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October 2008

ASTRONOTES
Incorporating FRIENDS' NEWSLETTER 400 years of the Telescope Halloween Astronomy Who invented the Telescope? Who named the Constellations? The night sky this month

ARMAGHPLANETARIUM


2 Astronotes October 2008

The many inventors of the telescope
By Colin Johnston, Science Communicator This month marks four centuries since the telescope was invented ... or does it? The invention of the telescope revolutionised astronomy. In 1608 suddenly the Moon became a world with craters, mountains and seas, the planets, which had been points of light during all the previous millennia, became spheres, some with satellites of their own, the Milky Way, once a pale smudge across the sky could be seen to be stars without number. Through telescopes, everywhere in the night sky suddenly acquired more depth and more wonder. As everyone knows, the great Italian scientist Galileo Galilei (1564-1642) devised the first telescope. Using it to observe the Moon's craggy face, Jupiter and its hitherto unseen satellites, and much more, he also was starting on the path to confrontation with the religious authorities. However, like many well-known facts from history, this is in fact completely wrong. Galileo did not invent the telescope. telescope. There is some evidence that some kind of telescope was in use in England a full five decades before Galileo. One Leonard Digges (c15201559), a surveyor, mathematician and unsuccessful revolutionary was said to have "discovered things farre off" with "proportional glasses" in the 1550s. His son Thomas (c1546-1595) was another important scholar, his book `Prognostication Everlasting', the first published work in English to discuss the Copernican model of the Universe, suggested that the stars extended infinitely in all directions. How he reached this conclusion is not known but it is possible that he had been inspired by a telescopic view of the Milky Way. Neither of the Digges made any effort to publicise or disseminate this discovery. They were not full-time scientists, both had major distractions. A Protestant, Leonard Digges participated in an abortive attempt to overthrow Queen Mary, a Catholic, which led to the confiscation of all his property and his narrowly avoiding execution (perhaps he would have been better sticking to

"Through telescopes, the night sky suddenly acquired depth and wonder "
Who did actually invent the telescope? We are not exactly sure. In some ways it is surprising that they were not invented earlier in history. Spectacles had been in use in Europe since the 1350s or even before. In the following centuries probably thousands of people idly playing with lenses would have placed one in front of another and looked through the pair. Many of them must have noticed that they could see a distant object as though it were closer, yet mentally filed away this fact as a mere interesting curiousity. Apparently none applied this knowledge. It is also curious that the indefatigible astronomers and inventors of Imperial China never devised a

The Sun-centred Universe from `Prognostication Everlasting'. Did the Digges family make and use a telescope in the 1550s?

Image Credit: Wikimedia.org


October 2008 Astronotes 3 science). In contrast, Thomas was a pillar of the (Protestant) Elizabethan establishment being an MP and government advisor, so science was a hobby rather than a full-time occupation for him. There are other descriptions of what may have been early prototype telescopes from elsewhere. Turkish polymath Taqi al-Din (1526-1585) made "a crystal that has two lenses displaying in detail the objects from long distances" about the year 1574 but the book where he described its construction has been lost so we cannot authoritively say this was a telescope. Similarly, the Italian Giambattista della Porta (c1535-1615) described a possible telescope in his "Natural Magic" of 1589. Later della Porta claimed to be the inventor of the instrument, but died while writing the book in which he was to set out his case for priority. French-born spectacle-maker Juan Roget has recently been claimed as another possible inventor. In the 1590s, Roget was working in Gerona, Spain and sold a tubular `glass' which may have been a telescope.

The man who probably didn't invent the telescope but got the credit anyway: Hans Lipperhey (also known as Lippershey or Lippersheim). Lipperhey was born in Germany but became a Dutch citizen in 1602. He has an asteroid and small lunar crater named in his honour. Hans Lipperhey officially invented the telescope, so we are celebrating his achievement this month. However Lipperhey's case for priority is not as clear-cut as it may seem. Two other spectacle-makers, Sacharias Jansen and Jacob Metius (also known as Jacob Adriaanszoon) also claimed the invention. Jansen's workshop was close to Lipperhey's and he also tried to patent the telescope just fifteen days after his neighbour. Perhaps there was a degree of espionage going on... Lipperhey was said to be honest and pious while Jansen had dabbled in forgery and other shady enterprises. Metius may have independently made a telescope even earlier than Lipperhey but if he did, he did not demonstrate it publicly.

"There is evidence that some kind of telescope was in use in England 50 years before Galileo"
None of these putative inventors have been officially remembered for making the first telescope. That honour is held by Dutch spectacle-maker Hans Lipperhey (1570-1619), who on 2 October 1608, applied for a patent for an instrument "for seeing things far away as if they were nearby" (its magnification was about 3x). Lipperhey is said to have been inspired when he noticed children playing with lenses in his shop. His application was turned down, as the patent office officials regarded his telescope as being too easy to duplicate. He still profited though as he received several orders to build similar telescopes and pairs of binoculars for customers and he was paid by the Dutch government for his ingenuity. This official interest was not because of the telescope's scientific potential, but rather as a means to identify distant and potentially hostile vessels. Telescopes in the 1600s were as important for national defence as radar would be in the 1940s.

"Galileo could have invented the telescope himself, but did not until he had heard that it been invented!"
These original Dutch telescopes were of course refractors, but used a convex and a concave lens to create upright images making them ideal for terrestrial use. Telescopes were soon being

Image Credit: Wikimedia.org


4 Astronotes October 2008 the city. Soon he was enjoying a promotion and doubled salary granted by the grateful Doge (the city's elected leader for life) but was also observing the night sky with his telescope and its successors. `Enjoying' is probably the wrong word as he was heard to grumble that he deserved a more generous recompense. He set out to do something about it, using his telescope to further advance his career.
Image Credit: Wikimedia.org

The man who definitely didn't invent the telescope but was quick to exploit it. Galileo is one of history's most celebrated scientists. made throughout the Netherlands and before long were in use all over Europe. So why is Galileo so important to the story? In May 1609 Galileo, then teaching in Venice (an independent city state at the time), heard of this new "Dutch perspective glass" and without actually seeing one made his own version. His prototype was based on a lead tube and like the Dutch telescopes used convex and concave lenses. He found its performance disappointing and he redesigned it. Within days, he had made a better telescope using two convex lenses to achieve a higher magnification. It seems Galileo could have invented the telescope himself, but did not until he had heard that it had already been invented!

Clearly Galileo was not the kind of man to miss an opportunity, shortly after discovering the four major moons of Jupiter, he named them after the hugely powerful Medici family (this was not permanent: the Medician Planets are today's Galilean Satellites). This artful piece of pandering landed him the well-paid job of Mathematician and Philosopher to the Grand Duke of Tuscany, and he returned to the Italian mainland. This move disgruntled the Venetian authorities who had worked hard to secure his promotion and associated perks only months before. Today Galileo is remembered for his science rather than his one-upmanship. Undoubtedly Galileo was the first to use the telescope as a serious scientific instrument rather than a curiosity. He documented his observations, analysed them and speculated...the rest was history...(for more on Galileo's career see `Astronomy Greats: Galileo' by Naomi Francey in the July 2007 Astronotes) In the next four centuries, astronomical telescopes proliferated and evolved. These first telescopes were all refractors, reflecting telescopes (invented by Isaac Newton -- or were they? The origin of refractors is as murky as that of reflectors) came into use in the 1680s. In the twentieth century, telescopes to observe the Universe in other wavelengths, radio, infra-red, gamma rays and so on were devised. Imagine how little we would know of the Universe without telescopes and you will realize how important their invention has been, no matter who really deserves the credit.

"Galileo set out to use the telescope to further his career"
The wily scientist was quick to see the device's potential: he climbed a watch tower to demonstrate the instrument's utility as a naval early warning device to the Venetian senate. After successfully spotting approaching ships with his telescope a full hour before watchmen with no optical aids, he descended, and no doubt with a flourish, donated the telescope design to

Moon Phases, Oct 2008
Tue 7 Oct Tue 14 Oct Tue 21 Oct Wed 28 Oct First Quarter FULL MOON Last Quarter NEW MOON


October 2008 Astronotes 5

The Ten Greatest Telescopes in History?
developed an improved version which became known as the "Newtonian Telescope." Developments in telescope design and technology continued throughout the 18th and 19th centuries, and during the 20th century numerous telescopes were developed which could operate in a wide range of wavelengths from radio to gamma-rays. Nowadays there are an astonishing number of astronomical instruments available. I wonder what our readers might consider as the top ten greatest telescopes, to start you thinking here are my suggestions. 1. Galileo's Telescope : famously, after missing the opportunity to see a model of the newly invented device for "seeing faraway things as though nearby," around 1609, Galileo worked out the principle of the telescope and re-invented the instrument with about 3x magnification He pubImage Credits: via Wikimedia.org

The Leviathan of Parsonstown An illustration of the giant telescope from the 1860s. By Nigel Farrell, Education Support Officer This month marks the 400th anniversary of the telescope. Although there are some records which cite pre-17th century instruments which used lenses, it is now widely accepted that the first practical refracting telescopes were in use in the Netherlands by 1608. Three individuals, Hans Lippershey, Zacharias Janssen and Jacob Metius, all Dutch spectacle makers, are credited with its invention. In 1609 Galileo Galilei is said to have greatly improved upon the original design and in fact is often incorrectly identified as the inventor of the telescope. Galileo's observations led him to challenge the long held geocentric view of the universe, where the universe revolves around the Earth and accept the heliocentric theory proposed some 50 years earlier by Nicholas Copernicus, in which the Earth revolves around the Sun. Galileo was subsequently branded a heretic by the church. Which leads one to wonder how the medieval and renaissance church would have reacted had it known that our Solar System was only one small part of one of countless galaxies each containing innumerable stars. The first reflecting telescopes were developed around 1616, and by 1668 Isaac Newton had

French MP FranГois Deloncle proposed the Paris Exhibition Telescope and was ridiculed for his pains


6 Astronotes October 2008 The telescope rested on seven concrete and steel pillars and was designed to project images onto a large screen. Unfortunately though the telescope became the butt of many uncomplimentary jokes and cartoons of the period.Although it was optically a first-class instrument, its mount made it virtually useless for science!
Image Credit: created with NASA Worldwind software

5. Hubble Space Telescope: Hubble is the largest space telescope yet built and was carried into orbit by the Space Shuttle Discovery in April 1990.Hubble's position outside the Earth's atmosphere allows it to take extremely sharp images with virtually no background light and its 2004 Ultra Deep Field Image is the most detailed photograph of the universe's most distant objects ever made. Hubble is also the only telescope ever serviced in space by astronauts with the fifth and final mission originally due to begin on 8 October 2008 but now postponed. 6.The Very Large Telescope (VLT): the VLT is a collection of four telescopes located on Cerro Paranal, a 2635 m high mountain in northern Chile. Each telescope is 8.2 metres in diameter. In 2004 The VLT produced some of the first infrared images of extrasolar planets and more recently has found evidence for a massive black hole at the centre of the Milky Way. 7. The Subaru Telescope: Subaru is telescope of the Japanese National cal Observatory. Located in Hawaii, named after the famous star cluster also known as the Seven Sisters. the flagship AstronomiSubaru is the Pleiades

The Leviathan of Puerto Rico? This satellite view of the Arecibo Observatory shows the vast radio telescope dish. lished his initial telescopic astronomical observations in March 1610 in a short paper entitled Sidereus Nuncius (the Starry Messenger). 2. The Leviathan of Parsonstown: Holding the title of the world's largest telescope from 1845 until 1917 the Leviathian was a 72 inch (1.8m) giant constructed by William Parsons at his Estate, Birr Castle, in Co Offaly, Ireland. The telescope mirror was made from speculum metal, an alloy of copper and tin, and was the first to detect the spiral structure of some galaxies. 3. Arecibo Observatory: An extremely sensitive telescope located in the depression of a giant sinkhole in Puerto Rico. At 1000.6ft (305m) the Arecibo radio telescope is one the largest telescopes ever constructed. It gained infamy after sending out the Arecibo message, an attempt to communicate with extraterrestrial life in 1974 and was also featured in the James Bond movie GoldenEye (where it posed as a submersible satellite dish). 4. Great Paris Exhibition Telescope of 1900: Built as the showpiece of the Paris Universal Exhibition of 1900 the telescope was 197ft (60m) long with a reflecting mirror of 6.6ft (2m) in diameter.

8. The Hale Telescope: Named after the American astronomer George Hale this giant 200 inch (5.1m) diameter telescope was the world's largest between 1945 and 1975. Weighing in at 14.5 tons Hale's mirror is close to the maximum size that can be made rigid enough for a telescope mirror and amazingly continues to be used for scientific research every clear night from its location in San Diego County, California. 9.The XMM-Newton: named in honour of Isaac Newton the XMM is an orbiting X-Ray telescope launched by the European Space Agency in 1999. The telescope is 33ft (10m) long and weighs some 3800kg. Its information is processed at European Space Astronomy Centre and


October 2008 Astronotes 7 at the XMM-Newton Survey Science Centre at the University of Leicester and a scale model can be seen here at the Planetarium. 10.The Lovell Telescope: When constructed in the mid 1950s the Lovell telescope at the Jodrell Bank Observatory in the northwest of England was the largest steerable dish radio telescope in the world at 76.2 m (250 ft) in diameter. It became operational in 1957 in time to track Sputnik the first artificial satellite. Outside of scientific research it also served as an early warning system during the Cuban Missile Crisis of 1962 when it was pointed towards the Iron Curtain. You might wonder why I haven't included our own telescope here at the Planetarium but I feel that is a different story for another day. Feel free,

Hubble Space Telescope in orbit around the Earth. however, to compile your own top ten and e-mail it to us here at info@armaghplanet.com.

Naming the constellations
By Orla O' Donnell, Education Support Officer Cassiopeia, Orion, Ophiuchus...constellation names roll off the tongue of the planetarium staff like honey from the back of a spoon. We use them daily either in our live star show `Pole Position', in education workshops or just in conversation. Most people also unconsciously use constellation names whether discussing what their `star signs' predict for their love life this month or how their Toyota Carina car is running (Carina is a southern hemisphere constellation). Two months ago I explored the history and origins of star names in an article for Astronotes and in this article I would like to explore how we came to have 88 constellations mapping the stars in the night sky, and the history of constellation names. A constellation is basically defined as a group of stars that can be joined together to form an image that represents an object, creature or human. Most of the stars in the well-known constellations are among the brightest stars in the night sky. It is claimed that our ancestors have tried to chart the patterns in the stars for more than 17 000 years. Archaeologists have discovered paintings on the walls of the Lascaux caves in Southern France which some believe represent the Pleiades and Hyades star clusters. The cave drawings are dated to be 17300 years old, these primitive paintings added to oral history emphasize the importance of the stars to early human society.

" ...people use constellation names discussing what their `star signs' predict for this month.. "
The original concept of the Universe stated that the Earth was at the centre of the known Solar System and the stars surrounded it, all fixed inside a giant celestial sphere. Like star names the tradition of collecting and maintaining catalogues of constellation names lie in the great civilizations of the Middle East in the region known as Mesopotamia. This lies in modern day Iraq and Syria. Here the ancient Sumerians and Babylonians built some of the world's first advanced societies and much of modern astronomy owes a great debt to these cultures. It was later in this time of limited astronomical knowledge that the `Almagest', the first real

Image Credit: NASA


8 Astronotes October 2008
Image Credit: US Naval Observatory and Hubble Space Telescope Science Institute

catalogue of constellation names was compiled by Ptolemy of Alexandria, an astronomer who was believed to be an ethnic Roman living in Egypt around 150 AD. It was Greek mythology that has had the most impact on the naming of constellations; over half of the current 88 constellations which have been sanctioned by the International Astronomical Union are linked to the Greek tradition codified by Ptolemy. Ptolemy's text was lost to European thought with the Dark Age which followed the decline of the Roman Empire.

Taurus 15 500 years later as depicted by Hevelius.

"Like star names the collecting of constellations' names lie in the great civilizations of the Middle East"
Just as with star's names it was advancements in Arabic society that kept the familiar constellation names alive with the republication of Ptolemy's `Almagest' in Arabic around 820 AD. This was translated into Latin and re-introduced into Europe. Most of the traditional constellations that are widely known and remembered are linked to the wonderful tales that are embedded in Greek mythology. The stars are divided up into mythical creatures like Pegasus the winged horse and heroes of old like Orion and Hercules. Ptolemy's work only included 48 constellations stretching across the northern hemisphere and his work would be the defining collection of constellations for more than 1400 years

Most of the southern skies were uncharted by European astronomers until the 16th and 17th centuries when this celestial gap was filled in by Westerners. Dutch explorers Peter Keyers and Frederick de Houtman added twelve further constellations to Ptolemy's original 48. The Polish and French astronomers, Johannes Hevelius and Nicolas de Lacaille are just two more of the many contributors to modern constellation names.

"...aboriginal communities used the constellations as a calendar "
Rather than dipping into ancient mythology, the men who named these `new' constellations used names from their era of exploration and burgeoning scientific experimentation. There are constellations named for exotic creatures (exotic to Europeans that is), Tucana (the toucans), Chamaeleon (the chameleon) and Volans (the flying fish). Oceanic travel is reflected in the names of Carina (the ship's keel), Sextans (the sextant), Pyxis (the compass) and Vela (the sails) among others. Scientific instruments and equipment are celebrated in the names of constellations such as Horologium (the clock), Microscopium (the microscope), Fornax (the chemical furnace ) and, most appropriately of all, Telescopium (the telescope). In the end there was over a hundred named constellations, and not all were accepted by everyone, so not every one of these new names were adopted. It was not until 1930 that we arrived at the current recognized number of 88 constellations which cover the entire area of 41 253

Image Credit: BBC

Taurus and the Pleiades? The now extinct auroch was a favorite subject of the ancient artists of Lascaux. Perhaps they saw the head of one these beasts in the winter sky. Could the six dots represent the Pleiades?


October 2008 Astronotes 9 square degrees of sky. It was a Belgian, EugХne Delporte, who drew the boundaries for the 88 "modern" constellations on behalf of the IAU. Despite the modern constellations of the southern hemisphere bearing European names, these parts of the skies were not uncharted before the arrival of the Europeans. Obviously they have been long known to the indigenous peoples. In Australia, the aboriginal community has a strong cultural tradition of astronomical study, using the appearance and disappearance of particular constellations as a sort of calendar. The appearance of Orion, for example, signals the birth of dingo puppies and the disappearance of Lyra shows the appropriate time to collect eggs. So although in the west we may only recognize officially 88 constellations it is important to remember the importance that so many cultures attach to the stars.

The Sky in October
Image Credit: : NASA, ESA, and C.R. O'Dell (Vanderbilt

around 2:30am. If you're a bit earlier you can see Jupiter, moving from south to south west as the sun sets between 7:00pm and 9:00pm. Jupiter will set just after 10:00pm in the south west. In the north east you can see Auriga the Charioteer, Camelopardis the Giraffe and Lynx.

"The Egyptians believed Aquarius caused the annual flooding of the Nile River"
The Helix Nebula is a cloud pattern formed by a dying star and contains a tiny white dwarf star at the centre. By Tracy McConnell, Education Support Officer Welcome back to the Night Sky Guide for October. For the last few months I've been reminding you about the long days and short nights. This is starting to change. By the middle of October it will be completely dark before 9pm, thus allowing us more time to enjoy the night sky. It will however be getting colder so it would be wise to invest in a warm pair of gloves and woolly hat, and keep a warm drink on hand. Also remember that British Summer Time ends on Sunday 26 October and the clocks go back one hour. If you are stargazing on the 15th of the month at around 11:00pm, you will see several patterns from the last few months. The Summer Triangle is in the WSW and as the night moves on it moves north and slowly disappears below the horizon. Hercules is in the west and sets The Great Square which forms the belly of Pegasus, the Winged Horse, is facing south. Our family of constellations, Cassiopeia, Cepheus, Andromeda and Perseus are in the east-facing direction, from mid-sky to overhead. Capricornus the Sea-Goat is facing SSW. Capricornus is one of the signs of the Zodiac, which are constellations that form a band around the Earth. This band encompasses the paths of the Sun, Moon and planets across the night sky, and there are several other Zodiac signs visible during this month. The first of which is Aquarius the Water Bearer, which is a large jumbled sprawling pattern that faces SSW and is low in the sky. Aquarius was believed by the Babylonians to control this region of the sky containing the "watery" constellations. The Egyptians believed that it was Aquarius who caused the flooding of the Nile River every year. Though this constellation contains quite dim stars, it has two hidden delights. It is home to the Helix Nebula, and the M2 Globular Cluster. The Helix Nebula is a cloud


10 Astronotes October 2008 pattern formed by a dying star, and can be found towards the southern end of the constellation. The two brightest stars in Aquarius represent his shoulders, and M2 is a large cluster of stars which sits in the proposed head of the pattern. In the middle of the sky facing SE is another large but faint constellation, which resembles a pair of ram's horns. This is not Aries, it is Pisces the Fish, our next Zodiac sign. You can also find Pisces using the Great Square. When facing south, one of the fish of Pisces is a small circle of stars which sits directly south of the square. The fish are supposedly tied together by a cord at their tails. These two fish were believed to have saved the Greek goddess Aphrodite from Typhon, the dragon-headed monster. Our third Zodiac sign this month is Aries the Ram, which will be difficult to see around the 15th. This is due to the Moon passing through it and although not full, the moon will be just entering the waxing gibbous stage, and it so will still be very bright. By the 20th the Moon will be only half full and will have moved on through the sky to allow you a better look at Aries. Aries is found in the ESE direction at approx 11:00pm and, on our Sky and Telescope star-chart, looks like a small line with a curve on the south end. In Greek Mythology, Aries was the ram with a golden fleece which Jason and the Argonauts went questing after. The final member of the Zodiac which we are going to look at this month is Taurus, the Bull. The bull is a transformation of our favourite playboy god, Zeus. After the ladies fifty per cent of the time, Zeus turned himself into a beautiful white bull so that he could approach the young maiden Europa, while she was playing with some friends on the beach. Europa hugged the bull and climbed onto its back. Zeus then jumped into the sea and carried Europa off to the island of Crete

The Crab Nebula the remains of a star that died in a spectacular supernova and was witnessed by Chinese astronomers in 1054. where Zeus revealed his true self to her and she later bore him three children. Taurus is represented in the sky as the front half of the bull because the rest of its body is below the surface of the water. The stars in this constellation are bright and easily found. The horns are in the pattern of a V and are facing directly east at this time. There are two bright stars at the tip of the horns, a cluster around the face and snout and a line of stars down the body. The brightest star which is called Aldebaran, has a reddish tone and marks the eye of the bull. Taurus also contains the remains of a star that died in a spectacular supernova in 1054. It was so bright it could be seen, even during the day, for weeks after the explosion. It was later designated M1 and named the Crab Nebula and can be found between the two horn tips. Next month we will get to learn about the Pleiades cluster behind Taurus, the next Zodiac sign Gemini, and Orion the Hunter. Enjoy your stargazing, and I'll see you next month.

The astronomy of Halloween

By Alyson Kerr, Education Support Officer Halloween is not just about ghosts and other

monsters, it holds some very strong astronomical ties. The origin of Halloween actually dates back to the ancient Celtic festival of Samhain (pronounced Sow-in). The Celts date back to

Image Credit: FORS Team, 8.2-meter VLT, ESO


October 2008 Astronotes 11 Day, and I am sure many of you have been to the Ould Lammas Fayre in Ballycastle for some Yellow Man (a sweet man-made honeycomb that can make your teeth stick together!). The last date is 31st October or Halloween and is the last "cross-quarter" day on the Solar Calendar.

Image Credit: NASA

"Halloween marks the transition between summer and winter and even life and death "
Between Solstice and Equinox lie the crossquarter days. more than 2000 years ago and inhabited across a wide region including Ireland, the present-day United Kingdom and northern France. Halloween is the mid-point between the autumnal equinox and the winter solstice otherwise known as a "cross-quarter" day. An equinox in astronomy is the moment in time when the centre of the Sun can be observed to be directly above the Earth's equator. This occurs around 20 March and 23 September every year, so an equinox will occur in the Spring and Autumn. Solstices also occur twice a year, when the tilt of the Earth's axis is most orientated toward or away from the Sun. Summer and Winter are marked by solstices on the 21 June (Midsummer's Day) and 21 December. The solstices, together with the equinoxes, are traditionally connected with the seasons. There are four "cross- quarter" days on the Solar Calendar and the Celts were among the few cultures that used them to mark the change in season. These are days that you may already recognise as minor holidays. The first is the 2 February or Groundhog day, in modern times mainly recognised in America, but widely celebrated by the Celts as the beginning of Spring. May Day (1 May) is the second "cross-quarter" day in the Solar Calendar, which many of us still celebrate today with a welcome bank holiday. The third date is less well known but one you will recognise. The 1 August marks Lammas The Celtic New Year began on 1 November and Halloween marks the transition between summer and winter, light and dark and even life and death. For centuries, cultures all over the globe have believed in spooky happenings on this date. The Celts believed that on this night, the boundary between the living and dead became blurred. It was a night to remember the dead. Many believed that the ghosts of the recently deceased would come back to visit. They also believed that it was easier to communicate with departed loved ones and make predications about the coming months. The Druids played a large part in this celebration, making sacrificial bonfires where crops and animals were sacrificed to the Celtic deities. This may also have been where the tradition of dressing up in costume originated. They wore costumes of animal skins during the celebration and during the evening left presents of food to aid the spirits on their journey. Many modern traditions originate from the Celtic people and the rituals used to commemorate a day that originally marked the cycle of the season. This Halloween I hope you will all carry on these traditions in modern costumes! It also seems appropriate that we carry on these traditions with our very own celebrations at Armagh Planetarium. We will be holding our annual Halloween Party complete with a fancy dress competition, spooky storytelling and a show in our digital theatre on Halloween night. Feel free to come along and join in the festivities but remember to book in!


12 Astronotes October 2008

Image of the Month

This stunning image of active galaxy NGC 1275 seems particularly appropriate for this time of year due to its spider-like appearance which comes from brightly glowing filaments of gas extending out as much as 20 000 light years (6.1 kpc) into deep space. Spiders, as I'm sure you know, are often closely associated with witches, and many a spider has met a grisly demise as an ingredient in a spellcasting broth. Spiders often partnered witches as `familiars', small, creeping animal servants. The spinner of webs was said to be an arch-trickster, and a silent and murderous trapper, small enough to hide in the hood of a witch's cloak and whisper

instructions in her ear. Despite it soon being Halloween, the spidery image of NGC 1275 has a much less sinister history. It is the central, foremost member of the Perseus Cluster of galaxies some 300 million light years (93 Mpc) from Earth. This giant elliptical galaxy is also a powerful source of x-ray and radio emissions. The red glowing filaments are accretions of matter caused by nearby galaxies falling into it, feeding a supermassive black hole at its centre, much like a spider collecting flies from a web. NGC 1275 is approximately 100 000 light years (31 kpc) across and is 230 million light (70.5 Mpc) years away. (Caption by Nigel Farrell, Education Support Officer)

www.armaghplanet.com
Astronotes, Incorporating Friends' Newsletter is published monthly by Armagh Planetarium, College Hill, Armagh, Co. Armagh BT61 9DB Tel: 02837 523689 Email: cj@armaghplanet.com Editor: Colin Johnston Assistant Editor: Alyson Kerr ©2008 Armagh Planetarium All rights reserved

Image Credit: NASA, ESA, Hubble Heritage (STcI/AURA)