Pedro Castle, Monday February 11th

As darkness falls on Monday the bright star Aldebaran can be seen directly overhead.
Aldebaran is the brightest star in the constellation Taurus and one of the brightest stars in the nighttime sky. It has the Bayer designation Alpha Tauri. Because of its location in the head of Taurus, it has historically been called the Bull's Eye. Aldebaran has the appearance of being the brightest member of the more scattered Hyades cluster, which is the closest star cluster to Earth. However, it is merely located in the line of sight between the Earth and the Hyades, and is actually an independent star.
In 1997, a possible substellar companion was reported, with a mass at least 11 times that of Jupiter with an orbital period of around 2 years, however this has not been confirmed.
Aldebaran is a K5 III star, which means it is orangish, large, and has moved off of the main sequence after exhausting the hydrogen fuel in its core. It has a minor companion (a dim M2 dwarf orbiting at several hundred AU). Now primarily fusing helium, the main star has expanded to a diameter of approximately 5.3 × 107 km, or about 38 times the diameter of the Sun.
The Hipparcos satellite has measured it as 65.1 light years away, and it shines with 150 times the Sun's luminosity. With an apparent magnitude of 0.87, it is the 14th brightest star.
The name Aldebaran comes from the Arabic (الدبران al-dabarān) meaning "the follower" and refers to the way the star follows the Pleiades star cluster in its nightly journey across the sky.
In Persia it was known as Satvis and Kugard.[4]
It is known as 畢宿五 (Bìxiùwŭ, the Fifth Star of the Net) in Chinese.
Aldebaran is identified as the lunar mansion Rohini in Hindu astronomy and as one of the twenty-seven daughters of Daksha and the wife of the god Chandra.
The Romans called it Palilicium.
For the Dakotas (a branch of the Native American Sioux tribe), Aldebaran took on a heroic aspect. The young star was the child of the sun and the lady Blue Star. One day, he desired to hunt the white buffalo (the Pleiades). After he pulled up a sapling to make a spear, a hole was made in the ground and he could see all the people of Earth down below. The white buffalo took this chance to push him through. He was found by an old woman and was to be known as Old Woman's Grandson. On Earth, he killed many strange monsters that had been troubling the Native Americans; one monster of which was a serpent that caused drought. The young hero killed the serpent, releasing a great stream of water that became the Mississippi River. In time, Old Woman's Grandson remembered the white buffalo and returned to hunting him in the sky to fulfill his destiny.
For the Seris of northwestern Mexico, this star is providing light for the seven women giving birth (Pleiades).
Noticeably redder, and brighter, is the nearby planet Mars.
Mars is close to the β (beta) star of Auriga on the illustration above.
Called Menkalinan, it is a double star consisting of two blue white giant A2 class stars. They have magnitudes of 1.9 and 2.7 and are 90 light years distant.

January 11th 2008

Although the eye is drawn to bright Mars and the rising winter constellations, almost directly overhead as darkness falls is the small, faint constellation of Aries.
Aries is one of the least conspicuous of the zodiacal constellations, and has only two stars above third magnitude. These are Hamal and Sheratan, the Alpha and Beta stars of the constellation. Unusually, these two stars not only appear to be close together in the sky, but actually are: they lie just six light years from one another.
The Hipparcos satellite indicates that Hamal is about 65.9 light-years from Earth. Combined with its intrinsic brightness, this relatively small distance makes the star shine at an apparent magnitude of 2.01, the 47th brightest star in the sky.
Beta Arietis is the Ram's second horn. It also has the traditional name Sharatan (or Sheratan or Sheratim), and the Flamsteed designation 6 Arietis.
Al Sharatan means "the two signs", a reference to the star having marked the vernal equinox together with its binary partner Gamma Arietis several thousand years ago. It is 59.6 light years from Earth.
Gamma Arietis, Mesarthrim, shines third among the stars of the flat triangle that make the classical figure of Aries, the Ram (for that reason gaining the Gamma designation). The name (derived from Arabic) originally came from the same root as that for the Beta star, Sheratan (meaning "the two"), but was corrupted by mistranslations into its current form.
Gamma Arietis is a beautiful double star, which was discovered quite by chance in 1664 when astronomer, Robert Hooke, was following the motion of a comet. Gamma Arietis is one of the earliest double stars on record to have been found with the aid of a telescope.
Teegarden's star, a recent (2003) discovery is also in the constellation. It is one of Sun's closest neighbors at around 12 light years away. It appears to be a red dwarf, a class of low temperature and low luminosity stars. This would explain why it was not discovered earlier, since it has an apparent magnitude of only 15.4 (and an absolute magnitude of 17.47).
Teegarden's Star was discovered on images taken by the NEAT program operated by NASA. Its name comes from its principal discoverer, Dr. Bonnard Teegarden, an astrophysicist at NASA's Goddard Space Flight Center.
It is thought to be quite likely that many other dim and easily overlooked red dwarf stars exist in the nearest 20 light years, as stellar population surveys show their count to be quite lower than otherwise expected.
Although dim, Aries is one of the oldest and most revered of all constellations. The ancient Babylonians, Egyptians, Persians and Greeks all called this group of stars "The Ram." It is the Zodiac's first constellation since the Sun, at one time, was entering Aries on the day of the vernal equinox...the moment when it crosses from the southern to the northern half of the celestial sphere. However, because of the Earth's precession, the Sun is now in Pisces at the vernal equinox. Nevertheless, Aries is still considered to be the symbolic first constellation of the Zodiac and Right Ascension continues to be measured from the first point of Aries.
In a bygone age, the Egyptians associated Aries with Amon-Re, the ram-headed supreme Sun God who symbolized power and fertility. The Mesopotamians' name for the constellation meant a military leader or prince. In Hebrew tradition, the ram represented the death-defying blood of the lamb smeared on the doorways as part of the original Passover, which preceded the Hebrew Exodus from Egypt. The Greeks related Aries to the story of the Golden Fleece, the hide of the flying ram that Jason (with the help of his beloved Medea) spirited away from the serpent in the Grove of Aries. This constellation is mentioned in "Phaenomena," authored by the Greek poet Aratus, which dates from the Third Century B.C., and Ptolemy, the great astronomer who lived and worked in Egypt during the Second Century A.D., cataloged this constellation.
The present name of this Zodiac Sign is Roman in origin, Roman mythology having been adopted from that of the Ancient Greeks. This faint and tiny cluster of stars first appeared on monetary coin in 6 A.D.
clear skies
Nick

Wednesday, 12th December 6.30 p.m.

Directly over head as darkness fall is the constellation Pegasus. Four stars form almost a perfect square that are about the same brightness. This is the "Great Square of Pegasus."
The "Great Square" forms the body of the Winged Horse. To connect the rest of Pegasus, you'll need to use the right side of the "square." Pegasus is flying upside down across the sky. From Markab (lower right corner) extends the head of the Winged Horse. The two front legs of Pegasus can be found off the star Scheat (upper right corner). The star Alpheratz is shared by two constellations, Pegasus and Andromeda. The star is actually considered to be a star of Andromeda.
51 Pegasi, a star in this constellation, is the first Sun-like star known to have an extrasolar planet. IK Pegasi is the nearest supernova candidate.
In Andromeda is the most famous deep sky object , M31.This is the Andromeda Galaxy, one of the most distant objects visible to the naked eye. It is an enormous spiral galaxy much like the Milky Way and is approximately 2.5 million light-years away.
Andromeda is the largest galaxy of the Local Group, which consists of the Andromeda Galaxy, the Milky Way Galaxy, the Triangulum Galaxy, and about 30 other smaller galaxies. Although the largest, it may not be the most massive, as recent findings suggest that the Milky Way contains more dark matter and may be the most massive in the grouping. However, recent observations by the Spitzer Space Telescope revealed that M31 contains one trillion (1012) stars, greatly exceeding the number of stars in our own galaxy. 2006 estimates put the mass of the Milky Way to be ~80% of the mass of Andromeda, which is estimated to be 7.1×1011 solar masses.
Bright Mars rises a little later that night, making its closest approach to Earth since 2005. Not often do we get a close look at Mars. It’s a small world to begin with, about half the diameter of Earth, and it spends most of the time far away on the other side of its orbit from us. Mars usually ranks as one of the most disappointing objects in amateur astronomy — a tiny, featureless orange blob. The only time we get a decent look at its surface markings, clouds, dust storms, and changing polar caps is for a couple of months every two years, when Mars comes closest (around its date of opposition).
This time around, Mars maxes out at 15.9 arcseconds when it passes closest to Earth on December 18th. That's nowhere near its record-breaking apparent diameter of 25.1" in August 2003. Even so, it's bigger than Mars will appear again until 2016.
Contrary to rumor, Comet 17P/Holmes has not faded away. From any dark starry-skied observing site, it remains visible to the naked eye. Although the comet is not as bright as it was when it exploded in late October, it makes up for its lack of surface brightness by sheer size: the comet is huge! It looks like a faint Moon-sized puff of cloud in the middle of the constellation Perseus--a really splendid sight.
For patient and wakeful people, the Geminid meteor shower can be viewed the night of December 13–14, with good prospects the following night as well.

Monday 12th November Pedros Castle 6:30 PM

There are few bright stars in the sky this time of year, which makes it difficult to easily make out many of the constellations.
However, one of the most distinctive constellations in the northern hemisphere, Cassiopeia, the vain Queen, is in the north when it is dark.
Cassiopeia, the wife of King Cepheus, ruler of Aethiopia, was beautiful, arrogant and vain, and it was these latter two characteristics which were to lead to her downfall. Her continual boast that both she and her daughter Andromeda were more beautiful than the sea nymphs, daughters of Nereus, the sea god, brought the wrath of Poseidon, ruling god of the sea, upon the kingdom of Aethiopia. Trying to avert such a fate, Cepheus and Cassiopeia consulted a wise oracle, who told them that the only way to appease the sea gods was to sacrifice their daughter. Accordingly, Andromeda was chained to a rock at the sea's edge, and left there to helplessly await her fate at the mercy of the sea monster. But Perseus arrived in time and saved Andromeda. Poseidon considered that Cassiopeia should not escape punishment entirely, and placed her in the heavens in such a position that she circles the celestial pole in an upside-down position for half the time.
Cassiopeia contains two stars visible to the naked eye that rank among the brightest in the galaxy, ρ (Rho) Cassiopeiae and V509 Cassiopeiae.
Rho Cassiopeiae (also Rho Cas) is a yellow hypergiant in the Cassiopeia constellation. It is about 8-10,000 light years away, yet can still be seen by the naked eye (in the Northern Hemisphere only), as it is 550,000 times brighter than the Sun. The surface diameter is 738 times larger than our sun's. Astronomers think Rho Cas may go supernova in the not too distant future, because it will have consumed most of the nuclear fuel in its core.
If we were to observe Earth's Sun from Alpha Centauri, it would appear to be in Cassiopeia.

The planets this month are late night objects. Mars rises shortly before midnight at the beginning of November, and will be visible just above the horizon by 10.30 on the night of the viewing.

Venus and Saturn are visible in the early morning sky.

Sunday 14th October 7.00 p.m. Pedros Castle

Directly overhead as darkness falls can be seen the distinctive shape known as the Summer Triangle, which consists of the stars Vega, Deneb and Altair. This noticeable pattern is known as an astronomical asterism, a group of stars seen in Earth's sky which is not an official constellation. The triangle connects the constellations of Aquila, Cygnus, and Lyra.
The largest of these three constellations is Cygnus, the Swan, also known as the Northern Cross. Cygnus contains several bright stars.
Deneb, α Cygni, is an extremely brilliant star, very prominent despite its distance (3230 light years). The blue supergiant forms the swan's tail, the upper end of the Northern Cross. It’s also the 18th brightest star in the sky.
Albireo, β Cygni, is at the swan's beak. It is one of the most beautiful double stars of the sky, a golden star easily distinguishable in a small telescope from its blue companion.
Lyra, dominated by its bright star Vega, is a much smaller constellation than Cygnus.
Vega is the second brightest star of the northern hemisphere (after Arcturus) and the fifth brightest star in all. It lies at a distance of only 25.3 ly. It was the first star to be photographed.
Aquila is a much harder pattern to distinguish, although Altair is easy to spot. Altair is located 17 light years away from Earth (about 159 trillion kilometers) and is one of the closest stars visible to the naked eye.

Behind the Summer Triangle lies some of the vast star fields of our Milky Way Galaxy, containing literally billions of stars. The dark band across the middle that seems to divide the stars is actually interstellar dust, which absorbs more visible light than it emits and so appears dark.

Jupiter is the only visible planet in the evening sky this month, shining bright in the south west.

Autumnal equinox falls on the 23rd, when the Sun can be observed to be directly above the Earth's equator. Night and day are nearly of the same length, and this signals the end of the summer months and the beginning of winter.

Friday 14th September Pedros Castle 7:00 PM

Friday, 14th September is our viewing date this month, 7.00 p.m. at Pedro Castle.
Sagittarius, the archer — whose brightest stars form the shape of a teapot — is now prominent in the southern sky.
Sagittarius has drawn his bow, and his arrow is pointing at Antares, the bright red heart of Scorpius, the scorpion. The archer is avenging Orion, who was slain by the scorpion's sting.
The constellation Sagittarius is one of the most interesting regions of the sky. The center of our Milky Way galaxy lies inside Sagittarius, about 26,000 light-years away. The constellation also contains several globular clusters — tightly packed collections of hundreds of thousands of stars.
The Milky Way is the galaxy where the Solar System (and Earth) is located. It is a barred spiral galaxy of a Local Group of galaxies within the Virgo Supercluster. The main disk of the galaxy is about 80,000 to 100,000 light-years in diameter, about 250,000 to 300,000 light-years in circumference, and outside the Galactic core, about 2,300–2,600 light-years in thickness. The galaxy is estimated to contain 200 billion stars but this number may be as high as 400 billion if small-mass stars predominate.
As a guide to the relative physical scale of the Milky Way, if the galaxy were reduced to 130 km (80 mi) in diameter, the solar system would be a mere 2 mm (0.08 inches) in width.
The Lagoon Nebula (also known as Messier Object 8 (M8) and NGC 6523) and the Trifid Nebula (also known as Messier 20 and NGC 6514) are giant interstellar clouds and H II regions.
An H II region is a cloud of glowing gas and plasma, sometimes several hundred light-years across, in which star formation is taking place. Young, hot, blue stars which have formed from the gas emit copious amounts of ultraviolet light, ionising the nebula surrounding them.
Nunki, 224 light years away from us, is the second brightest star in the constellation Sagittarius; its Babylonian name is of unknown origin. Blue-white Nunki is a B star and one of the hotter of the bright stars, radiating much of its light in the ultraviolet. Typical of its breed, it is a fast spinner, rotating with a speed of over 200 km/s – 100 times that of our Sun. Although still on the main sequence, Nunki is much more massive than the Sun and will exhaust its internal fusion reserves in another 50 million years or so.
Jupiter is the only planet visible in the evening sky, brilliant and unmistakable in Scorpius, above Antares. Early risers will be able to see Mars overhead before the dawn, and Venus and Saturn in the east.

Wednesday 15th August :730 PM Pedros Castle

CAYMAN ISLANDS ASTRONOMICAL SOCIETY
NEWSLETTER AUGUST 2007
We will aim to meet this month on Wednesday, 15th August, 7.30.p.m. at Pedro Castle, weather permitting.
The Perseid Meteor Shower occurs on August 12-13th. This year the new moon will leave the sky dark. Look to the eastern sky in the constellation Perseus. Between 2 a.m. and dawn on August 13, if you get away from city lights, you could see hundreds of meteors.
This is one of the best showers of the year. The Perseids are a result of debris in space left by comet Swift-Tuttle. Although the comet is nowhere near Earth, the comet's wide tail does intersect Earth's orbit. We glide through it every year in July and August. Tiny bits of comet dust hit Earth's atmosphere traveling 132,000 mph. At that speed, even a tiny smidgen of dust makes a vivid streak of light--a meteor--when it disintegrates. The shower is most intense when Earth is in the dustiest part of the tail.

The mythological illustration that I used last month included the constellation Scorpius, more schematically shown above.
Jupiter, the fourth brightest object to light up the heavens, after the sun, moon, and Venus, shines unmistakably in the southern part of the sky, and serves as a guide to the Scorpion.
This is a distinctive constellation with its wide head and body curving to its tail. Glowing with a reddish hue at the heart of this asterism is the bright star Antares, the sixteenth brightest in the sky, although out shone this month by close Jupiter.
Antares is in the middle of the scorpion's curving body and rivals Mars in its reddish tint. This brilliant red star is one of the behemoths of our stellar neighborhood. If you placed it at the center of our own solar system, it would swallow Mercury, Venus, Earth, and Mars, and almost reach Jupiter.
The Scorpion was sent by Gaia to kill Orion when Orion boasted he would slay all the animals of the Earth; now Orion and Scorpius circle each other on opposite sides of the sky.
The Chinese included these stars in the Azure Dragon, a powerful but benevolent creature whose rising heralded spring, and in Maori mythology, this constellation can be Maui's magic jawbone used to fish up the North Island of New Zealand.