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October 2007

ASTRONOTES
Incorporating FRIENDS' NEWSLETTER Sputnik's Fifty Year Legacy Heroes and Monsters in the Sky COS-B arrives in Armagh The Man Behind Sputnik France's Space City

ARMAGHPLANETARIUM


2 Astronotes October 2007

Sputnik's Fifty Year Legacy
By Wendy McCorry, Science Communicator An important anniversary in the history of space exploration takes place this month. Fifty years ago, on 4th October 1957, the Soviet Union launched Sputnik 1, the first artificial satellite to successfully orbit the earth. This simple basketball-sized sphere was to change the course of history, and its launch is now widely regarded as heralding the dawn of the space age. In 1952, the International Council of Scientific Unions declared that 1957-1958 would be named International Geophysical Year (IGY), to coincide with a predicted high point in solar activity. The council asked that artificial satellites be launched during this year in order to map the Earth's surface. In 1955, the US announced their intention to launch a satellite named Vanguard, possibly as early as November 1957, and they set about building and testing their equipment. The Americans were taken by complete surprise however, when the Soviet Union unexpectedly launched their own satellite, Sputnik 1, from
Image Credit: NASA

Celestial sphere Sputnik was a simple sphere with a set of whip antennae what is now the Baikonur Cosmodrome in Kazakhstan on 4th October, 1957. Sergei Korolev, the Soviet Union's head rocket engineer, had originally been working on a satellite named Object-D, which was due to be completed in 19578. Work on this satellite was being carried out by a number of different departments, and Korolev began to worry that the Soviet project was too ambitious and was not going to be ready in time to beat their US counterparts. With this in mind, he decided to postpone the complex Object-D project, and to concentrate instead on creating a simple, light and easy to construct satellite.

"The Americans were taken by surprise"
Sputnik (translated as `fellow traveller') was a polished aluminium alloy sphere filled with pressurized nitrogen. It was 58 cm in diameter and weighed approximately 83.6 kg. The satellite had four whip-like antennae and contained two 1 watt radio transmitters which emitted a repeating beep, each lasting for 0.4 seconds. Three silver zinc batteries supplied power to the transmitters, along with a ventilation fan. Sputnik was
Image Credit: NASA

The Man with a Plan Sergei Korolev led the project to launch the first satellite


October 2007 Astronotes 3 launched by a modified version of an R-7 rocket, a ballistic missile that would later be a major weapon in the Cold War (thankfully it was never to be fired in anger). When news of Sputnik's launch was broadcast over the radio and television, millions of people throughout the world endeavoured to catch a glimpse of the tiny object travelling through the sky. Although many people reported to have seen Sputnik, what they probably witnessed was actually one of the larger rocket stages which also went into orbit. Amateur radio operators were also able to pick up the distinctive beeping sound of the satellite's signal.
Image Credit: NASA Image Credit: NASA

Sputnik 1 disassembled The transmitters and their batteries filled the tiny sphere. he issued a statement congratulating the Soviets on their achievement. The Soviet Union struck again in November with the launch of Sputnik 2, a heavier satellite which carried a passenger on board ­ a dog named Laika. Laika was the first living creature to orbit the Earth, and gave the Soviets another first in space history.

"Sputnik 2 carried a dog named Laika"
Preparations for launch The image shows Sputnik 2's R-7 launch vehicle on the pad a few weeks after Sputnik 1's blast off. The two rockets were almost identical. The American response to Sputnik was one of hysteria, with newspapers reporting that if the Soviets could launch a satellite into orbit, then surely they were also capable of launching several satellites equipped with nuclear bombs. Senator Mike Mansfield announced to the nation, "What is at stake is nothing less than our survival". A notable exception to the hysteria came from President Eisenhower, who did not publicly comment on the event until five days later, when After the initial hysteria, the shock of being caught off guard by Sputnik sparked longer-term changes in American society, most significant of which was the establishment of NASA. In an effort to equip the nation for the technological challenges of the future, planetaria and science centres were opened; school curricula were changed to emphasize science and mathematics; and hundreds of millions of dollars went towards scholarships for science students and the purchase of scientific equipment for schools. America was gearing itself up for the US / Soviet `Space Race' which was to continue for the next 12 years, culminating in 1969 when the US


4 Astronotes October 2007 Space Program successfully landed a man on the Moon. So what became of Sputnik 1? Having completed around 1400 orbits of the Earth the tiny satellite is thought to have perished as it re-entered the Earth's atmosphere on January 4th 1958. Its mission may have lasted for only ninety-two days, but Sputnik has left behind an important legacy which continues to amaze and fascinate, even though the sound of its beeps have long since faded away.

The Autumn Night Sky
By Naomi Francey, Education Support Officer I just happened to be coming home late last night and gazed up at the night sky as I got out of my car. I couldn't help but notice the beautiful display that was above me, there was not a cloud in sight, a perfect night for stargazing. Autumn is a great season for observing the heavens because you are more likely to get a clear night and it's not as cold as winter so you don't freeze! In the spring night skies we use the Plough to find constellations like Leo the lion and BoЖtes, in the summer we use the Summer Triangle to find our way about the sky and in the autumn we use the Great Square. The Great Square can be found facing a south westerly direction and is part of the constellation Pegasus. Pegasus is the legendary flying horse and the Great Square is part of its body. The Great Square is made up of four bright stars which are quite bright compared to other Autumn stars. In Fig 1. the Great Square is the red outline which is used to find other constellations. The more stars you can see inside the Great Square the less light pollution at your location. So if you only see a few stars inside the square you would benefit greatly from stargazing in a more remote location. The first constellation that we will look at is Andromeda which is attached to the tip of the square (Fig. 1). Andromeda looks like an upside down capital "A" in the night sky with twigs for arms and where her head meets the corner of the great square is a star called Alpheratz. Andromeda was the daughter of Cepheus the King and Cassiopeia the Queen, and was meant to be sacrificed to Cetus the sea monster. Cetus was terrorising their country and the king and queen hoped that feeding him a princess would make him take his anti-social behaviour elsewhere. Thirty years ago the Andromeda Galaxy could be seen using the naked eye, but in the 21st Century with increasing urbanisation viewing this galaxy becomes quite difficult, even in the countryside. The

Image Credit: Naomi Francey, Education Support Officer

Figure 1: The Great Square and Andromeda Triangulum is also shown.


October 2007 Astronotes 5 Andromeda Galaxy is the largest in our local group of about thirty galaxies, and is the closest spiral galaxy to the Milky Way at about 2.5 million light years distance. The very appropriately named constellation of Triangulum (see Fig.1) can also be found just to the right of Andromeda but it is very faint. In the south east, you find the constellation of Perseus just below the constellation of Cassiopeia (Fig. 2). Did you watch the meteor shower there in August? Perseus was a hero and the son of Zeus who beheaded the evil gorgon Medusa. He carefully placed her head in a bag, because if anyone looked at the face of Medusa Figure 2 Perseus Many constellations do not resemble the creathey were automatically turned ture or object they are supposed to. Thie constellation Perseus to stone. Perseus flew away on Pegasus and, as he was flying home, is an exception, resembling a human figure. he noticed Andromeda chained to a rock, so he rescued her just before the sea monseveral hours and brightens again. This can be ster devoured her. He used the head of Medusa witnessed with the naked eye so no telescope is to turn the sea monster to stone and it was the required. Due to this behaviour Algol is someusual happily ever after fairytale ending. times referred to as the winking star. Why does There is something special within the constelit do this? Algol is part of what astronomers call lation of Perseus that is worth looking for. It is a an eclipsing binary system. This means another star called Algol which, every 68 hours, dims for dimmer star is orbiting Algol, in such a way that when it passes in front of Algol, Algol's light dims. The Algol system was the first of these systems to be discovered. Any earlier risers out there should look east just before sunrise. You will see a glorious bright star blazing away. This is no star, it is our neighbouring planet, Venus! These are just a few things to look out for in the autumn sky and no previous astronomy knowledge is required. So get your coats and hats on and go outdoors and explore the wonders of the autumn night sky!

Image Credit: Amazon.co.uk

Moon Phases, Oct 2007
Thurs Thurs Fri 19 Fri 26 3 October Last Quarter 11 October NEW MOON October First Quarter October FULL MOON

Movie Mythology Thie Andromeda and Perseus story received the Hollywood treatment in 1981. `Clash of the Titans' starred Laurence Olivier and a host of wonderful stop-motion monsters.

Image credit: Naomi Francey, Education Support Officer


6 Astronotes October 2007

The Man behind Sputnik
By Colin Johnston, Science Communicator Placing Sputnik 1 in orbit was a colossal achievement, yet the man responsible, Sergei Korolev, is not a household name. His story should be better known; his youthful dreams of flying into space were blighted by suffering but still came true in the end. A teacher's son, Sergei Pavlovich Korolev was born in 1907 in the city of Zhitomir in present day Ukraine. In childhood, like most small boys he was fascinated by aircraft and flying. Unlike most, however, he carried this interest forward into adulthood, training as an aeronautical engineer and leisure-time glider pilot. By 1929, when he graduated from Moscow's Bauman High Technical School (Russia's MIT) he had developed an interest in rocketry and the possibilities of space travel. He was not alone in this. The idea that one day soon people could travel to the Moon and beyond was in the air. In the 1920s and 30s, American, British, Soviet and German enthusiasts formed rocket clubs to carry out occasionally hair-raising experiments with liquid fuel rockets. Most infamous of these was Germany's VfR (Verein fЭr Raumschiffahrt or Space Travel Society). The nucleus of this group, including Wehner von Braun, later developed missiles for the Nazi regime.

"Korolev led the development of a rocket-powered glider"
In Moscow, Korolev founded an organization called GIRD (Gruppa Isutcheniya Reaktivnovo Dvisheniya or Group for Investigation of Reactive Motion). This society's achievements are unfairly unknown in the West; along with other Russian rocket clubs it performed a series of increasingly ambitious experiments on liquid fuel rocketry.

Sergei Korolev (in shirt) photographed in July 1954 with a dog that just returned to Earth after reaching an altitude of 100 kilometres in an R-1 scientific rocket. Paralleling the VfR's experience in Germany, Korolev's GRID's success brought government attention; in 1933, the group was reorganized into the state-sponsored RNII (Jet Propulsion Research Institute) with Korolev as Deputy Chief of the institute. There Korolev led the development of missiles and of a manned rocket-powered glider. This craft was never to fly though. In one of those horrific incidents so typical of Stalinist rule, Korolev was arrested on trumped-up charges of sabotage in 1938, and imprisoned in a series of brutal Siberian prison camps. The prison regime included forced labour in a gold mine and regular beatings from guards. Many of his RNII colleagues were also rounded up at the same time, most were executed, so Korolev was in fact one of the lucky ones.

Image Credit: NASA


October 2007 Astronotes 7 Unsurprisingly, Korolev's health suffered in these terrible years and he never recovered from the experience. In late 1940 he and many other talented engineers in Soviet prisons were allowed to work on military projects from their cells. During this period Korolev helped with the development of the Tu-2 bomber, one of the great aircraft of World War II (and again almost unknown outside Russia). Korolev's conditions improved further in 1944 when he was released on parole to use his expertise to investigate German military rockets. What he thought of this change in circumstances is not recorded, doubtless he was just glad to be free (or as near as one could be free in Stalin's Russia). manned space vehicles. The once despised prisoner had come a long way. He was also granted an official title straight from some 1930s sci-fi potboiler, he was the Chief Designer of Spaceships. His personal details were made state secrets; even his name was unknown in the West until after his death. During the early 1960s, Korolev was eager to send a Soviet cosmonaut to the Moon. By a methodical approach he hoped to achieve a Soviet lunar landing before the Americans. The first flights of the Vostok spacecraft would prove that human space flight was possible. In 1961, Korolev's team had another brilliant success with the flight of Yuri Gagarin in Vostok 1. Vostok would be replaced by a more advanced multipurpose craft, Soyuz. Meanwhile, the largest rocket ever built, the N-1 would be developed to boost cosmonauts to the Moon or launch mighty space stations into orbit. The future looked bright for Korolev's dreams of space conquest. Sadly for Korolev things did not work out this way. His attention was diverted as he was pressurized by his superiors to develop space propaganda stunts, such as the risky Voskhod missions, to up-stage the Americans. Developing the Soyuz and N-1 was more difficult than anyone expected (the N-1 was eventually abandoned

"the R-7 was a huge missile capable of delivering a nuclear warhead"
In October 1945, he was allowed to visit the now defeated Germany to observe Operation Backfire, a British sponsored demonstration of captured A4 rockets (the A4 is much better known by the nom de guerre V-2). Korolev was later involved in collecting captured enemy rocket hardware and technicians to aid Soviet missile research. Initially the Soviets copied their former enemy's work, building replica A4s as R-1s and developing the more advanced R-2 and R-5. By the early 1950s Korolev was a rising star, leading the research organization responsible for long range rockets. Abandoning the now out-moded German technology, Korolev was developing the R7, a huge missile capable of delivering a nuclear warhead to a target in the US. However, Korolev had nobler goals than facilitating Armageddon, he saw the R-7 (often referred to in older books by the NATO designation SS-6 Sapwood) as the world's first space rocket. As early as 1953 he suggested that his creation could be used to send a satellite into orbit. Aware of the American effort to achieve this, he was allowed to develop this dream with historic results. As a reward, a jubilant Politburo gave Korolev extra funding to develop planetary probes and

Tribute to the Chief Designer This Soyuz launch vehicle has a portrait of Korolev painted on the external payload fairing. He would have celebrated his 100th birthday shortly before this rocket launched the Progress 24 vehicle in early 2007.

Image Credit: NASA


8 Astronotes October 2007 after several spectacular explosions). Finally Korolev became the subject of bitter rivalries in the Byzantine Soviet space bureaucracy. He may have overcome these problems in time, but sadly Korolev died in murky circumstances when a routine surgery went terribly wrong in 1966. Korolev was married twice and had a single child, a daughter. Unusually for a Russian man of his time he was only a moderate drinker. In manner he could be cynical and unapproachable, but was respected by those who worked for him. Today his contribution to space exploration is undoubted. The Soyuz spacecraft he conceived is still carrying people into space forty years after its first flight. The mighty R-7 proved too unwieldy and delicate to be a useful weapon and was rapidly replaced by more advanced missiles. As a space launcher it was as good as Korolev intended and it is still in service today as the Soyuz Launch Vehicle. More than 1700 of these have been built, more than any other launch vehicle. Korolev would be pleased with his legacy.

The Planetarium's EHOD
By Wendy McCorry, Science Communicator This year marks the tenth anniversary of Northern Ireland's European Heritage Open Days (EHOD) event run by the Environment and Heritage Service. EHOD is an annual celebration of local buildings and culture, during which individuals and facility-owners all over Europe open their doors to the public free of charge. This year's event took place on Sat 8th and Sunday 9th September, and was the first year in which Armagh Planetarium took part. Due to the success of the event, however, it is unlikely to be the last. The planetarium opened its doors free of charge to visitors from 7pm-9pm on Saturday 8th September, with a show in our digital theatre taking place at 7.30pm. The show on offer was our ever-popular live show, Pole Position (Summer Skies), in which the presenter takes the audience on a live tour around some of the most fascinating objects in the current night sky. Here at the Planetarium we operate a pre-booking system to ensure that everybody is allocated a seat in the theatre, and nobody is disappointed on arrival. In the days prior to the event it soon became clear that demand for the show was very high, with another showing having to be added to the schedule to satisfy demand. Many canny people coupled an afternoon tour of the Armagh Observatory with a later visit to the Planetarium ­ a whole day of astronomy! On the evening itself we were inundated with visitors, and actually ended up running three live shows back to back! The audience thoroughly enjoyed the shows and feedback was very positive. In all, 198 visitors came through our doors in one evening. Our hope is that this event has encouraged those people to come to the planetarium who perhaps would not usually think of visiting us. We also hope that those who came, as with all the other EHOD sites, do not wait until next year's event before they visit us again!
Image Credit: EHOD

EHOD logo Sites nationwide opened specially for this annual event.


October 2007 Astronotes 9

COS-B: our new display
By Tom Mason, Director Armagh Planetarium has just installed a new exhibit on the ground floor. It is a real satellite, but it has not flown in space, as it is a bit tricky (and hugely expensive!) to recover them once they have been launched. It was also a bit of a squeeze getting it through the doors, they had to come off! It is an engineering model of the COSB spacecraft. The "real" COS-B spacecraft was flown by the European Space Agency (ESA) in August 1975. The satellite was launched as the payload of the very reliable US-designed Delta 2913 rocket. Engineering models are exact replicas of the satellites that are flown into space. In the current generation of robotic space craft, they are used to test programming instructions and to run other diagnostic checks that are best proven on the engineering model on Earth. This means that if there is a programming error, it can be detected on the model and corrected before the programme is uploaded to the space craft while it is flying its mission. This can prevent irreparable damage or fatal programming errors being sent to the craft after it has been launched and the only communication is electronic. These models also are used to check that all of the satellite's components fit together in a mechanical engineering sense, as well as allowing testing of all the electrical interfaces that are in the spacecraft's nervous system. COS-B above Earth ESA's Cos-B, launched 9 August 1975, provided the first complete galactic survey in high-energy gamma-rays. Before this, the gamma-ray Universe had largely been invisible to astronomers. act as umbilical connections that allow ground controllers to check the health of the satellite's systems just before launching from the parent ship. Obviously on the actual satellite flown into space some of these connections would not be present, as there is no one in space to attach computers or other bits of hardware. Our COS-B model has had two banks of its solar panels removed and replaced with Perspex allowing visitors to see inside. The solar panels look like they are made up of small blue mosaic tiles which cover the outside of the cylindrical body of the satellite. Visitors can see that they have lots of small wires that connect them all together; this means that they all act in concert to convert sunlight into electrical energy which is used to power the satellite's systems. This works well in those craft that are relatively close to the Sun, but when exploration probes need to travel far from the Sun there are other ways of powering such spacecraft, including small nuclear reactors.

"Our COS-B has had solar panels removed allowing visitors to look inside "
It was only in 1983 that the ESA EXOSAT craft was flown with an on-board computer. On the Planetarium's COS-B model you can see the RS232 connectors that would have been used in this model to allow the electrical test harnesses to "talk" to the spacecraft's systems. They also

Image Credit: ESA


10 Astronotes October 2007 The satellite's cylinder is divided into two bays, upper and lower. The upper bay has had its heart removed. It was a gamma ray detector and would have been fitted in the centre of the upper bay. The top of the satellite would have been a very thin membrane rather like aluminium cooking foil which would allow gamma rays to pass through and to be detected by the instrument beneath. On the concave underside, the actual spacecraft would have had a big golden-coloured ring. This would have been used to mount the satellite in the payload bay of the Delta rocket launch vehicle. Once it was in space and ready to be inserted into its orbit, or flight path, explosive bolts would have been fired on command from the Earth tracking station. This would allow the satellite to be freed of the final stage rocket motor and thus launched into orbit on its own. This craft also has very simple attitude controls. Small conical nozzles are mounted on the base and on the equator of the cylindrical satellite; the attitude of the satellite can be adjusted by allowing gas to escape from them in controlled bursts. In this particular design its orientation was less critical than many modern satellites which do not have solar panels all the way around the outside of the craft. The gas fuel for the attitude thrusters was contained in the shiny cylinders in the same way that Calor gas is supplied in a pressure vessel. As the amount of gas needed to adjust the attitude would normally be very small such supplies would last for some time. Basically, once the gas supply was exhausted, the satellite would have reached the end of its useful life, and it would be allowed to slowly descend under the pull of the Earth's gravity. Once it starts to interact with the upper layers of the atmosphere, the satellite's orbit becomes more unstable, and if it is small enough it burns up in a spectacular fireball as the atmospheric friction heats and burns the fabric of the craft. The wiring harnesses that can be seen inside the body of the craft were designed with redundancy in mind. Thus, if one system fails, another can be used to make sure that the lifespan of the satellite and its experimental payloads are not cut short by something as elementary as a simple short circuit. This means that each of

COS-B arrives The `launch vehicle' was a forklift, the `Payload Shroud' a wooden crate. the boxes in the upper bay is connected to its neighbours by more than one electrical route. In spacecraft it is usual to have triple systems to provide a greater degree of redundancy. Designers need to be aware of the possibility of small meteoroids puncturing the skin and damaging the wiring: they also exploit the potential of using the bulky items to shield more vulnerable parts of the craft's innards. In the Planetarium display we have added some lights to make it easier to see the structures on the inside walls and to highlight the wiring and other elements of the design. This display demonstrates how you do not have to be an astronaut to work in the exploration of space. This craft will need: scientists who are familiar with the physics of gamma rays and how to detect and count them; engineers to design and build the electrical and mechanical parts of the craft; mission specialists to track and communicate with the rocket and the satellite when it is launched; specialists who understand how to design small reliable systems, and how to best package them so that they are mutually dependent, while still being able to work on their own if necessary; computer programmers and software engineers who provide the pathways that allow the systems to talk to each other, and to Earth. This means that there is the need for lots of different talents in the space business. If you are properly motivated, and well qualified, this could be you.

Image Credit: Colin Johnston, Armagh Planetarium


October 2007 Astronotes 11

Toulouse's City of Space
By Colin Johnston, Science Communicator If you visit the lovely French city of Toulouse, it is possible to explore the Universe in the same visit! Established in 1997, CitИ de l'espace is a visitor attraction dedicated to educating the public about space exploration and astronomy while entertaining them at the same time. Set in a 3.5 hectare (over 8.6 acre) landscaped park outside Toulouse, the centre features three modern and attractive major buildings including a large main exhibition hall and a planetarium. However they are overshadowed by the major exhibits outside; there are large models of the planets of the Solar System, interactive displays of basic astronomical principles and realistic mock-ups of space hardware. Visitors can walk around the exterior of a full-size replica of the Mir space station before filing though its cramped interior. Above it looms the impressive bulk of an Ariane 5 launch vehicle on its pad. and English. The 280 seat planetarium features a Digistar 3 system using twelve projectors to cater for the large 20m tilted dome. On the day of our visit, the show playing was Evans & Sutherland's `Stars of the Pharaohs' .The show also featured an extensive live night sky presentation making up a running time approaching an hour. There is a separate IMAX theatre in the same buildAriane 5 The full-size ing, although we gave it a replica dominates the miss as there was much local skyline more to see. CitИ de l'espace is well worth traveling to if you are in south west France. I suggest that you set aside at least half a day for your visit. There are restaurants and a cafИ, and a well-stocked shop. As many of the attractions are outdoors, be prepared for whatever the weather has in store. (More information is available from http://www. cite-espace.com/content/gb/)

"I enjoyed flying around the ISS on a jetpack"
Inside the main exhibition space which is spread over several levels, visitors can take their own time to examine the many genuine artifacts related to European space exploration. Toulouse is a major centre for the flourishing French aerospace industry ­ it is home to Airbus among other companies ­ and CitИ de l'espace has clearly benefited from this connection. The display of rocket engines is particularly impressive. The focus is on astronautics, but astronomy is not neglected. There are many `hands-on' or computerised demonstrations of spacecraft operation and astronomical observations. These are suitable for all ages and can be a lot of fun- I especially enjoyed `flying' myself around a virtual ISS on a jetpack! Most exhibits have multi-lingual explanatory placards and headsets providing an audio commentary in English are available at reception. There are regular guided tours of the centre, and these are conducted in French

Mir mockup A steady stream of visitors tour about the repliica of the historic space station .

Image Credit: Colin Johnston (both images)


12 Astronotes October 2007

Image of the Month
The star Mira (Omicron Ceti) has amazed astronomers for centuries; its name actually means `the Amazing One'. Mira is an extraordinarily variable star. Every 330 days its brightness in our skies ranges from a prominent second magnitude to a dim tenth magnitude- too dim to be seen with the naked eye (it is near the low end of its cycle at the moment). Mira is an old red giant, no longer steadily generating energy through nuclear fusion. Instead it is running in fits and starts, blasting off material, mainly hydrogen but including other elements such as oxygen and carbon, from its outer layers. Mira is about 420 light years (130 parsecs) from the Sun and is orbited by a small companion star, Mira B. Mira B is itself surrounded by a disc of material, either material `donated' by its giant partner or its own protoplanetary disc. Recently we have discovered that Mira is even more marvellous than previously believed. This is an ultra-violet view of Mira from NASA's Galaxy Evolution Explorer (Galex) space telescope. Images from GALEX have shown that Mira has a tail about 13 light-years in length like that of a vast comet. The tail has formed over the last 30 000 years as the star sheds its outer layers. At the same time, Mira is moving through the incredibly tenuous interstellar medium- space is not quite empty- at the very high speed of 130km/s (about 80 miles per second). The interstellar medium is composed of gas and dust particles spread so thin as to be all but a perfect vacuum. Even though it is so insubstantial, the interstellar medium is the cause of Mira's extraordinary tail. Scientists believe that as Mira punches through it, the wisps of gas are compressed and heated into a shock wave of plasma in front of the star. Mira leaves a turbulent wake behind it as it travels and the energized gases in this twisted tail radiate ultra-violet as it goes.
Image Credit: NASA/JPL-Caltech

Mira's days as a `proper' star are numbered, in a cosmic eyeblink, it will lose its outer layers entirely. These will form a beautiful planetary nebula with a tiny white dwarf at the centre. Mira will spend trillions of years as a white dwarf. Looking further into the very distant future, Mira's stellar corpse will gradually melt away to nothing as the very protons in its atoms decay.But don't worry, we will still be able to wonder at amazing Mira for millenia to come. (Caption by Colin Johnston, Science Communicator)

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 ©2007 Armagh Planetarium All rights reserved