the planets and their satellites. Mercury, our innermost planet passed behind the Sun at superior conjunction on Monday and is still hidden in the glare of the Sun. It will, however, be vaulting rapidly into the western sky after sunset. By next week, this diminutive planet will be setting a half-hour after the Sun, and in 2 weeks, will set more than an hour after sunset in what promises to be the best apparition of Mercury for this year.

The only planet which is in good observing position in the evening is Saturn, which is well up in the southeast at the end of evening twilight, a little to the left of the bright star Regulus in Leo the Lion. Because the plane of the planet's rings is tilted at only 3 degrees to our line of sight, the rings appear very thin. This significantly diminishes the brightness of Saturn, but makes it easier for telescopic observers to note the faint cloud bands that encircle the planet parallel to its bulging equator, and to find the faint inner moons of Saturn which are usually hidden by the glare of the rings when they are more open.

The rest of the bright planets will be found in the early morning sky. Giant Jupiter now rises in the east-southeast 2 hours before sunrise, while the sky is still dark. Its bright magnitude of minus 2 makes it easy to find. The ever-changing arrangements of its four large moons have been followed with interest by observers since Galileo first discovered them in 1609.

Mars rises about an hour before sunrise when morning twilight is brightening. It can be found with binoculars a half hour before sunrise, below and well to the left of Jupiter. However, since Mars is near the far side of its orbit, its disk is very small, only 4 arc-seconds, so little meaningful observation can be done even with a large telescope.

The super brilliant Venus, which just passed between the Earth and Sun at inferior conjunction last week, has moved to the west of the Sun to become a morning star. It rises just about the same time as Mars, but about 20 degrees along the horizon to the north of the Red Planet. While Mars will continue for a while to rise about an hour before sunrise, Venus will rapidly move upward in the morning, rising a half-hour before Mars by mid-month. It will serve as an excellent guide for finding Mars. For example, on April 25, Mars will rise just 4 degrees directly below Venus.