The Dudley Observatory

This is a great week for observing Solar System objects, the two most obvious of which are the Sun and the Moon. The Sun continues to climb higher in the south at noon as it approaches its highest point of the year at the summer solstice on June 21. The Moon is full tomorrow (Thursday night), and being the second full Moon this month ( the first having appeared on May 2 ), it is popularly known as a "Blue Moon". Technically, when the Moon becomes full about 9 p.m. on Thursday, it will already be early morning on June 1 in Europe, so they will experience 2 full Moons in June rather than in May.

The next Solar System objects are the five "bright" or naked eye planets, all of which can be seen this week. Venus, the next brightest object after the Sun and Moon, continues to dominate the western sky after sunset with its eye-burning magnitude of minus 4.2. Typically, when Venus puts in a brilliant apparition of the present kind, police stations and military bases receive increased numbers of reports of an Unidentified Flying Object "much brighter than a star". Although Venus is easily identifiable, the description is correct since Venus shines about 30 times brighter than Sirius, the brightest star.

Well below, and to the right of Venus, low in the west-northwest, you can find Venus' fainter, innermost sibling, Mercury, as the twilight fades. Mercury is now at its greatest easternmost distance from the Sun and easiest to see, but look soon because it will begin to drop back toward the Sun and will be lost in the Sun's glare in a couple of weeks.

Above and to the left of Venus shines the ringed planet, Saturn, still close to the bright star, Regulus, in the constellation Leo. Saturn is especially beautiful in a telescope at this time because the Sun's angle casts a shadow of the planet on its rings, giving Saturn a distinct, three-dimensional appearance. Watch Venus' eastward motion bring it closer to Saturn through the month of June, ending on June 30 with a spectacular close pairing of the two planets.

The giant planet, Jupiter, which contains twice the mass of all the other planets combined, is near opposition, rising in the southeast shortly after sunset. After Venus sets, Jupiter dominates the southern sky with its white brilliance. It currently shows a disk size of about 46 arc-seconds, near the maximum possible, and providing an excellent telescopic view of the elegant cloud bands in its atmosphere.

The Red Planet, Mars, rises about 3 a.m. in the faint constellation Pisces, with the brightness of a first magnitude star. It is still too far away for useful observation, but Earth will approach Mars all through his year, until it reaches its nearest approach just before Christmas, when Mars will shine as brightly as Sirius and present a large disk for viewing.

A final, pleasant surprise is the large asteroid, Vesta, which reaches opposition tonight (Wednesday). Vesta is the third largest and second most massive asteroid known, with a diameter of about 333 miles. By a happy coincidence, Vesta reaches its closest approach to Earth within a few days of perihelion, its closest approach to the Sun in its elliptical orbit. This brings Vesta exceptionally close to Earth, and because the surface of Vesta is unusually reflective for an asteroid, about 26% compared to a typical 4%, it will reflect enough sunlight to become visible to the unaided eye, with a magnitude of 5.5. Vesta can be found about 10 degrees north of Jupiter for the next few nights. A precise star map of Vesta' s path can be found in the June issue of Sky and Telescope magazine. Although it is readily visible in binoculars, it might be worth joining the small group of people who can claim to have seen an asteroid with their unaided eyes. Because the Full Moon will be flooding the early night sky with light for the next few nights, you might be more successful if you wait until Monday or Tuesday when the Moon rises later, providing a dark sky for this challenging naked-eye target.

This is the Skywatch Line for Monday and Tuesday, May 28 and 29.
by Joe Slomka

The Sun sets at 8:23 PM, with night falling at 10:32. Dawn breaks at 3:13 AM and ends with sunrise at 5:22.

As the Sun sets, the thirteen-day-old Moon rises from the East, and remains up for most of the night. Saturn rides high in southwestern sky, between Cancer and Leo. Venus is moderately low in the West near Gemini. If you have been following Saturn and Venus, you will have noticed that they are slowly closing, leading to a spectacular conjunction on June 30.

Elusive Mercury can be found to Venus’ lower right. It appears as a small “star” near the feet of Gemini. As the night deepens, Mercury can be found, in binoculars, close to the star cluster M-35. However, at that point trees or hills may hide both.

By the end of twilight, Scorpius rises along with the planet Jupiter and the asteroid Vesta. Jupiter is visible regardless of the Moon’s brightness. However, Jupiter is best seen in pre-dawn hours, when it is higher. Binoculars easily show its four famous moons.
The asteroid Vesta is nine degrees to Jupiter upper right. Vesta is currently about fifth magnitude, visible to the unaided eye in rural areas. Binoculars may help in suburban skies.

In the hours before sunrise, Jupiter prepares to set, but Mars rises. Mars is the brightest object in eastern skies and easy to identify; its distinctive rust color gives it away.

Tonight the Moon is quite visible in our sky. Earth has only one moon, while other planets have many; in fact, there are over 150 moons in our solar system. Only Mercury and Venus are without satellites. Most moons orbit their planets in the same direction as the planet’s spin. This points to a common origin with the planet. Some moons are different. Our Moon is believed to be born of a catastrophic collision of Earth and another body. The Earth-Moon system can almost be called a double planet, since the Moon is so large. Most satellite systems are a fraction of their parent planets.

Clear Skies

Joe Slomka

This is Dudley Observatory's Skywatch Line for Friday, May 25, thru Sunday,
May 27, written by Alan French.

The Sun sets at 8:22 PM and the last vestiges of twilight are completely
gone from the western sky by 10:30. The Moon was at first quarter on
Wednesday, and will be full late next Thursday, so a bright gibbous Moon
will dominate the evening sky.

Mercury is now well into its best appearance of the year in the evening sky,
and is visible low in the west-northwest just after sunset. This writer saw
the innermost planet Thursday night at 8:50 PM. The skies were clear down
to my horizon, and it was fairly easy to see Mercury with the unaided eye.
It was picked up about 10 minutes earlier – at 8:40 – with the help of
binoculars. Unfortunately, the land rises to my west, and it soon vanished
behind my horizon. People with a better view to the west will have an
easier time seeing Mercury a little later in the evening when the western
sky is darker.

To see Mercury, you'll need a good view to the west-northwest, and you'll
want to look between about 9:00 PM and 9:30 PM. At 9:00, Mercury will be a
bit over 11 degrees above the horizon on Friday, rising to 12 degrees on
Sunday. If the sky is nice and clear, it should be easy to spot with your
eye alone. By 9:30 PM, the sun-scorched planet will be only 7 degrees above
the horizon. To gauge distances, hold your fist at arm's length. It will
span 10 degrees across the knuckles.

As a reference, Mercury is about 23 degrees to the lower right of brilliant
Venus. If you imagine Venus to be the center of a clock, Mercury will be
between four and five o'clock. If you cannot see Mercury with your eye
alone, try scanning along the horizon with binoculars.

The waxing gibbous Moon will be passing below the constellation Virgo, the
Virgin, over the weekend. As darkness falls on Sunday night the Moon will
be just over two degrees from Spica, the brightest star in Virgo. Spica
will be above and to the left of the Moon, just over two degrees away.
Spica is actually two stars orbiting very close together. They are
separated by about one third the distance between our Sun and Mercury, and
orbit about each other once every four days.

This is the Skywatch Line for Monday and Tuesday, May 21 and 22.
by Joe Slomka

The Sun sets at 8:17 PM, with night falling at 10:22. Dawn breaks at 3:22 AM, ending with sunrise at 5:26.

At sunset, Venus blazes high in the western sky. Venus grows larger in binoculars and telescopes, but becomes a slimmer crescent. Venus is currently about 59 percent illuminated; over the next month it shrinks to a sliver. Mercury emerges well to Venus’ lower right.

Monday night finds the six-day-old Moon parked in Cancer, only a degree from the famous Beehive star cluster. The Moon’s bright crescent will probably hide the cluster’s glory. The next night allows binocular views. Tuesday night situates the Moon two degrees from Saturn. Saturn withstands the bright Moon. A telescope provides views of the Moon’s craters and also of Saturn’s shadow falling on the rings.

Jupiter and Vesta rise at twilight. The hours after midnight are a better time to observe, when they are situated higher. New observers are constantly amazed by Jupiter’s cloud and satellite systems. Jupiter is easily spotted – just above the constellation Scorpius and its heart-star, Antares. The asteroid Vesta is equally high above Jupiter. Vesta is now visible to the naked eye. Simply look for the brightest star to Jupiter’s upper right. Vesta remains at fifth magnitude for May and June, after which it returns to the outer reaches of the Solar System.

Leo is a constellation that resembles its namesake. If one looks past Denebola, the Lion’s Tail, one sees a hazy cloud. Binoculars show it to be a galactic star cluster called Coma Berenices.

Berenice is not mythical figure. She married Ptolemy III of Egypt. When her brother-in-law involved the Pharaoh in a war, Berenice 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 what happened to her donation. He replied by pointing to the hazy cloud and said the gods accepted her sacrifice. Berenice is famous for another reason; she is Cleopatra’s grandmother.

This is Dudley Observatory's Skywatch Line for Friday, May 18, thru Sunday, May 20, written by Alan French.

This weekend provides an excellent chance to spot Venus during the day, and
features a beautiful pairing of Venus and the crescent Moon in the evening
sky.

Brilliant Venus continues to dominate the night sky toward the west during
the hours after sunset. Venus is actually bright enough to see during the
day – the trick is knowing where to look. On Saturday afternoon, the Moon
will provide a nice landmark to help you find Venus in the daytime sky.

The best time to look for the Moon and Venus on Saturday will be 3:50 PM,
when the pair is due south and highest in the sky. When objects are high in
the sky you are looking through less of our atmosphere, and they are
somewhat brighter and easier to see. This is a valuable advantage when
looking for Venus during the day.

First, look for the Moon very high in the south. It is high enough that it
will appear almost overhead. Once you've found the Moon, look for Venus to
the Moon's lower left. If you are facing south, and you imagine the Moon as
the center of a clock, Venus will be in the 8 o'clock position. The pair
will be a little over three degrees apart. As a reference, keep in mind
that the Moon itself spans one half a degree. Your hand can also be a good
measure of angular distances in the sky. If you hold your little finger at
arm's length, it spans one degree. Your first three fingers held together
at arm's length span five degrees.

If you have trouble spotting the point of light that is Venus, try looking
back at the Moon and then try for Venus again. When staring at the blue sky
our eyes have nothing to focus on, and may not be focused well enough to
spot Venus. Try returning your gaze to the Moon a few times if necessary.

If you are unable to spot Venus near the Moon by eye alone, try seeing it
with binoculars. Carefully focus them on the Moon, and then place the Moon
at about the two o'clock position in your binoculars. Venus should appear
as a point of light near the center or a bit below and left of center. Once
you've located it in binoculars, try again with your eye alone.

As the Sun sets at 8:15 Saturday the Moon and Venus will begin brightening,
and it will be easier to spot Venus. By the time the sky is growing dark,
Venus and the crescent Moon will be a beautiful sight in the western sky.
Because of the Moon's eastward motion among the stars, they will be even
closer together than they were at 3:50 PM – separated by less than two
degrees. A beautiful sight!

You can also use the Moon as a guide to finding Venus on Sunday afternoon,
although the pair with be farther apart. At 3:50 PM, Venus will be 10
degrees away from the Moon. If you are facing south, Venus will be almost
directly to the Moon's right. If you held a fist at arm's length, it spans
10 degrees.

On Saturday, the Albany Area Amateur Astronomers will host a public star
party in Glenville's Indian Meadows Park beginning at 9:00 PM. The park is
on the west side of Droms Road, which runs between Swaggertown and Charlton
Road. The park entrance is about 1/2 mile south of the Parkside YMCA and is
marked by a large wooden sign. After passing the park buildings on your
right, bear right at the next fork in the road. Telescopes will be aimed at
ringed Saturn and the crescent Moon, and other celestial wonders. Guests of
all ages are always welcome at star parties and there is no charge. The
star party is cancelled if the skies are mostly cloudy. If in doubt, call
374-8460 after 6:00 PM Saturday.

This is Dudley Observatory's Skywatch Line for Wednesday and Thursday, May
16 and 17, written by Alan French.

The Sun now sets just before 8:15 PM and the last traces of twilight are
gone by 10:15. Under dark, rural skies traces of dawn may be seen in the
eastern sky before 4:00 AM. The Sun rises just after 5:15.

The Moon is new Wednesday afternoon, so the skies will be dark and moonless
on Wednesday and Thursday nights, although a very thin crescent Moon will be
visible just after sunset on Thursday. The crescent will be very close to
the planet Mercury, and the pair will make a pretty sight if you look at the
right time and are fortunate enough to have clear skies.

Seeing Mercury and the Moon Thursday night requires a good view to the
west-northwest. You'll need a low, flat horizon clear of tall trees and
buildings, and skies free of haze and clouds. You'll also want to look at
9:10 PM, when the sky is reasonably dark, but Mercury and the Moon are still
above the horizon.

The slender crescent Moon will be 10 degrees above the north northwestern
horizon. (As a reference, keep in mind that a fist held at arm's length
spans 10 degrees.) Mercury will be just to the lower left of the Moon, with
a little less than three degrees between the pair. With clear skies, they
should be fairly easy to spot, although haze or low clouds can make it
difficult. If you have trouble spotting them with your eye alone, try
scanning along the horizon with binoculars. Even if you find them without
resorting to binoculars, the pair will be a very pretty sight in binoculars.

Venus continues to dominate the night sky toward the west during the hours
after sunset. Venus is actually bright enough to see during the day – if
you know where to look. On this weekend's Skywatch Line, we'll tell you how
to find Venus during the day on Saturday, and tell you about a beautiful
sight in the evening sky on Saturday.

This coming Saturday, the Albany Area Amateur Astronomers will host a public
star party in Glenville's Indian Meadows Park beginning at 8:30 PM. The
park is on the west side of Droms Road, which runs between Swaggertown and
Charlton Road. The park entrance is about 1/2 mile south of the Parkside
YMCA and is marked by a large wooden sign. After passing the park buildings
on your right, bear right at the next fork in the road. Telescopes will be
aimed at ringed Saturn and the crescent Moon, and other celestial wonders.
Guests of all ages are always welcome at star parties and there is no
charge. The star party is cancelled if the skies are mostly cloudy. If in
doubt, call 374-8460 after 6:00 PM Saturday.

This is the Skywatch Line for Monday and Tuesday, May 14 and 15.
by Joe Slomka

The Sun sets at 8:10 PM with night falling two hours later. Dawn breaks at 3:34 AM and ends with sunrise also two hours later.

Shortly after sunset, Venus pops into view. Venus is so bright that it is actually easier to observe during twilight than at night. In strong binoculars or telescope, Venus appears about sixty percent illuminated. In coming weeks Venus becomes brighter, but also a thinner crescent. This is a result of Venus’ orbit between Earth and Sun. Dimmer Mercury joins Venus some time later. Mercury appears very low to Venus’ right. Trees or hills may hide it. If so, wait a few days; Mercury will become easier to find and observe. Mercury too displays phases; it is now about 83 percent illuminated.

Saturn is next to appear, high in the southwest. If you observe Saturn in a telescope, you will see its shadow falling on the famous ring system – a sight not to miss! Saturn slowly closes in on Venus over the coming month. On June 30, Saturn and Venus will appear less than a degree apart. See if you can track their approach.

By the end of twilight, Venus and Mercury are gone; Saturn remains low in West. Jupiter rises about the same time, but too low for useful observation. Jupiter is best observed shortly before daybreak, when it is better placed. Also visible is the asteroid 4 Vesta. Vesta was the fourth asteroid to be discovered. It is temporarily about fifth magnitude, which means that it should be naked eye visible in rural skies. It is found about eight degrees above Jupiter. Astronomy magazines and some websites provide detailed charts to assist in your hunt.

Astronomy is a great hobby and easy to begin. However, the beginner is frequently bombarded with unusual terms and advertising hype. The Albany Area Amateur Astronomers have their monthly meeting on Tuesday, May 15 at 7:30 PM at the Schenectady Museum and Planetarium. This meeting will feature a panel of experts who will answer questions from the audience. All club events are free and open to the public. Visitors are very welcome.

Clear Skies

Joe Slomka

This is Dudley Observatory's Skywatch Line for Friday, May 11, through Sunday, May 13, written by Alan French.

The Moon will be new this coming Wednesday, so the skies over the weekend
will be dark and moonless until the hours just before sunrise. The Moon
will not emerge into the eastern sky until after 3:00 AM – making this a
great weekend for stargazers.

Elusive Mercury, the innermost planet, is emerging into the evening sky and
may be spotted briefly just after sunset. Because Mercury orbits close to
the Sun, it never appears high in the sky, and is only seen briefly just
after sunset or just before sunrise. Many people have never seen Mercury.
You'll need good horizons and clear skies to the west-northwest to spot
Mercury.

The Sun sets around 8:08 PM this weekend, and you'll want to look for
Mercury at 8:45. Mercury will be just under four degrees above the west
northwestern horizon. If you look at brilliant Venus higher in the west and
imagine Venus marking the center of a clock, Mercury would be between the
four and five o'clock position and just above the horizon. If Mercury is
not visible to your eye alone, scan the horizon with binoculars to locate
the elusive planet. If you miss Mercury or the skies were uncooperative,
don't despair – it will be moving higher and getting easier to spot.

Weather permitting; the Albany Area Amateur Astronomers will host two public
star parties this weekend. At Star Parties a variety of telescopes are
pointed at celestial objects for your enjoyment. Saturn and its beautiful
rings will be one highlight of these star parties.

Friday night's star party will be held at Landis Arboretum in Esperance
beginning at 9:30 PM. Entering Esperance from the east on Route 20, take
the first right after crossing Schoharie Creek. There is a large "George
Landis Arboretum" sign at this intersection. Follow the signs for 1.5 miles
until you reach the arboretum, and then continue up Lape Road past the main
parking area on your left and farmhouse on your right. At the top of the
small hill, turn right into the Meeting House drive. The star party will be
held in the field by the Meeting House.

Saturday night's star party will be held at Deerfield Pavilion in Grafton
Lakes State Park beginning at 7:30 PM. Contact Bernard at 658-9144 or Dave
at 274-0947 for directions or further information.

Star parties are cancelled if the skies are mostly cloudy. If in doubt,
call 374-8460 about Friday's star party at Landis Arboretum, and call
658-9144 or 274-0947 about the Saturday night star party in Grafton Lakes
State Park.

The Albany Area Amateur Astronomers will hold their monthly meeting at 7:30
PM on Tuesday night, April 15, at the Schenectady Museum. At the meeting, a
"Panel of Experts" will be answering questions about amateur astronomy and
telescopes. The meeting is free and open to all ages.

With Jupiter now rising about 10:30 p.m., it is possible to see three bright planets in the sky together about 11:00 p.m., with Jupiter rising low in the east, Saturn high in the west and Venus preparing to set low in the west. The Earth is in the process of overtaking and passing Jupiter early next month, when the gas giant will stand at opposition and appear as large and bright as it ever gets. Its low position in the southern sky will afford southern observers a somewhat better view than we will have from our northern latitude. We are currently receding from Saturn so that it will diminish somewhat in size and brightness over the course of this month. However, the angle of the Sun's light on Saturn will cast an observable shadow of the disk on Saturn's rings, giving it a wonderful three-dimensional appearance. Venus is approaching us, so its size and brightness will slowly increase through this month.

In a couple of weeks, this trio will be joined by Mercury which is even now emerging into the western sky after passing behind the Sun a week ago. In two weeks, Mercury will be setting almost two hours after the Sun and after Jupiter has risen, so all four planets will be visible at one time.

A special opportunity presents itself this month when the asteroid Vesta, approaching opposition at the end of May, becomes bright enough to be visible to the unaided eye. Vesta is the second largest "dwarf planet" with a diameter of about 325 miles and an unusually light, reflective surface. This season's apparition of Vesta is especially bright because it will be closest to Earth, at opposition, on May 30th within a couple of weeks of perihelion, its closest approach to the Sun when it will be more brightly lit than usual. Vesta is currently shining at magnitude 5.8 and will slowly increase to its brightest magnitude, 5.4, by the end of this month. It will will be easiest to find Vesta a few degrees above ( north of ) bright Jupiter in Ophiucus during the dark, Moonless period from now to about May 20. An excellent article describing the circumstances and path of Vesta this season, including a detailed sky map, can be found in the June issue of Sky and Telescope on page 57. Not many people can claim to have seen an asteroid with their unaided eyes, so finding Vesta will be a real feather in your astronomical cap. Don't hesitate to use binoculars to improve your view once you have found it. Happy hunting!

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

The Sun sets shortly after 8 PM, with night falling about 10 PM. Dawn breaks at 3:45 AM, ending with sunrise at 5:40.

At Sunset, two bright planets attract attention. Venus is brightest, high in the western sky. In powerful binoculars or telescope, Venus is about two-thirds illuminated. Venus is very high in the sky; it sets shortly before midnight. In a few days, it will be at its highest.

Saturn is next to be seen, high in southern nights. Saturn lies midway between Leo and Cancer. Its creamy color identifies it as a planet. Telescope observers can see the giant planet’s shadow falling across the rings. Saturn and Venus are gradually coming closer; a conjunction takes place in July.

Midnight finds Jupiter joining Saturn. Jupiter blazes near the obvious constellation Scorpius and its brightest star, Antares. Both Jupiter and Saturn are giant balls of gas. Jupiter and Saturn both have ring systems, but Jupiter’s is so faint that only space probes revealed their existence. Jupiter also guides us to the asteroid Vesta, about eight and a half degrees above the planet. Vesta is a rock about 500 kilometers in diameter. Most asteroids are dim and difficult to see. Vesta, now, is visible to naked eye observers in rural skies. Most star charts now show Vesta’s position since its promotion to “minor planet.” Charts are necessary because Vesta is located in the star filled Milky Way.

Most of the constellations and planets came to us through the Mesopotamians, who were expert astronomers and astrologers. Jupiter is an example. Mesopotamian legends tell of a fierce war between clans of gods. Marduk led one clan, conquered his opponents, founded the Earth, as we know it, and established Babylon as the center of the world. The planet we know as Jupiter was his “star.” Many scientists believe that Earth could not exist without Jupiter. Jupiter acts as a gigantic “magnet,” attracting comets and asteroids that would otherwise threaten the development of life on Earth; an example is 1994’s Comet Shoemaker-Levy 9, which crashed onto Jupiter.

Clear Skies

Joe Slomka

This is the Skywatch Line for Monday and Tuesday, April 30 and May First.
by Joe Slomka

The Sun sets at 7:55 PM; night falls at 9:45. Dawn breaks at 4:00 AM, and ends with sunrise at 5:50.

As the Sun sets Venus continues to blaze in the western sky, although a bit lower. Venus is gradually becoming brighter and larger in your telescope, but a thinner crescent.

Saturn lies due south at Sunset, still hovering between Leo and Cancer. After nightfall, this is an ideal time to observe Saturn. Saturn is positioned between Earth and Sun so that its shadow falls on the rings. This lends a 3D effect to one of the most popular objects at any star party.

The Moon appears at Sunset also. It is low in the southeast, just below the bright star Spica in Virgo. Monday night’s Moon is nearly full; Tuesday finds a Full Moon midway between Virgo and Libra.

By midnight, Venus has set, but Jupiter has risen, low in the East. Jupiter will be ideal for observation for the rest of the night. Internet reports are that its cloud systems are becoming active. Telescope users can follow the progress of these changes.

Two new objects accompany Jupiter. Comet Lovejoy briefly graced our skies in late winter and early spring. The Comet now returns and is found near the constellation Lyra, with its bright star Vega. Over the next few nights, the comet travels along side of Lyra until it is astride Vega on Wednesday. Binoculars should help in finding the comet. The asteroid Vesta appears eight degrees above Jupiter, in the constellation Ophiuchus. Vesta can be seen with the naked eye from rural skies. Binoculars will help finding it from Capital District skies. Unlike Comet Lovejoy, Vesta plods along and does not make dramatic changes in position. Most astronomy magazines and websites show Vesta’s position.

Comets and asteroids are both members of the Solar System. Comets are ice and rock mixtures; the tail is actually evaporated ice. Asteroids are mostly rock and do not sport tails. Both orbit the Sun in predictable paths.