New- Star Chart For Cayman


20 December 2009, 6.30 p.m.

We will meet on Sunday, 20th 6.30 p.m. at the end of Windward Street in North Sound Estates.

On 16 December 2009, the European Space Agency (ESA) reported that the Herschel Space Observatory has peered inside an unseen stellar nursery and revealed surprising amounts of activity. Some 700 newly-forming stars are estimated to be crowded into filaments of dust stretching through the image.



Gould’s Belt supplies bright stars to many constellations such as Orion, Scorpius, Canis Major, Puppis, Carina, Centaurus, and Crux, and conveniently provides nearby star-forming locations for astronomers to study. Observing these stellar nurseries is a key programme for Herschel, which aims to uncover the demographics of star formation and its origin, or in other words, the quantities of stars that can form and the range of masses that such newborn stars can possess. Apart from this region of Aquila, Herschel will target 14 other star-forming regions as part of the Gould’s Belt Key Programme.

More recent observations have established that the Gould Belt is a key structural feature of the Orion Arm, the region of the Milky Way Galaxy in which we live. It is an elliptical disk of hydrogen and other gases, inclined to the plane of the larger Galactic disk by an angle of about 17.2 degrees. Its long axis is about 750 parsecs, and its short axis is about 470 parsecs. Its age is estimated as 30 to 50 million years. In astronomical terms, therefore, the Gould Belt is a very young formation -- much more recent, for example, than the Jurassic Period (145-200 million years ago), when large dinosaurs roamed the Earth.


The second full moon of December will fall on New Years Eve, a big, bright Blue Moon. A blue moon is a full moon that is not timed to the regular monthly pattern. Most years have twelve full moons which occur approximately monthly, but in addition to those twelve full lunar cycles, each calendar year contains an excess of roughly eleven days. The extra days accumulate, so that every two or three years (on average about every 2.7154 years), there is an extra full moon.

Thursday, 19th November, 6.30. p.m Pedros Castle

The meeting will be very dependent on the Weather - meeting will be cancelled if greater than 50 percent cloud cover. If in doubt on the Weather at Pedros ring Nick Kelly on 9473065
However lets be optimistic.

When darkness falls, on the 19th, the sky will look like the diagram above.
In the south, shines one of the brightest stars in the sky, Fomalhaut, brightest star in the constellation Piscis Austrinus.
Piscis Austrinus (also known as Piscis Australis) is a constellation in the southern celestial hemisphere. The name is Latin for "the southern fish" in contrast with the larger constellation Pisces, which represents a pair of fishes.

Fomalhaut means "mouth of the whale", from the Arabic. It is a class A star on the main sequence approximately 25 light-years from Earth. It is classified as a Vega-like star that emits excess infrared radiation, indicating it is surrounded by a circumstellar disk.
Fomalhaut holds a special significance in extrasolar planet research, as it is the center of the first stellar system with an extrasolar planet (Fomalhaut b) imaged at visible wavelengths. The image was published in Science in November 2008.[2]
Fomalhaut is believed to be a young star, only 100 to 300 million years old, with a potential lifespan of a billion years. The surface temperature of the star is around 8,751 K (15,292 °F; 8,478 °C). Compared to the Sun, its mass is about 2.1, its luminosity is about 18, and its diameter is roughly 1.8. Fomalhaut has a slightly lower proportion of elements with higher atomic numbers than helium: about 79% as much as the Sun.
Fomalhaut is a member of the 16 stars belonging to the Castor Moving Group. This is an association of stars that shares a common motion through space and are therefore likely to be physically associated. Other members of this group include Castor and Vega. This moving group has an estimated age of 200 ± 100 million years and originated from the same location. The nearby star TW Piscis Austrini, a member of this group, may form a physical pair with Fomalhaut.
On November 13, 2008, astronomers announced the discovery of an extrasolar planet orbiting just inside the debris ring. This was the first extrasolar planet to be seen with visible light, captured by the Hubble Space Telescope. The planet's existence had been previously suspected from the sharp, elliptical inner edge of Fomalhaut's debris disk. The mass of the planet, Fomalhaut b, is estimated to be no more than three times the mass of Jupiter and at least the mass of Neptune.

21st October 2009, 6.30 at Pedro Castle

In Capricornus, the planet Jupiter outshines all the faint stars in what is the second faintest constellation in the zodiac after Cancer.

The illustration above is approximate size comparison of Earth and Jupiter, including the Great Red Spot. The Great Red Spot, a persistent anticyclonic storm located 22° south of the equator is larger than Earth. It is known to have been in existence since at least 1831, and possibly since 1665. Mathematical models suggest that the storm is stable and may be a permanent feature of the planet. The storm is large enough to be visible through Earth-based telescopes with an aperture of 12 cm or larger.



The planet was known by astronomers of ancient times and was associated with the mythology and religious beliefs of many cultures. The Romans named the planet after the Roman god Jupiter. When viewed from Earth, Jupiter can reach an apparent magnitude of −2.8, making it on average the third-brightest object in the night sky after the Moon and Venus. (Mars can briefly exceed Jupiter's brightness at certain points in its orbit.)




A 1997 survey of historical astronomical drawings suggested that the astronomer Cassini may have recorded an impact scar in 1690. During the period July 16, 1994 to July 22, 1994, over 20 fragments from the comet Shoemaker-Levy 9 collided with Jupiter's southern hemisphere, providing the first direct observation of a collision between two Solar System objects. This impact provided useful data on the composition of Jupiter's atmosphere.

On July 19, 2009, an impact site was discovered at approximately 216 degrees longitude in System 2. This impact left behind a black spot in Jupiter's atmosphere, similar in size to Oval BA. Infrared observation showed a bright spot where the impact took place, meaning the impact warmed up the lower atmosphere in the area near Jupiter's south pole.

Pedro Castle,2009, September 21st, 7.00 p.m.

The summer was literally a washout for observing,but we're back.

The diagram above shows the night sky at viewing time. Jupiter is brilliant in the south-east. Further to the north can be found the constellation Lyra which is easily identified by using the bright star Vega, which is one of the brightest in the sky.

In Lyra, the name of which is derived from the lyre, a stringed musical instrument well known for its use in classical antiquity and later, can be found M56, a rather loose globular cluster at a distance of approximately 32,900 light-years, with a diameter of about 85 light years.


Globular clusters, which are found in the halo of a galaxy, contain considerably more stars and are much older than the less dense galactic, or open clusters, which are found in the disk. Globular clusters are fairly common; there are about 158 currently known globular clusters in the Milky Way, with perhaps 10 to 20 more still undiscovered. Large galaxies can have more: Andromeda, for instance, may have as many as 500. Some giant elliptical galaxies, such as M87, may have as many as 10,000 globular clusters. These globular clusters orbit the galaxy out to large radii, 40 kilo parsecs (approximately 131,000 light-years) or more.


The first globular cluster discovered was M22 in 1665 by Abraham Ihle, a German amateur astronomer. However, given the small aperture of early telescopes, individual stars within a globular cluster were not resolved until Charles Messier observed M4

Beginning in 1914, Harlow Shapley began a series of studies of

globular clusters, published in about 40 scientific papers. He examined the cepheid variables in the clusters and would use their period–luminosity relationship for distance estimates.

Of the globular clusters within our Milky Way, the majorities are found in the vicinity of the galactic core, and the large majorities lie on the side of the celestial sky centered on the core.

In 1918 this strongly asymmetrical distribution was used by Harlow Shapley to make a determination of the overall dimensions of the galaxy. By assuming a roughly spherical distribution of globular clusters around the galaxy's center, he used the positions of the clusters to estimate the position of the sun relative to the galactic center. While his distance estimate was significantly in error, it did demonstrate that the dimensions of the galaxy were much greater than had been previously thought. His error was due to the fact that dust in the Milky Way diminished the amount of light from a globular cluster that reached the earth, thus making it appear farther away. Shapley's estimate was, however, within the same order of magnitude of the currently accepted value.



Globular clusters are generally composed of hundreds of thousands of low-metal, old stars. The types of stars found in a globular cluster are similar to those in the bulge of a spiral galaxy but confined to a volume of only a few cubic parsecs. They are free of gas and dust and it is presumed that all of the gas and dust was long ago turned into stars.

While globular clusters can contain a high density of stars (on average about 0.4 stars per cubic parsec, increasing to 100 or 1000 stars per cubic parsec in the core of the cluster),[14] they are not thought to be favorable locations for the survival of planetary systems. Planetary orbits are dynamically unstable within the cores of dense clusters because of the perturbations of passing stars. A planet orbiting at 1 astronomical unit around a star that is within the core of a dense cluster such as 47 Tucanae would only survive on the order of 108 years



Hopefully we will have some clear skies and be able to see some of these ancient star groups.

Pedro Castle, June 25th. 7.30 p.m. 2009

Close to the zenith and easily identifiable is the bright star Spica, which is the alpha star in the constellation Virgo.
Virgo is one of the constellations of the zodiac. Its name is Latin for virgin,). Lying between Leo to the west and Libra to the east, it is the second largest constellation in the sky.
Because of the presence of a galaxy cluster (consequently called the Virgo cluster) within its borders), this constellation is especially rich in galaxies.
Spica (also known as α Vir / α Virginis / Alpha Virginis) is the 15th brightest star in the nighttime sky. It is 260 light years distant from Earth. A blue giant, it is a variable of the Beta Cephei type.

Who exactly Virgo was considered to represent is uncertain; in history, it has been associated with nearly every prominent goddess, including Ishtar, Isis, Cybele, and Athena, as well as with Mary the Mother of Jesus.
Saturn is visible as darkness falls, but for the other planets you will either stay up late, to see Jupiter, which rises after 10 pm, or get up before dawn to see Venus and Mars.

Pedro Castle,May 27th, 2009, 7.30 p.m.

In the rainy season the decision whether or not to view is determined by the amount of cloud cover. If more than 50% of the sky is obscured, we cancel. This can sometimes be a difficult judgment call.
The constellation illustrated above is Leo, the Lion, which is visible overhead as darkness falls. The sickle shape, or backwards question mark with the bright star Regulus at its base, is easy to discern.
Brighter Saturn is below the question mark.
Regulus, which means the heart of the lion, is a hot, blue star which has a luminosity about 140 times that of the Sun and about 3.4 times the diameter. The star is in fact the A component of a multiple star system. The B and C components are a close binary pair revolving together about 100 AU (Astronomical Unit) from the A star. This is two and a half time the distance of Pluto and the Sun.
The Sumerians are recorded as seeing this group of stars as a lion. The form of the Lion was probably passed along to the Babylonians, Greeks, Roman and others. The Egyptians worshipped the lion because the sun was in this constellation at the time of the life-giving floods of the Nile.
In Greek mythology, it was identified as the Nemean Lion which was killed by Herakles during one of his twelve labours, and subsequently put into the sky by the goddess Hera, the vengeful wife of his father, Zeus.

Pedro Castle,April 28th, 7.00 p.m.

The zenith at 7 on Tuesday will be just across the boundary line separating Gemini from Cancer, the constellation illustrated above.
Cancer is famous despite itself due to its Zodiacal origins. In fact, it is very faint with no stars brighter than 4th magnitude. However, it is home to Praesepe (M44), an open cluster also called the Beehive Cluster or the Gate of Men. In the picture above, it is the star marked next to the lower eyestalk. It is one of the nearest open clusters to the Solar System, and it contains a larger star population than most other nearby clusters. Under dark skies the Beehive Cluster looks like a nebulous object to the naked eye; thus it has been known since ancient times.

Like many star clusters of all kinds, Praesepe has experienced mass segregation. This means that bright, massive stars are concentrated in the cluster's core, while dimmer, less massive stars populate its halo (sometimes called the "corona"). The cluster's core radius is estimated at 3.5 parsecs (11.4 light years); its half-mass radius is about 3.9 parsecs (12.7 light years); and its tidal radius is about 12 parsecs (39 light years). However, the tidal radius also includes many stars that are merely "passing through" and not bona fide cluster members.
Altogether, the Praesepe cluster contains at least 1000 gravitationally bound stars, for a total mass of about 500-600 Solar masses. A recent survey counts 1010 high-probability members, of which 68% are M dwarfs, 30% are Sun-like stars of spectral classes F, G, and K, and about 2% are bright stars of spectral class A. Also present are five giant stars, four of which have spectral class K0 III and the fifth G0 III.
So far, eleven white dwarfs have been identified, representing the final evolutionary phase of the cluster's most massive stars, which originally belonged to spectral type B. Brown dwarfs, however, are extremely rare in this cluster, probably because they have been lost by tidal stripping from the halo.
Galileo was one of the first to study this open cluster with optical aid and counted forty stars.
Praesepe is Latin meaning crib or manger. Some ancient lore is associated with it: Greeks and Romans saw this "nebula" as the manger (Greek: Phatne) associated with two asses who eat from it, Asellus Borealis, the Northern Ass and Asellus Australis, the Southern Ass. Erathosthenes reported that these were the asses on which the gods Dionysos and Silenus rode into the battle against the Titans, who were frightened by the animals' braying so that the gods won. As a reward, the asses were put in sky together with Phatne.
The wine must have been good in ancient Greece.
Aratos (260 B.C.) mentioned this object as "Little Mist", Hipparchus (130 B.C.) included this object in his star catalog and called it "Little Cloud" or "Cloudy Star." Ptolemy, the Roman[1] mathematician, astronomer, geographer and astrologer mentions it as one of seven "nebulae" he noted in his Almagest.
According to the new determination by ESA's astrometric satellite Hipparcos, the cluster is 577 light years distant (previous estimates have been at 522 light years), and its age was estimated at about 730 million years.
Open clusters are physically related groups of stars held together by mutual gravitational attraction. Therefore, they populate a limited region of space, typically much smaller than their distance from us, so that they are all roughly at the same distance. They are believed to originate from large cosmic gas and dust clouds (diffuse nebulae) in the Milky Way, and to continue to orbit the galaxy through the disk. In many clouds visible as bright diffuse nebulae, star formation still takes place at this moment, so that we can observe the formation of new young star clusters. The process of formation takes only a considerably short time compared to the lifetime of the cluster, so that all member stars are of similar age. Also, as all the stars in a cluster formed from the same diffuse nebula, they are all of similar initial chemical composition.
Saturn is in the constellation Leo, shining in bright competition with Regulus.

Pedro Castle, March 29th, 7.00 p.m.

The Pleiades, known as the Seven Sisters, will be close to the crescent Moon on the 29th March . This is a nearby, fairly loose open cluster of about 500 stars in the constellation Taurus. Although it is also known as the Seven Sisters, most people can see only six stars, all of them bright blue-white B or Be stars: Alcyone, Atlas, Electra, Maia, Merope, and Taygeta (Pleione is the seventh brightest).
Saturn is risen in the east (magnitude +0.5, near the hind foot of Leo) and is just past opposition. The planet is well up in the southeast by midevening, and highest in the south around midnight. Don't confuse Saturn with slightly fainter Regulus 18° (nearly two fist-widths at arm's length) to its upper right in early evening, and more directly to Saturn's right late at night.
Saturn's rings are 3½° from edge on. The rings will open to 4° by late May, then will close to exactly edge-on next September 4th — when, unfortunately, Saturn will be out of sight practically in conjunction with the Sun.

March 2nd 2009

The revolution of the Moon around the Earth makes the Moon appear as if it is changing shape in the sky. This is caused by the different angles from which we see the bright part of the Moon's surface. These are called "phases" of the Moon. Of course, the Moon doesn't generate any light itself; it just reflects the light of the Sun. The Moon passes through four major shapes during a cycle that repeats itself every 29.5 days. The phases always follow one another in the same order.
Although this cycle is a continuous process, there are eight distinct, traditionally recognized stages, called phases. The phases designate both the degree to which the Moon is illuminated and the geometric appearance of the illuminated part. These phases of the Moon, in the sequence of their occurrence (starting from New Moon), are listed below.
(1) New Moon - When the Moon is roughly in the same direction as the Sun, its illuminated half is facing away from the Earth, and therefore the part that faces us is all dark: we have the new moon. When in this phase, the Moon and the Sun rise and set at about the same time. (2) Waxing Crescent Moon - As the Moon moves around the Earth, we get to see more and more of the illuminated half, and we say the Moon is waxing. At first we get a sliver of it, which grows as days go by. This phase is called the crescent moon. (3) Quarter Moon - A week after the new moon, when the Moon has completed about a quarter of its turn around the Earth, we can see half of the illuminated part; that is, a quarter of the Moon. This is the first quarter phase. (4) Waxing Gibbous Moon - During the next week, we keep seeing more and more of the illuminated part of the Moon, and it is now called waxing gibbous (gibbous means "humped"). (5) Full Moon - Two weeks after the new moon, the moon is now halfway through its revolution, and now the illuminated half coincides with the one facing the Earth, so that we can see a full disk: we have a full moon. As mentioned above, at this time the Moon rises at the time the Sun sets, and it sets when the Sun rises. If the Moon happens to align exactly with the Earth and Sun, then we get a lunar eclipse. (6) Waning Gibbous Moon - From now on, until it becomes new again, the illuminated part of the Moon that we can see decreases, and we say it's waning. The first week after full, it is called waning gibbous. (7) Last Quarter Moon - Three weeks after new, we again can see half of the illuminated part. This is usually called last quarter. (8) Waning Crescent Moon - Finally, during the fourth week, the Moon is reduced to a thin sliver from us, sometimes called waning crescent. A while after four weeks (29.5 days, more precisely) the illuminated half of the Moon again faces away from us, and we come back to the beginning of the cycle: a new moon. Sometimes, when the Moon is almost new, it is possible to dimly see its darkened disk. The light from the Sun cannot reach this part of the Moon directly; but at this time the Earth (as viewed from the Moon) is at its full and very bright, and what we see is light reflected from the Earth, that then bounces back at us from the Moon. It's a long trip for this light: from the Sun to the Earth, to the Moon, and back to the Earth, about 480,000 miles in total.
Venus (visible in the west) is the next closest visible heavenly body, but it is never closer than 25,000,000 miles from the earth. The moon appears to be as large as it is because of its closeness, but it is comparatively small since it is only a quarter of the diameter of the earth.
The sun is a hundred times the diameter of the earth, but it is also about 93,000,000 miles away. It just happens that size and distance cancel each other and both the sun and the moon appear to be the same size. Although the moon is moving from west to east, the earth's spin overtakes it and makes it seem to move from east to west. It appears to "rise" in the east, moves westward, and "sets" in the west.

January 2009, Pedro Castle 7.00 pm

The extremely bright object high in the western sky is the planet Venus.
The planet is named after Venus, the Roman goddess of love. It is the brightest natural object in the night sky, except for the Moon, reaching an apparent magnitude of −4.6. Because Venus is an inferior planet from Earth, it never appears to venture far from the Sun: its elongation reaches a maximum of 47.8°. Venus reaches its maximum brightness shortly before sunrise or shortly after sunset, for which reason it is often called the Morning Star or the Evening Star.
Classified as a terrestrial planet, it is sometimes called Earth's "sister planet," because they are similar in size, gravity, and bulk composition. Venus is covered with an opaque layer of highly reflective clouds of sulfuric acid, preventing its surface from being seen from space in visible light; this was a subject of great speculation until some of its secrets were revealed by planetary science in the twentieth century. Venus has the densest atmosphere of all the terrestrial planets, consisting mostly of carbon dioxide, as it has no carbon cycle to lock carbon back into rocks and surface features, nor organic life to absorb it in biomass. It has become so hot that the earth-like oceans that the young Venus is believed to have possessed have totally evaporated, leaving a dusty dry desertscape with many slab-like rocks. The best hypothesis is that the evaporated water has dissociated, and with the lack of a planetary magnetic field, the hydrogen has been swept into interplanetary space by the solar wind. The atmospheric pressure at the planet's surface is 92 times that of the Earth.
Venus rotates once every 243 days—by far the slowest rotation period of any of the major planets. To an observer on the surface of Venus the time from one sunrise to the next would be 116.75 days.
As the brightest point-like object in the sky, Venus is a commonly misreported 'unidentified flying object'. U.S. President Jimmy Carter reported having seen a UFO in 1969, which later analysis suggested was probably the planet, and countless other people have mistaken Venus for something more exotic.
As it moves around its orbit, Venus displays phases in a telescopic view like those of the Moon: In the phases of Venus the planet presents a small "full" image when it is on the opposite side of the Sun. It shows a larger "quarter phase" when it is at its maximum elongations from the Sun. Venus is at its brightest in the night sky and presents a much larger "thin crescent" in telescopic views as it comes around to the near side between the Earth and the Sun. Venus is at its largest and presents its "new passes" when it is between the Earth and the Sun. Since it has an atmosphere it can be seen in a telescope by the halo of light refracted around the planet.
In the West, before the advent of the telescope, Venus was known as a 'wandering star'.
There is a spacecraft operating in orbit around the planet now. Venus Express probe was designed and built by the European Space Agency. Launched on November 9, 2005 by a Russian Soyuz-Fregat rocket it successfully assumed a polar orbit around Venus on April 11, 2006. The probe is undertaking a detailed study of the Venusian atmosphere and clouds, and is also mapping the planet's plasma environment and surface characteristics, particularly temperatures.
As one of the brightest objects in the sky, Venus has been known since prehistoric times and as such has gained an entrenched position in human culture. It is described in Babylonian cuneiform texts such as the Venus tablet of Ammisaduqa, which relates observations that possibly date from 1600 BC. The Babylonians named the planet Ishtar , the personification of womanhood, and goddess of love.
Likewise believing Venus to be two bodies, the Ancient Greeks called the morning star, Phosphoro, the "Bringer of Light". The evening star they called Hesperos, the "star of the evening", but by Hellenistic times, they realized the two were the same planet. Hesperos would be translated into Latin as Vesper and Phosphoros as Lucifer ("Light Bearer"), a poetic term later used to refer to the fallen angel cast out of heaven.
Venus was important to the Maya civilization, who developed a religious calendar based in part upon its motions, and held the motions of Venus to determine the propitious time for events such as war. They named it Noh Ek', the Great Star, and Xux Ek', the Wasp Star. The Maya were aware of the planet's synodic period, and could compute it to within a hundredth part of a day.
Venus is important in many Australian aboriginal cultures, such as that of the Yolngu people in Northern Australia. The Yolngu gather after sunset to await the rising of Venus, which they call Barnumbirr. As she approaches, in the early hours before dawn, she draws behind her a rope of light attached to the Earth, and along this rope, with the aid of a richly decorated "Morning Star Pole", the people are able to communicate with their dead loved ones, showing that they still love and remember them. Barnumbirr is also an important creator-spirit in the Dreaming, and "sang" much of the country into life.