Skywatch April 2002

These scripts are written by members of the Albany Area Amateur Astronomers and read by the staff of the Dudley Observatory. All scripts are copyright and may not be reproduced without permission of the writer and the Dudley Observatory. Scripts are published to the web in the week following their recording. Daily scripts may be heard by calling 518-382-7584 after 5pm.

 NOTE: Times given in the scripts are all local Schenectady, New York time.

Monday, April 1st. Written by Joseph Slomka.

The Sun sets tonight at 6:22, with night falling at 7:59. The Moon rises after midnight and poses no problems for observers. Dawn breaks at 3:59 AM, and ends with sunrise at 5:36.

As the sky darkens, Jupiter shines brightly overhead. Saturn lies lower to Jupiter's west, while Mars is found halfway between the zenith and the horizon. Venus is the brightest object in the sky, but hovers just above the horizon. This is a good apparition for Venus. It becomes better as Spring progresses. Tonight, Venus appears almost full to the telescope observer. As the month continues, Venus will become progressively thinner, but brighter.

Comet Ikeya-Zhang appears a bit lower and to Mars' west. The comet will do something interesting; it will set only briefly tonight. This week, the comet will pass just North of the Sun and then continue out to the far reaches of the Solar System. If you had a flat horizon, you would see the comet get lower in the West, set very briefly and then rise before the Sun. In fact, it is possible for the lucky observer to see the comet this evening and then in the dawn, weather and obstructions permitting.

High in the eastern sky is a wonder accessible only to telescopes six inches in size or larger. This is the Virgo Cluster of Galaxies, an area of sky located midway between Leo, the Lion's, tail and the star Epsilon in Virgo. In this small area of the sky are about 3000 galaxies, about 100 of which are visible to amateur telescopes. Some galaxies are clearly visible, while others are mere pinpoints of light. Each galaxy is made of millions of stars, many probably with planets. This cluster hints at a larger structure to the universe. Astronomers now realize that galaxies are not "island universes". Our own galaxy is part of the "Local Group." Apparently, these groups bunch into larger structures. Now, astronomers talk of "cosmic strings" in which galaxies are connected in long, string- like filaments which stretch over millions of light years in length.

Tuesday, April 2nd. Written by Jonathan Cassidy.

At the zenith, directly overhead, is the constellation Leo the lion. This constellation is one of the easier figures to see in the night sky.

To identify Leo start with the visible stars that form a backward question mark "?" Directly overhead. This is the head, mane and chest of the lion. Going to the west find a right triangle of two bright stars and one dimmer at the right angle and you have the lion by the tail. WATCH OUT he could be dangerous. The last star of the triangle is called Denebola, meaning "the lion's tail". In the backward question mark the brightest star of the constellation is Regulus, having a meaning of "little king".

On a Sumarian goblet, of 4000 B.C. and again on carved on Persian architectual stone, of 500 B.C., there are images showing a lion and bull (Taurus) in mortal combat. Thus there is importance to the place in the sky of Leo with relationship to Taurus. This has been noted over a long period of time by vastly different cultures.

Wednesday, April 3rd. Written by Alan French.

During the hours just after sunset and just before sunrise we can often see satellites traveling across the night sky. Indeed, anyone who spends some time watching the sky during the early evening or late morning hours is bound to see a satellite or two. They appear as a star that is moving slowly across the sky. Some are as bright as the brightest stars, and some are just bright enough to be visible.

We see satellites because they are high above our heads where the Sun is still shining. The Sun has set for us and we are in the Earth's shadow, but the satellites are still in sunshine and are quite easily visible to us down in the darkness. Tonight we have two chances to see the International Space Station. During the first pass the ISS will pass high overhead and will be bright and very easy to spot. On the second visible pass, it will be low in the sky and not as bright or as easy to see - but it would be fun to see the ISS twice in one night.

The ISS will first appear above the west-southwestern horizon at 6:47:30 PM. It is generally hard to see at first appearance, so you may have to wait a minute or so before you spot it coming up from the horizon. It will be highest at 6:50:39 when it will be 69 degrees above the north-northwestern horizon. It is easiest to spot when it is highest - simply look for a very bright star almost overhead moving toward the northeast. The ISS will vanish above the northeastern horizon just before 6:54 PM.

The ISS will make its second appearance of the evening at 8:24:47 above the west-northwestern horizon. It will be at its highest, and easiest to spot, at 8:27:12 PM, when it will be only 20 degrees above the north-northwestern horizon. Simply look for a modestly bright star moving toward the north-northeast not far above the horizon. The ISS will vanish into the Earth's shadow before reaching the north-northeastern horizon.

You can obtain satellite predictions for your location by visiting www.heavens-above.com It includes predictions for the ISS and many other satellites. Perhaps the most interesting satellites to watch are the Iridiums. These numerous satellites, originally placed in orbit for satellite phone service, have a highly reflective antenna about the size of a door. When the geometry is right, the antenna catches the sunlight and the satellite may "flare" briefly to appear far brighter than any of the stars. A bright Iridium flare of magnitude -8 or -9 is a very impressive sight. Because the paths of these flares are rather narrow, be sure to carefully enter your location when obtaining predictions for these satellites.

While many satellites do not vary much in brightness as they cross the night sky, some vary greatly in brightness. Many of these are satellites that are no longer in use, or simply spent rocket boosters, so they are no longer controlled and are allowed to tumble as they travel above our Earth. Tumbling satellites are a lot of fun to watch. Some tumble rapidly and change brightness quickly. Others vary in brightness at a more sedate pace.

Thursday, April 4th. Written by Peter Jennes.

Sunset for tonight, Thursday, April 4th was at 6:25. The Moon is just past last quarter and does not rise until nearly 3 AM. If you are curious about the Moon’s location this evening, just look for Jupiter. By chance, the Moon is almost directly opposite Jupiter tonight and a line drawn perpendicular to the ground from Jupiter points at the Moon. In a telescope, four of Jupiter’s own moons will be visible. These four moons, Io, Europa, Ganymede, and Callisto were first observed by the Italian scientist, Galileo in 1610.

The telescope used by Galileo was very simple and was made up of a convex front or objective lens and a concave eyepiece lens. This design produces an upright image and is still widely used in opera glasses. Opera glasses, although they look like binoculars, do not have the same optical quality as binoculars but they are lighter in weight. Like Galileo’s telescope, opera glasses have low magnification. In fact, Galileo’s telescope is thought to have only had about 15 to 30 power magnification.

Given the quality of glass and lens grinding available during the early sixteen hundreds, it is amazing that Galileo was able to make any discoveries. However, Galileo was able to report that the moon was not perfect, and that Saturn had strange bulges that were later found to be rings. Perhaps the most important observation made by Galileo was that the moons of Jupiter were in fact revolving around Jupiter. With this one observation, the stage was set for the final proof that the Earth was not the center of the Solar System let alone the center of the universe.

Today, it is difficult to imagine Galileo’s personal struggle to overcome thousands of years of preconceived ideas to understand what he saw in his telescope. However, we can put the effort into context by considering that even after four hundred years of scientific advancements, modern astronomers are still struggling to understand Jupiter and its moons. Because of Galileo’s dedication to the truth, the astronomical community rewarded him by grouping Jupiter’s four major moons under the title, Galilean Satellites. Symbolic to his efforts, the Galilean Satellite group is the largest object in our solar system named after an actual person.

Friday, April 5th to Sunday, April 7th. Written by George Mileski

Asteroids also known as minor planets are small irregularly shaped rocky bodies that orbit the sun. Most of them orbit the sun in a band between Mars and Jupiter called the asteroid belt. The first asteroid was discovered by a Sicilian astronomer named Giuseppi Piazzi in 1801, he discovered Ceres. Some 10,000 asteroids have been catalogued with dozens more being discovered every month or two. They are thought to be debris left over from the formation of the planets. The composition of asteroids are rocky, consisting mostly of silicates, some are metallic, mostly iron and nickel, and some combine rock and metals.

The name ''asteroid" means "starlike" which aptly describes their appearance. The four biggest asteroids are Ceres, about 580 miles in diameter, Pallas 327 miles, Vesta 317 miles and lastly Hygiea 244 miles in diameter. There are probably several hundred thousand asteroids of all sizes. Vesta is half the size of Ceres but appears in binoculars brighter because it is composed of lighter colored rock. Ceres, Pallas and Vesta are easy binocular objects.

Information for finding asteroids are in manuals such as "The Observers Handbook" "Astronomy" and "Sky and Telescope" magazine. Not all asteroids are located safely beyond Mars. Thousands of small asteroids are in orbits that cross or come close to the earths orbit. These are named NEO's or Near Earth Objects and they include about 416 that have been classified as "potentially hazardous asteroids" or PHA's, meaning that some day there paths might take them uncomfortably close to earth or they might even strike our planet. At rare intervals, a small asteroid or its also called a "meteoroid" smashes into earth. One of these impacts caused the famous Meteor Crater in northern Arizona, near Flagstaff over 25,000 years ago. One of the biggest events in earths history happened about 65 million years ago, when an asteroid about 6 miles wide struck earth in Mexico's Yucatan Peninsula destroying about 70% of all living things.

In the news tonight as I'm writing about asteroids the scientists say that there is an asteroid called 1950 DA that has a 1 and 300 chance of hitting earth in the year 2880. The asteroid is six tenths of a mile wide.

In the northwestern sky is the comet Ikeya-Zhang. My binoculars have a 7 degree field, when I focus on Venus and move right about 4 fields along the horizon and then raise them up slowly, you should be able to find the comet.

Monday, April 8th. Written by Joseph Slomka.

The Sun sets tonight at 7:30 PM, now that Daylight Savings Time is in effect. Night falls at 9:09. Dawn breaks at 4:45 AM, and ends with sunrise at 6:24.

As the sky darkens, a line of bright planets extends from Jupiter overhead to Venus in the Northwest. Jupiter appears as the brightest object in that part of the sky; binoculars show the four moons. Saturn appears below and to Jupiter's West; it shines above and is brighter than the star Aldebaran. Mars is found about halfway between horizon and Saturn; it appears as a small, red dot. Finally, one can spot Venus if the northwestern horizon is free of obstructions. Venus is the brightest object in sky, but quite low.

In the darkening sky, Comet Ikeya-Zhang is visible low in the Northwest. Like Venus, trees or buildings could hide it. The comet appears just below the "W" shaped constellation Cassiopeia. Just scan the area with binoculars, the comet appears as a fuzzy star with a tail pointing away from the site of sunset. One must work quickly, Comet Ikea-Zhang sets soon after twilight's end. However, intrepid observers can observe the comet before sunrise. At 5AM, the comet is about twenty degrees high in the northeast. Again, the comet will resemble a fuzzy star with a tail pointing away from the sunrise. An added treat is the Andromeda Galaxy only seven degrees below the comet. Binoculars should provide an interesting sight.

Rising in the east is the great constellation LEO. From ancient times, this group of stars has been associated with royalty and mighty power. For the Egyptians, Leo represented the "House of the Sun"; the ancient Hebrews considered it the symbol of the "House of Judah", the lineage of King David and the Messiah. Leo is easily identified. The head is marked by a backwards question mark, with Regulus, the brightest star, at the bottom. The lion's body extends eastward and ends in a triangle, with DENEBOLA, the constellation's second brightest star, marking the lion's tail. In fact, the Arabic word DENEBOLA means "the lion's tail".

Tuesday, April 9th. Written by Jonathan Cassidy.

New moon coming this week thus it is a good time to look for dim patterns of stars. Directly over head is the bright star Regulus in the constellation Leo. To the north of Regulus is the familiar bowl of the big dipper.

Between the lion and the bowl are three sets of close spaced double stars. These sets are about a closed hand away from each other and each has a brighter and dimmer star. These three sets are depicted as either the paws of the bear, URSA Major, or as "three leaps of the gazelle", hoove marks in the sky. You will not see these pairs of stars when the moon is shining bright or under street lights.

Over millenium constellations have been formed by different cultures and later changed or deleted from the night sky. The old constellation Argo Navalis is now Vela, Puppis, Carina and Pyxis.

You too can make your own constellations or asterism out of pictures you see in the night sky. Your star chart can help you navigate the night sky and tell stories you find interesting.

Wednesday, April 10th. Written by Ray Bogucki.

The lineup of the bright planets continues to tighten in the western sky this week. Jupiter is highest, about 40 degrees above the western horizon. Dropping toward the west-northwest, in order, are Saturn, near Aldebaran, the red eye of Taurus; Mars, just south of the Pleiades; and Venus, now shining at a brilliant magnitude of minus 4, and setting about an hour and a half after the Sun. Mercury passed behind the Sun in superior conjunction last Sunday and, moving rapidly eastward, will shortly emerge from the Sun's glare to join the line of planets.

The Moon will be new on Friday, and by sunset on Saturday, the new young sliver of a waxing Moon will act as a guide, lying just a few degrees east, or above and to the left of Mercury, which you might catch with binoculars in the bright twilight about 20 minutes after sunset. The planets are spaced so that the Moon will visit each one, in order, on successive evenings. It will pass just south of Venus on Sunday, just south of Mars on Monday, and north, very close to Saturn on Tuesday. After passing just north of Jupiter on Thursday, it will add itself to the lineup of solar system objects for the next few nights. By then Mercury will be easily visible below Venus, providing a beautiful delineation of the ecliptic with a line of six objects.

Meanwhile, a seventh object, the comet Ikeya-Zhang, is visible very low above the north-northwest horizon as the evening twilight fades. Actually, it rises again after midnight and is better viewed about 4 a.m., where it now lies on a line drawn from Gamma, the star at the middle of the "W" in Cassiopeia, through Alpha, the next star in the "W" lying to the southwest. Extend the line about one-and-a-half times the distance between the stars to find the comet. It is visible to the unaided eye, but the view of the tail is improved with binoculars. It is now leaving the Sun, moving about 2 degrees to the East daily, and will be at its closest approach to Earth, about 37 million miles, on April 29. Look for it soon because it won't return to the inner solar system again until the year 2343.

Thursday, April 11th. Written by Peter Jennes.

Thirty-two years ago today, Apollo 13 began its ill-fated journey to the Moon. Although that mission gave us the phrase "Houston, we have a problem" and a frightening look at the limits of technology, the scientific return of the Apollo program revealed the true value of space exploration. In return for the risks, Apollo gave us a look at the origin of the Moon and its implications for the rest of the solar system. Before Apollo, there were several competing theories for the Moon’s formation. However, after the Apollo discoveries, all previous theories had to be dismissed. In their place, research on the Apollo samples provided a new theory about the Moon’s formation that revealed the chaotic beginning of our solar system.

In the new theory, a planetoid about the size of Mars had a grazing collision with the proto-Earth. The collision destroyed the planetoid and the resulting fragments coalesced into our nearest neighbor. One of the strongest pieces of evidence for this collision came from the chemical makeup of the lunar samples. The total lack of water in every sample indicated that the entire lunar surface had been molten. When combined with other evidence, the most logical solution became the collision theory of lunar formation. While this theory may sound simple, the implications are quite profound.

Before the new theory, the assumption was that all of the planets formed pretty much where they are now. Based on the new theory, scientist realized that the early solar system must have been a very chaotic neighborhood. With hard evidence that something moved an object the size of Mars onto a collision course with Earth, scientist began to look for evidence of similar collisions elsewhere in the solar system. Finding other examples wasn’t hard.

Venus was found to rotate backwards. Observations showed that the spin axis of Uranus points towards the Sun and that Neptune’s axis is highly inclined. Other clues may lie in the eccentric orbit and strange combination of Pluto and Charon, the offset magnetic poles of Uranus and Neptune, and the fragmented surfaces of many outer moons. Looking at these puzzle pieces, the most important lesson from Apollo may be the need to watch for the unexpected in our chaotic solar neighborhood.

Friday, April 12th to Sunday, April 14th. Written by George Mileski

At this time in the spring the big dipper is nearly overhead. Its system of pointer stars provide the best opportunity to linkup all the major stars and star groups above the horizon. The big dipper itself is not a true constellation. Such a group of stars is called an asterism. However the dipper and related stars with it forms the constellation "Great Bear" or Ursa Major, as it is called. The dipper is the invention of 19th century stargazers. In Britain the seven dipper stars are known as the plough. North American native peoples pictured the bowl as a bear and the three handle stars as a trio of braves stalking the beast. They must of had vivid imaginations.

A mental extention of the curve of the big dipper handle will bring you to zero-magnitude Arcturus, the fourth brightest star in the sky. Arcturus is the most prominent star in the constellation Bootes, the herdsman. Its name and location can be memorized with the phase "follow the arc to Arcturus" which refers to the arcing curve made by extending the big dipper's handle. If you keep extending the curve you will go on to Spica, a first-magnitude star, located in the constellation Virgo. Extending the curve further will bring you to Corvus "the Crow" its stars are third-magnitude. Corvus's identity can be confirmed by using its top two stars as pointers back to Spica. 

The two stars in the big dipper's bowl nearest the handle can be used to form a line 45 degrees south to Regulus, the first-magnitude star in Leo the lion. A backward question mark signifies the beast's head and mane, while Regulus is Leo's heart. His hindquarters are designated by a triangle of stars to the east. Leo is the most prominent of the spring constellations and the only one in the spring sky that resembles the object for which it was named. Again if you trace diagonally across the dipper's bowl the mental line you trace will lead you to Castor and Pollux in the constellation Gemini, a link between winter and spring constellations. The two end stars of the bowl of the big dipper will point you to Polaris, the north star, which happens to be the end of the handle of the little dipper. 

So you can see by using the big dipper's stars as a guide , it can familiarize you with many stars and constellations in the sky. On Friday the 12th, in the western sky the planets are lined up diagonally, starting with Jupiter, Saturn, Mars and Venus. There is also a new moon on Friday. On Saturday the young moon will be below Venus, use binoculars for this. Mars will be near the Pleiades, both will be in your field of view in binoculars. The comet Ikeya-Zhang is located below Cassiopeia, this is at 8:30 at night in the northwest.    

Monday, April 15th. Written by Joseph Slomka.

The Sun sets tonight at 7:38, with night falling at 9:20 PM. Dawn breaks at 4:31 AM, with sunrise taking place at 6:13.

As night falls, even casual observers will notice that the sky is quite crowded. All of the easily observed planets are visible. Jupiter shines brightly almost overhead, followed by Saturn a bit dimmer and lower just to Jupiter's West. Mars is midway between Jupiter and the horizon. Venus is the brightest object in the sky, to Mars' lower right. Mercury is the last in line, hovering above the northwestern horizon. Mercury is so low that buildings, trees or hills could hide this elusive member of our solar system.

Comet Ikeya-Zhang appears low in the northwest, below the "W" shaped constellation, Cassiopeia. It is so low, that trees or hills may hide it. As night wears on, the comet skims the northern horizon and then climbs higher in pre-dawn skies. By the beginning of Dawn, it rides 34 degrees above the Northeast.

Mars attracts our attention due to its neighbors. The Moon is two and a half degrees to Mars' lower left. Only three days old, the Moon is a thin crescent; it may be difficult to see after sunset, but becomes easier as night falls. To Mars' right, the beautiful star grouping, the Pleiades, appears.

Rising in the east about 9:00 PM is the object astronomers call M45, but is commonly called the Pleiades. The Pleiades form a mini dipper that is so distinctive that virtually all cultures named and worshiped it. Many cultures used it as a calendar. When the Pleiades rise in the Fall, it is time to harvest. When it sets in the Spring, it is planting time. Ancient Greeks called it the "Seven Sisters", and other cultures had similar names, giving rise to the legend of the "Lost Pleiad". One of the stars has apparently dimmed in the past, because most people can see only six stars without optical aid. Most likely, the star known as Pleione was brighter in ancient times and recently dimmed.

Tuesday, April 16th. Written by Jonathan Cassidy.

Moon & Saturn

The moon will come very close to the planet Saturn tonight. This close approach is called a conjuction. If the moon covered up Saturn it would have been called an occultation. A conjuction is when two celestial bodies have their least spacial separation.

This conjuction will happen in the western sky and will be seen best with good low horizon in that direction. Tonight Saturn will be just below the moon. For those without binoculars or telescope you will see only two stars near the moon. The closer one is Saturn and the other is Aldebaran, the eye of Taurus the Bull.

The moon moves at a different speed than the stars and planets. Over the course of the early night if you watch for several hours you would be able to note the change of position of the moon related to Satrun and Aldebaran. A simple set of drawings of the three when they first appear in the sky and just before setting will show you this movement with out having to stand out the whole time.

Later this week watch the moon close on the planet Jupiter. In ancient times great significance was given to conjuctions and occultations. When these happened in a particular constellation like Leo, the lion, there was expected to be a "happening" with relation to the ruler or king of a country.

Wednesday, April 17th. Written by Ray Bogucki.

In this evening's western sky, the crescent Moon will stand halfway between Jupiter and Saturn, adding to the elegant lineup of all the bright planets. Another solar system event will occur next Monday, when the Earth passes through the debris left by Comet Thatcher, giving rise to the April Lyrid meteor shower. This shower is rather modest in the number of meteors visible, but unlike the Leonids, which have a sharp, short period of maximum activity, the Lyrids can be observed for a couple of days before and after the maximum. The Moon will be two days past first quarter on Monday and the bright moonlight will interfere with the visibility of the fainter meteors. The optimum viewing time will be early Monday morning during the short window between moonset, about 4 a.m., and the onset of morning twilight, about three quarters of an hour later.

While the bright moonlight spoils the viewing of most faint objects, the period of a few days before and after the first and last quarter Moons present an excellent opportunity to get a close-up view of the only celestial object whose surface can be studied in great detail with a small telescope or even with binoculars. The deep shadows cast by the mountains and craters near the edge of the sunlit portion of the Moon create a realistic 3-dimensional effect. The lengths of these shadows provided early astronomers with their first means of estimating the heights of surface objects on the Moon. Many craters have tall central peaks and the change in the lengths of their pointed shadows on the crater floors can be detected in a few hours of observing as the position of the Sun changes.

Thursday, April 18th. Written by Peter Jennes.

If you have been following the western line up of planets, you have undoubtedly noticed that the Moon has joined the lineup. At the same time, Mercury is also moving into the gathering but Mercury is an elusive target that requires a clear western horizon. To find Mercury, use binoculars and scan the sky above the sunset point. If you spot what looks like a star about one hand-width above the horizon, that will be Mercury.

While Mercury will be very difficult to see until next week, the Moon and Jupiter are impossible to miss. At sunset, both objects will be high in the southwest and separated by about one degree. With a low power telescope, our Moon and the four Galilean moons of Jupiter should fit in one field of view. In this single view, you are seeing an amazing range of geology. Our own Moon is nearly inert and composed of mostly rock and light metals. At the opposite end of the spectrum is Io with an iron core and silicate crust. Close up views provided by space probes reveal a moon being pushed and pulled by massive gravitational forces. These forces drive an astounding number of volcanoes and make Io the most geologically active moon in the solar system.

In contrast to Io, Europa has a tranquil surface almost free of craters. Instead, Europa has an icy surface of mottled plains. Scientist suspect that under Europa’s frozen surface there may be a primeval ocean holding untold mysteries. While Europa is nearly the same size and density as our Moon, Ganymede is larger than both Mercury and Pluto. The active surface of this giant moon is an amazing patchwork of light and dark terrain. This stark contrast in color indicates that Ganymede is a complex mix of rock and ice wrapped around a partially molten interior. The final Galilean moon, Callisto, is very similar to Ganymede in size. Unlike Ganymede, the surface of Callisto is uniformly cratered and shows little geologic activity. Callisto may owe its stable surface to the fact that it orbits Jupiter at a greater distance than any of the other Galilean moons and has therefore escaped the intense tides the other Galilean moons experience.

Friday, April 19th to Sunday, April 21st. Written by George Mileski

In the west we have a string of pearls, five of the nine planets of our solar system can be easily seen. The first pearl in the string of pearls is Jupiter in the constellation Gemini, shining at magnitude -2.6. With binoculars mounted on a tripod, you can see Jupiter's four moons. They are interesting to see because there positions are always changing as they orbit their mother planet. 

The next pearl west of Jupiter is Saturn, it is especially interesting when looking at it with a telescope. To make out the rings you need at least 40 power for a decent look. West of Saturn in Taurus the bull, is the eye of the bull, a star called Aldebaran.  

The next pearl west of Saturn is Mars, it is the dimmest of the five planets I'm describing. The Pleiades or the Seven Sisters is about two degrees or so northwest of Mars. It looks like a minature dipper. Its a nice sight in binoculars. 

Venus is the next planet in our string of pearls. You can never miss Venus because it is so bright. Of the nine planets it is the brightest one. Venus is in the constellation Aries.  

The last planet west of Venus is Mercury. Mercury will be visible in the west for several weeks. About the middle of May it will disappear into the horizon later to be seen in the morning sky. If you wait about 40 minutes after sunset you should be able to see Mercury with binoculars. It is located below Venus a little to the right.  

On Friday the moon is near Caster and Pollux in Gemini. Saturday nights moon is at first quarter, it will be in Cancer near the Beehive or Praesepe star cluster. On Sunday the moon will be in Leo the Lion, near Regulus the brightest star in Leo. The comet Ikeya- Zhang is located between Cassiopeia and Cepheus, heading for Cepheus. It is best seen at this time in the early morning before twilight.  

Monday, April 22nd. Written by Joseph Slomka.

The Sun sets tonight at 7:46; night falls at 9:31 PM. Dawn breaks at 4:17 AM, and ends with sunrise at 6:02.

The remarkable alignment of easily visible planets continues. Jupiter still occupies the highest spot, almost overhead in the West. Saturn is dimmer, and lower in the West than it has been for the past few weeks. Mars is still dimmer about six degrees below Saturn. Venus is the brightest object in the northwestern sky, and is found about 21 degrees above the horizon. If you have binoculars, the beautiful Pleiades star cluster can be found about four and a half degrees above and to Venus' left. Finally, Mercury shines about fourteen and a half degrees above the horizon, but it could be blocked by trees and hills.

The Moon is located in Leo's middle. It is about three-quarters illuminated, blocking out views of galaxies and similar dim objects. However, the Moon sets about dawn, providing dark skies for Comet Ikeya-Zhang. The Comet is now best seen in early dawn skies. At 4:17 AM, the comet is about fifty degrees high in the northeast. It is now dimming, due to the fact that it is receding into the cold far reaches of the Solar System. Binoculars will help city and suburban dwellers make out the fuzzy head, and tail. Those lucky enough to live in rural skies may not need aid in seeing the comet.

While hunting for the comet, one may see a meteor or two streak from the constellation Lyra, just above the comet. This is no illusion. The peak of the Lyrid meteor shower happened yesterday. The Lyrids are a notoriously sparse shower. But, a few meteors will linger, reminding us that meteor showers are frequently associated with comets. As comets pass by, they leave a trail of debris. If the Earth plows through that debris trail, the particles of comet dust burn up in our atmosphere, becoming meteors.

Tuesday, April 23rd. Written by Jonathan Cassidy.

The waxing gibbous moon is up this week. This washes out all but the brightest stars. So we are looking for the bright stars we use as sign posts of the sky.

Tonight coming up in the east is bright Arcturus. Note how a line drawn along the curve of the handle of the big dipper and extended will bring you to Arcturus as the next bright star. Straighten the line at Arcturus and speed on toward the horizon and you will find the next bright star Spica. Thus we say "Arc to Arcturus and speed on to Spica".

This is the way amateur astronomers, like myself, find our way around the night sky. We use the bright stars as sign posts to get to dim interesting things like galaxies.

With Arcturus and Spica as two stars of an equilateral triangle find Denebola to the west, near the zenith of the sky and the moon on the 23rd. Denebola is dimmer than the other two but should still be easy to find.

Inside this triangle is a particularly rich area of dim objects for telescope viewing. The group is known as the Virgo Cluster of Galaxies. In this area we can find so many galaxies that several can fit in one eyepiece field of view, but they are so dim that they are difficult or impossible to find with binoculars or small telescopes.

Wednesday, April 24th. Written by Ray Bogucki.

At this time of year, near midnight, the Earth assumes an interesting orientation in space at our location. The Milky Way, which was drooping low in the western sky at nightfall, has arrived at the western horizon and the entire 360-degree sweep of the Milky Way is arranged along our horizon in all directions. If we look anywhere along the horizon, we are looking through the spiral arms of our galaxy and the North pole of our galactic axis is overheard near the zenith. It is a great time to catch a sense of our spiral galaxy spinning like a Gargantuan top, turning once in 200 million years.

Riding high in the southwestern sky, and thus not obscured by intervening clouds of gas and dust that lie in the plane of the spiral arms, sits the constellation Leo, the Lion, one of the brighter of the 12 constellations of the Zodiac and a dependable harbinger of Spring at our latitude. Leo is easily recognized by its familiar asterisms of a sickle, or backward question mark, with a large right triangle of stars lying close by to the east. The stars in Leo provide a good example of the relationship between luminosity, distance and magnitude.

The brightest star in Leo is Regulus at the bottom of the handle of the sickle. Regulus is an impressive star, about 5 times the diameter of, and 130 times more luminous than, our Sun. At a moderate distance of 85 light-years, its size and luminosity allow its light to arrive here at a brightness of almost first magnitude.

While eta Leonis, the star directly above Regulus in the handle, appears much fainter, it is, in fact, much more luminous than Regulus. This huge supergiant is blazing ten thousand times brighter than our Sun but its staggering distance of over 2,000 light-years reduces its apparent brightness to a modest magnitude of 3.

At the other end of the scale is a star designated Wolf 359, located a bit below a line drawn from Regulus to the adjacent triangle.. At only 7.7 light-years distant, it is the third nearest star to our Sun, yet it can be observed only through a large telescope because it is a tiny red dwarf star, perhaps the size of Jupiter, emitting a feeble red light, with only about 2 thousandths of 1% of the luminosity of our Sun. Red dwarfs are calculated to be 10 times more numerous than ordinary stars like our Sun, but are rarely observed because they are so faint.

Thursday, April 25th. Written by Peter Jennes.

Tonight the Moon is nearly full and sits 20 degrees up in the east as the sky becomes dark. Although moonlight will wash out most stars, first magnitude Spica should be easily visible 5 degrees below the Moon. Spica is the brightest star in Virgo and represents a sheaf of wheat held in the virgin's hand. About 20 degrees to the west of the Moon and Spica lies the constellation Corvus. The stars of this mischievous crow form a dim parallelogram of third magnitude stars.

In the stretch of sky between Spica and Corvus, the Virgo galaxy cluster begins its trail across the sky. The Virgo Cluster is one of the nearest and most spectacular galaxy clusters known. The Virgo Cluster contains hundreds of significant members and many more lesser members. In comparison, our own Local Cluster of galaxies contains just three bright members and about three dozen lesser members.

With the Moon in the middle of the Virgo Cluster, it will be next to impossible to find any members of this cluster tonight. However, if you use the Moon to zero in on the location of Spica and the stars of Corvus, you will have a much easier time locating this region when the Moon is not present.

The trail of galaxies belonging to the Virgo Cluster begins just off the upper left corner of Corvus with M104, the Sombrero Galaxy. M104 is a compact galaxy and at eighth magnitude, M104 shows up in almost any telescope. Larger instruments reveal M104's prominent dust lane and bright central bulge. The heart of the Virgo Cluster lies about 25 degrees north of M104 between third magnitude Vindemiatrix and second magnitude Denebola.

The heart of the Virgo Cluster holds many bright galaxies. One of the brightest members of the cluster is the ninth magnitude elliptical galaxy M85. This elliptical is located at the northern end of the cluster. A few degrees south of M85 lies M87, one of the Cluster's most interesting members. M87 is a huge, peculiar galaxy with an active core. At least 1,000 globular clusters orbit M87 and a million solar mass black hole is thought to lurk at the center of the galaxy. Surrounding these galaxies is a host of additional galaxies waiting to be observed.

Friday, April 26th to Sunday, April 28th. Written by George Mileski

The ecliptic is the boulevard in the sky. In an oversimplified sense our solar system is like the surface of a wide , circular racetract, and the planets are the race cars. Sometimes Venus overtakes earth, sometimes earth passes Mars but all the action happens in the same 18 degree horizontal plane. Thus the planets, the sun and the moon are always seen in a restricted band in the sky corresponding to this plane.

The stars that form the backdrop for the ecliptic are known as the Zodiac, this is the band of 12 constellations. The Zodiacal belt with its unchanging constellations forms the background across which the planets appear to be forever wondering as seen from earth. Right now we have five planets that we can see at night. In the west, Jupiter is seen in the constellation Gemini, next further west is Saturn in Taurus, then Mars also is in Taurus, Venus is next in Taurus, and furtherest west and near the horizon is elusive Mercury in Aries. Venus and Mercury located between the sun and earth are the inner planets. They never appear far away from the Sun. The other planets, that is Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto are the outer planets.

The outer planets need more time than earth to complete their trip around the sun, which is their year. It takes Jupiter about 12 years to complete its trip around the ecliptic, spending one year in each Zodiac constellation. Jupiter is the brightest planet that can be seen throughout the night. Venus is brighter but can only be seen for just a few hours, either in the hours before sunrise or after sunset. Venus deviates at most 9 degrees from the ecliptic either way. Mars, Jupiter, and Saturn deviate less than that. The moon deviates about 5 degrees from the earths orbit. They are all found within the 18 degree wide belt.

On Friday the 26th there is a full moon. The planets in the west at this time span about 45 degrees apart from Jupiter to Mercury. They will be closing in, in May to about 33 degrees. The comet Ikeya Zhang can be seen before dawn in the constellation Cepheus. To find it look north and if you are familiar with a star map its near the star "eta" in Cepheus on Friday and is moving toward the constellation Draco

Monday, April 29th. Written by Joseph Slomka.

The Sun sets tonight 7:54; twilight ends at 9:43. Dawn breaks at 4:02 AM, and ends with sunrise at 5:51.

As the sky darkens, the planetary alignment lowers daily. Jupiter is high in the West - no longer overhead. While not the brightest planet, it is first to pop into view. Venus is next to be seen, twenty degrees above the western horizon. Saturn and Mars are located between Venus and Jupiter. Saturn is brighter. Both are less than a degree apart. You can see both planets in one binocular field. Mercury makes its best appearance of the year. It lies about six degrees below Venus. Mercury is a bright planet, but the low position makes it easy to hide behind hills, trees, and buildings.

Comet Ikeya-Zhang can still be observed in the pre-dawn northeast, between constellations Draco, Cygnus and Cepheus. The comet is retreating into the distant, cold reaches of the Solar System. If you can, try to observe this infrequent visitor. An hour to ninety minutes before sunrise is an ideal time. Just look high in the northeast, bring binoculars if your have them.

If you follow the constellation Leo's tail to the southeast, you come across a hazy patch of stars, the Constellation Coma Berenices. This is a most unusual constellation. Unlike most, this constellation celebrates a real person and a true love story. Berenices was a princess in ancient Cyrene, modern Libya, in the Third Century BC. She married Ptolemy III, who ruled Egypt. After the wedding, Ptolemy had to lead armies to assist his nephew, another ruler. Like all wives, Berenice worried about her husband in battle. To insure his safe return, Berenice vowed to donate her beautiful hair to the goddess Aphrodite. Upon his return, Berenice fulfilled her vow. The royal couple later asked the court astrologer what happened to the hair. The priest pointed to the hazy patch of stars. Berenice is the great grandmother of another famous female - Cleopatra. Her name lives on even today. The Libyan town of Benghazi is named in her honor.

Tuesday, April 30th. Written by Jonathan Cassidy.

The full moon occurred on April 27 and already the moon is rising after midnight. The winter circle of stars is now setting at dusk and the summer triangle is yet to appear. The big dipper is prominent in the north tonight. The "big dipper" is an asterism or picture we make of stars in the sky. This is different from constellations that have mythology associated with them. The big dipper is part of URSA Major the Bear.

The stars that make up the big dipper have not always looked as they do tonight. The stars at the opposite ends are moving in roughly the same direction but all the stars between are moving in a much different directions. In 100,000 years you will not recognize the asterism we call the big dipper. Instead there will be a dipper approximatly reversed from the one we see tonight. The handle will form a bowl and the bowl will become like a handle.

The stars of this asterism are not all in the same area of our galaxy. The star Alioth is about 70 light years away. Five others are part of a true cluster about 80 light years. Dubhe is just beyond at about 105 light years and Alkaid at the end of the handle is 210 light years away. This is over twice the distance of the next furthest out. Yet they are all still in our home galaxy the Milky Way.

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