Wadhurst Astronomical Society Newsletter July 2014

MEETINGS

COMMITTEE MEETING Members of the Committee are respectfully reminded that there is a meeting on Tuesday July 1st starting at 0730 in the usual place.

JUNE MEETING This meeting was our Open Evening which we always hold on the nearest meeting to the Summer Solstice when the days are longest and the skies are bright for so much of the night. It was open free to all visitors to encourage an interest in astronomy. There were many telescopes present, amongst them was a computerised 6-inch Schmidt- Cassegrain on an alt-azimuth mount brought by John Wayte who also had with him a large pair of 20 x 80 Revelation binoculars on a tripod and his Meade Sky Guide containing a database of over 30,000 objects.

John Wayte’s 6-inch Meade Schmidt-Cassegrain and Sky Guide John Vale-Taylor’s incredible telescope for the disabled

Phil Berry’s Megrez 80 Refractor on an Astro Track pier John Vale-Taylor brought his innovative “wheel chair” telescope he had made using his experience in engineering and design. This is a telescope through which one can view the night sky from a sitting position and without having to move. It also included an ingenious finder scope.

Phil Berry had with him a number of amazing telescopes such as a Megrez 80 appro refractor with a William Optics 20 mm eyepiece and using Robo-focus. This telescope was mounted on an Astro Track pier ideal for the serious astro-photographer on the move. He had also brought a 60ED Zenithstar refractor (ED – Extra low Dispersion) also with a polar-scope mounted for demonstration. In addition he had with him stabilising binoculars and a Coronado PST (Personal Solar Telescope). Following recent storm damage to the church of St Peter and St Paul it was suggested that a ‘Time capsule’ containing an account of life today in Wadhurst should be installed in the church following repairs to be opened in 100 years time. The Society was approached for an inclusion of something about the Wadhurst Astronomical Society. Phil has compiled a piece that includes a photograph of members taken at the meeting and is shown in full at the end of the Newsletter. Our Director of Observation was then introduced to give his talk. Introduction to Astronomy Brian Mills To begin his talk Brian said there are certain questions asked of an amateur astronomer: Is there life on other planets? How far are things away? And they nearly always ask how much did your telescope cost? We are all familiar with distances on Earth with but Brian began to look further afield with how we measure distances in space. The distance from the Earth to the Sun is 149,598,261 km which is in a metric unit of measurement we are all familiar with but this is cumbersome when we talk about the Solar System where we more usually use the Astronomical Unit, the AU; the distance from the Earth to the Sun. On this scale the distance to the Moon is 0.0025 AU, Saturn is 10 AU from the Sun, Uranus 20 AU and Neptune 30 AU. This is ok for the Solar System but greater than this we use the speed of light, 300,000 km per second as our measuring stick. The nearest star after the Sun is Proxima Centauri; the light from this star takes just over 4 years to reach us so we say it is 4 Light Years away and the next, Barnard’s star is at a distance of 6 light years. Another unit Brian referred to was the Parsec although this is usually only used in scientific papers. If the position of a star is recorded from Earth and then its position is measured 6 months later in its orbit the nearer stars would appear to have moved relative to the background stars. If this angle divided by 2 has changed by 1 arc second; 1/60th of one arc minute or 1/3600th of one degree then we say the star is 1 parsec away which is also 3.3 light years. Now Brian turned to the question of what the Earth is made of although as he said quite a lot of the interior of the Earth is of a plastic nature rather than solid.

The interior structure of the Earth

The average diameter of the Earth is 12,734 km but because of centrifugal force the polar diameter is 12,712 km and the equatorial diameter is a little more at 12,756 km. We looked next at the Earth’s atmosphere. The lowest 20 km is called the Troposphere and contains 80% of our atmosphere and the temperature towards the higher part reaching as low as -60° C. At the top of the Troposphere, we come to the Stratosphere which continues up to 50 km with a temperature rising to about freezing due to Ultra Violet absorption. The Mesosphere is next, reaching to 85 km above the Earth’s surface and is where meteors burn up and any water vapour forms Noctilucent clouds. The temperature here can be as low as -100° C. The next layer, up to 690 km, is the Thermosphere with temperatures reaching 1,500° C. The lower part is where Auroras occur and further up is the orbit of the International Space Station at about 400 km. The fact that there is still a slight atmosphere here means that every now and then the station requires a boost to overcome atmospheric drag. Finally, up to 10,000 km is the Exosphere containing mostly hydrogen and Helium and we were told that the particles here are so far apart, they almost never collide.

Brian looked at how the Moon was formed. He said the most popular theory at present is that in the distant past the Earth was struck by a Mars sized body subsequently given the name Theia. The resulting strike may be why the Earth’s axis is at an angle to the plane of the Sun but this does give us the seasons. The phases of the Moon we see were explained and we were told that the best time to see the Moon’s craters is not when light from the Sun is full on but is at an oblique angle, revealing the walls of the craters by their shadows. One face of the Moon is always directed towards us but due to the Moon’s elliptical orbit around the Earth, there are times when it travels faster or slower and this enables us to see a little bit more round the side. Also, because the plane of the Moon’s orbit is not the same as the Earth’s, at times we are able to see a bit more of the Moon’s north or south polar regions. This oscillation of the Moon as we see it from Earth is called Libration. Brian presented a short explanation of a lunar eclipse and gave the reason why the Moon sometimes appears deep reddish in colour due to light from the Sun passing first through the Earth’s atmosphere. He also explained the difference between a total Solar eclipse, when the Moon is closer to us and an Annular eclipse when the Moon’s orbit takes it further away and is visually smaller leaving a bright annular ring. This was followed by a quick explanation of the effect of the Moon’s gravity on the fluid oceans and to a lesser extent by the Sun’s, causing the tides. We were introduced to the interior of the Sun where the core is 15M° C; hot enough to fuse hydrogen and helium at the rate of about 500 million tons a second. Surrounding this is the Radiative Zone and further out, the Convection Zone a 2M° C. Then there is the Photosphere at 6,000° C which is what we see. Surrounding this is the Chromosphere at 20,000° C which we see during a total eclipse, and finally the Corona at 2 to 3M° C. Brian very sensibly warned against looking directly at the Sun without any eye protection. The human eye can be permanently damaged by direct sunlight in an instant. and advised using a Mylar filter or projection methods Brian completed his description of the Sun by talking about sunspots which he said occur in a pattern over an 11-year cycle. Early in the cycle, sunspots form in the higher latitudes but as the cycle progresses, they appear closer to the equator. He showed a graph of sunspot latitude against time, known as the Butterfly Diagram because of its appearance.

The Butterfly diagram - NASA The graph shows the difference in activity over many years. We looked at different stars compared with our Sun. Two particular stars in the constellation of Orion are good examples. Rigel is the brightest in the constellation but compared in size, red Betelgeuse is by far the largest. We were told that Betelgeuse is predicted to become a super-nova soon and at 640 light years away, may already have done so, although the light hasn’t reached us yet. On the same size scale by comparison, the Sun is so small it is almost lost. Brian then looked at the bigger picture starting with the Milky Way of which the Solar System is only one tiny component. Our galaxy contains between 100 and 400 billion stars, is about 1,000 light years thick and something like 100,000 light years in diameter. The most distant object we can see with the naked eye is our neighbour the Great Andromeda Galaxy which contains an estimated one trillion stars.

The Great Andromeda Galaxy M31 - NASA Hubble Extreme Deep Space image - NASA And finally we looked at a picture taken by the Hubble Space telescope called the Hubble Extreme Deep Field with a visual area that could be represented by a grain of sugar being held at arms length but containing something like 200 galaxies. That, as Brian said is just one tiny part of the whole Universe. Imagine the number of stars that must include! More about this image in the NASA SpacePlace article later in the Newsletter. Lastly Brian introduced a number of examples of telescope used in astronomy, most of which were present at the meeting. German Equatorial Mount Alignment - GEM Phil Berry Many amateur astronomers now own German Equatorial Mounts to enable their telescope to follow the movement of the night sky and with this in mind; Phil went through the alignment of the GEM mount belonging to the Society and available for members to borrow complete with a very good 4-inch Konus refracting telescope, two eyepieces and a Barlow lens. He began with the theory of why we use a GEM to cancel out the Earth’s rotation so that the telescope always follows the apparent movement of a star. If one takes a long exposure image of the night sky with a static still camera the stars have trails and this movement is what is cancelled out. Phil showed a long exposure photograph taken with a static camera and the trails appeared as concentric circles with the north celestial pole at the centre, which is one of the alignment points for the mount. Orientating the tripod is the first thing to be done. The Society mount has an ‘N’ label and this faces north leaving one of the tripod’s legs towards the south. Phil said doing this greatly helps during the alignment. The length of the tripod legs is dictated by where the eyepiece will be. With a refractor, this would be at the end of the tube and viewing something overhead would mean having the legs out longer, bringing the eyepiece to a more convenient height. With a reflecting telescope, the eyepiece is not so much of a problem and the legs can be shorter. The legs are held rigidly apart by an accessory tray mounted between them and beneath the head. This is an ideal position to place a spirit level to ensure that the mount is level having first ensured that the feet are firmly on the ground. The angle of the head needs to be corrected for latitude which is 51° at Wadhurst and the surrounding region. To enable this part of the alignment there is an adjustment at the base of the head which uses a couple of clamps.

Having shown how to find Polaris the pole star the polar alignment can begin, enabling the polar axis of the mount to point to the north celestial pole. Phil told the meeting that there is a polar scope, the top and bottom of the mount’s polar axis have removable

screw-on caps and removing these reveals the polar scope. At night, by looking through the polar scope it is possible to accurately align the mount. This means bending down to look through the eyepiece during the alignment and Phil showed a much less back-breaking method, using a green laser shining through the polarscope and doing the alignment that way; adding a warning to be aware of any aircraft that could be dazzled. The weight that the mount has to carry should be as balanced as possible and to facilitate this there is a bar to take a counter-balance weight. This slides onto the bar towards the top end to prevent the tripod from toppling over before the telescope tube is attached and then temporarily tightened for the time being. Phil said it is important to replace the large at the lower end of the bar to stop the weights from accidentally sliding off; this screw is called a ‘toe saver’. Now for attaching the telescope tube complete with eyepiece and finder. With the Right Ascension control towards the observer, the tube is mounted and clamped for the time being in the cradle. Loosening the clamps slightly, the tube can be slid in the cradle to a position where it is balanced with the Declination lock loosened. Once balanced the cradle clamps are tightened and the Dec. lock can also be re-tightened. The weight of the telescope is balanced with the counter-weights to prevent strain to the head by loosening the Right Ascension lock, RA, and adjusting the counter weight until the telescope is balanced, remembering to tighten the weight and re-tightening the RA lock. Another of Phil’s useful tips was to consider where the telescope will move during an observing session. After time, it is possible that the telescope may reach a position where it can begin to catch on part of the mount, then what is called a ‘Meridian Flip’ is used where the mount is swung round, still looking at the same object and still retaining the mount’s alignment. The Society telescope is manually driven but with electrically driven drives this limit can be met without the observer being aware. Phil described how to line up the finder with the main telescope, starting in daylight and using a low magnification eyepiece in the telescope; one with a higher mm rating. Then line up the main telescope on something at some distance away such as a chimney corner and then adjusting the finder so that the chimney corner is at the centre of the finder’s cross hairs. Using a higher magnification eyepiece, make finer adjustments. But the final adjustment will need to be done at night with a bright star which is as far away as one can get so that parallax is at a minimum. Phil did mention ‘drift alignment’. After a time, it may be found that a star isn’t being quite so accurately tracked. This can be compensated for by slightly adjusting the alignment and so producing an even more accurate alignment. He then wished observers the best of viewing. A request for suggestions for future activities of the Society At the close of the meeting, the Chairman, John Vale-Taylor thanked Brian Mills for a booklet free to everyone and containing a summary of the introductory talks Brian has given to the Society on the Solar System over the past few months and contains a lot of very useful and fascinating information. John then went on to ask what members would like at future meetings. Quite a few very useful suggestions were made, such as wanting to hear more about satellites and what is up there. Another was to learn more through short talks on the use and purpose of astronomical filters. This was followed by a discussion about trying to arrange some practical observing evenings which would be pre-arranged and taking a chance, as always, on the weather although the area around our meeting venue was thought to be too light polluted. A show of hands indicated that well over half of those present were interested in taking part in observing sessions. One suggestion was that we had a short talk on the use of Stellarium, the free internet programme. Another suggestion was to take part in a Citizen Science Project. More recently, a number of internet based science projects are becoming popular, one being ‘Zooniverse’ where home computers are increasingly being used on a global scale to provide huge amounts of data from a number of science subjects such as neuroscience, medicine, zoology, the humanities and astronomy. These suggestions will be discussed by the Committee.

JULY MEETING

Wednesday 16th July – Our Chairman John Vale-Taylor is giving a talk he calls “Antique Cameras to Telescopes” Meetings begin at 1930 although members are invited to arrive anytime after 1900 as this is a good time to exchange ideas and discuss problems and also relax before the meeting starts. The venue as always is the Upper Room of the Methodist Church at the east end of Wadhurst Lower High Street, almost opposite the entrance to Uplands College. (For those with SatNav – the post code is TN5 6AT) Anyone is welcome but non-members are asked if they wouldn’t mind contributing £3 towards costs.

FUTURE MEETINGS Saturday 30th of August - we will be holding our annual barbecue. This will be in the Wadhurst area and details will be in the August Newsletter. Wednesday 17th September – John Lutkin gives a talk he calls “Infinity and Beyond” and are some random thoughts on mathematics in astronomy, Wednesday 15th October – Jan Drozd is giving a talk on “My First Steps in Planetary Imaging”.

SKY NOTES FOR JULY 2014 Planets Mercury is a morning object reaching greatest western elongation on July 12th. Despite the planet being 21° from the Sun, it is very poorly placed as seen from the UK. On that day, with the Sun 6° below the horizon, Mercury is only 4° high in the east-north-east making it a very difficult target, particularly as it’s magnitude is only +0.5. However, Venus is only 7° to its north east and much brighter so it will act as a guide to its fainter companion. However, if you wait until July 25th Mercury will still be 4° above the horizon but has now brightened considerably to magnitude -1.1. Its position is shown on the map for the 25th at 04.30 BST.

Venus is a morning object visible low down in the east-north-east at magnitude -3.8. At the start of the month the planet rises 1½ hours before the Sun and has reached an altitude of 15° by sunrise. By month’s end Venus is 17° above the horizon with the Sun rising two hours later.

The phase of the planet increases during the month but its apparent diameter is dwindling. The reason for this is that Venus is heading towards a superior conjunction in October when it will pass behind the Sun and will be at its furthest from us and of course appear at its smallest. This can be seen from the diagram above. The only time that Venus is fully illuminated is when it is behind the

Sun and of course invisible to us. After conjunction the planet moves gradually eastwards presenting initially a gibbous phase, then dichotomy (50% illuminated) followed by a crescent. All the time its apparent size has been increasing as it draws closer to us. Ultimately it is largest when it lies between us and the Sun when its dark face is turned towards us. It is at such times that, if conditions are right, we see a transit of Venus across the solar disk. Earth reaches aphelion (our closest to the Sun) on July 4th at 01.13 BST. Mars is visible at an altitude of 25° at sunset on the first day of July. It moves eastwards through Virgo during the month and is 1½° north of Spica on the 12th. As well as travelling direct (west to east) it also moves lower in declination making it a slightly more difficult target. The first quarter Moon is 2½° south west of the planet on the 5th.

Mars can be found by drawing a curved line through the end stars in the handle of the plough and continuing it through the bright star Arcturus and on to Spica. I have indicated the position of Mars on the first and last days of the month as it is moving comparatively briskly. Mars was at opposition on April 8th, so the Earth has been moving ahead, and away, from of it for three months. The result is that its angular size is only half what it was when it was at its closest (8 arc seconds compared to 15.2 arc seconds) and the planets magnitude has also decreased from -1.5 to +0.3. There will be no opposition of Mars in 2015 because it has a synodic period which is, on average, 780 days although this can vary between 765 and 800 days. The synodic period in this particular case is defined as the length of time between successive oppositions. In general terms it refers to a body returning to the same position relative to the Sun as viewed from Earth. The next oppositions of Mars will occur on May 22nd 2016, July 27th 2018 and October 13th 2020. Of these the best will be the 2018 event when Mars will have an apparent size of 24.2 arc seconds and a maximum magnitude of -2.8. Jupiter is now too close to the Sun for observation, passing behind the Sun in conjunction on July 24th and then emerging into the morning skies during August. It will become an evening object once more towards the end of October. Saturn is still well positioned in the late evening sky being on the meridian at sunset at the beginning of the month. The planet is moving retrograde until it reaches its second stationary point on July 20th after which it resumes direct motion (west to east). Unfortunately Saturn is not particularly high in the sky at the moment, culminating at an altitude of 24° and then of course descending towards the horizon. The best images are likely to be taken with web-cams and planetary cameras that can “freeze” the atmospheric turbulence that causes problems at low altitudes. The position of Saturn is shown in the Mars section above. An alternative way to find Saturn is to start with the two stars in the rear of the bucket of the plough and draw a line through them and continue it in the general direction of the horizon. It will bring you to a back to front question mark that is the “sickle” of Leo. Once this has been found you will be able to identify the rest of Leo and use the two stars in the lion’s hind quarters to direct you approximately towards Saturn. This method is demonstrated in the map below.

Lunar OccultationsIn the table below I’ve listed events for stars down to magnitude 7.0 that occur before midnight although there are many others that are either of fainter stars or occur at more unsociable hours. DD = disappearance at the dark limb. The column headed “mm” (millimetres) shows the minimum aperture telescope required for each event. Please remember that the Society has telescopes that members can borrow, all of which are suitable for the such events. Times are in BST.

July Time Star Mag Ph Alt ° % illum. mm 2nd 21.58 SAO118471 7.1 DD 12 26 80

7th 21.44 ZC2105 6.3 DD 22 74 70 Phases of the Moon for July

First ¼ Full Last ¼ New 5th 12th 19th 26th

Meteors The Perseid meteor shower begins on July 23rd and is active until August 20th with maximum occurring on the night of July 12th/13th. The Moon will interfere considerably during August. . ISS There are no evening passes of the International Space Station (ISS) during July although there are a large number that take place after midnight. Details of these can be found at:- www.heavens-above.com Iridium Flares The flares that I’ve listed are magnitude -2.0 or brighter although there are a lot more that are fainter or occur after midnight. If you wish to see a complete list, or obtain timings for somewhere other than Wadhurst, go to www.heavens-above.com . Remember that when one of these events is due it is sometimes possible to see the satellite before and after the “flare”, although of course it will be much fainter at those times. Times are in BST. There are a number of events that are extremely bright, particularly those on the 11th and 25th both of which occur at very respectable altitudes.

July Time Mag. Alt° Az.° July Time Mag. Alt° Az.° 3rd 22.42 -7.4 38 39 (NE) 17th 23.14 -2.2 25 29 (NNE) 5th 22.33 -2.5 42 40 (NE) 18th 21.34 -6.2 60 54 (NE) 6th 22.28 -3.4 42 41 (NE) 18th 23.08 -4.4 25 31 (NNE) 11th 22.06 -8.0 50 47 (NE) 20th 23.03 -6.9 29 35 (NE) 11th 22.07 -2.1 51 46 (NE) 22nd 22.53 -3.0 33 38 (NE) 12th 22.01 -3.6 51 48 (NE) 23rd 22.47 -3.2 33 39 (NE) 13th 23.28 -2.9 17 22 (NNE) 25th 21.01 -8.4 70 66 (ENE) 14th 23.22 -4.0 18 24 (NNE) 27th 22.33 -3.6 40 44 (NE)

The Night Sky in July (Written for 22.00hrs BST mid month) In the north the bright star Capella is just skirting the horizon and approaching the meridian whilst above the north celestial pole Ursa Minor stretches towards the zenith. The head of Draco lies close to the overhead point allowing the twists and turns of the dragon to be more easily followed. At one point Draco’s tail passes between the two bears, with one of its stars being of special note. This is Thuban, which 5,000 years ago had the honour of marking the north celestial pole, and will again 26,000 years after it initially did so. Due to precession, the Earth’s north and south poles describe an imaginary circle in the sky that, for northern observers, will pass through Cepheus, Cygnus and Lyra until in 12,000 years time the accolade of “Pole Star” will belong to Vega. Sadly, it will always be more than 5° from the celestial pole proper. See the diagram below which shows one full rotation. With Ursa Major lying to the west of the pole it follows that Cepheus and Cassiopeia will be found to the east of it. Perseus is rising but not yet clear of the northern horizon, although the double cluster in the “Sword Handle” is at an altitude of more than 20°. Looking east we see that old favourite, the Summer Triangle, is already well positioned with the brilliant Vega 65° above the horizon and the body of the celestial swan lying parallel to the horizon. Cygnus has its fair share of open clusters with M39 (mag 4.6) and NGC 6871 (mag 5.5) being the brightest. It is also home to the well known and much photographed Pelican and North America nebulas. If colourful doubles are your thing then you will already have admired that lovely blue/yellow combination that is β Pegasi better known as Albirio. The brightest star in the constellation is the celestial beacon, Deneb, that lies some 3,200 light years distant and shines with the power of 250,000 Suns. Below Cygnus lies Vulpecula, a small constellation with no stars brighter than magnitude four and no identifiable shape. There are several magnitude six open clusters plus the Dumbbell nebula (mag 7.6) and the Coathanger asterism that all lie within its borders. At this time of year the southern part of our sky is almost devoid of bright stars with the area given over to the generally faint star groups of Serpens, Ophiuchus, Hercules and Libra. From the latitude of the UK Sagittarius and Scorpio are never well placed for observation. Just above the southern horizon Scorpio straddles the meridian with the orange-red supergiant, Antares, at an altitude of 12°. Its size is such that if it were to replace our Sun, it would reach out to between the orbits of Mars and Jupiter. A slow variable, it has a mass of approximately 16 to 17 solar masses. Due to its location close to the ecliptic it is subject to occultations by the Moon, although the next such event won’t occur until the year 2,400. To the east of Scorpio lies Sagittarius, with its “Teapot” asterism, that will be at its best at the end of July. In the west, Leo is about to set, with Virgo soon to follow. Arcturus is still more than 45° above the horizon meaning that Corona Borealis is well placed for those who follow the fluctuations of T CrB, a recurrent nova, and R CrB, a rare type of irregular variable. A line drawn from Arcturus, through Alphekka, the brightest star in Corona Borealis, and onwards will find the “Keystone” in the faint constellation of Hercules.

Wikimedia Commons image by Tau’olung, Tonga Towards the end of July we regain a period during the night when we are once more free from twilight. True darkness is defined as the period when the Sun is more than 18° below the horizon. This happens initially around 01.00 on the morning of July 21st. At such times, particularly from a dark location, the Milky Way can be a superb sight as it arcs across the sky. Of course it isn’t only at such times that the Milky Way is visible, the area around Cygnus for example is obvious to Perseid meteor watchers on moonless nights. During July the band of stars stretches from Sagittarius on the southern horizon, through Aquila, Cygnus and Cassiopeia until it reaches Perseus on the northern horizon.

Advance warning for August 18th - Jupiter and Saturn just 12 arc minutes apart in the morning sky. What Objects Can I Look For This Month? 1. Double cluster in Perseus. This is, as its name suggests, a pair of open clusters in the sword handle of Perseus that are designated NGC 884 and NGC 869 and are both roughly ½° across, or the same size as the full Moon. NGC 869 contains approximately 200 stars whilst NGC 884 has around 150 members. They are a superb sight in binoculars or a wide field telescope, particularly when seen against a perfectly dark sky. The pair are easy to find if you use two of the stars in Cassiopeia as a guide. Draw a line from gamma (γ), through delta (δ) and on towards Perseus for twice the distance between those two stars. See the diagram below left.

2. Double star Albireo This is one of the nicest of double stars where the components are of different and contrasting colours. Albireo is at the head of Cygnus the swan and is otherwise known as Beta (β) Pegasi, although this is a misnomer as it is the fifth brightest star in the constellation and should more correctly be designated epsilon (ε). Of the two stars Albireo A is orange and magnitude 3.1 whilst 35 arc seconds away Albireo B is blue-green and fainter at magnitude 5.1. You will need good binoculars or preferably a small telescope to see this double well. See the diagram above right. Astrophotography Evenings We did try to organise some of these evenings earlier in the year but the weather on more than one occasion was dreadful. At the Society meeting on June 18th members present indicated that they would be interested in having another try at taking some stellar images. The plan would be for the Society to make available some moderately robust equatorial mounts to carry a number of members digital single lens reflex cameras (DSLR’s) and take some multiple wide angle, possibly Milky Way, images. Of course if members had mounts of their own then they could use them instead. This would be followed by another evening when we would process them together with help from our own Ian King who has offered to attend to give us the benefit of his enormous experience in such things. If you are interested please let me know using the e-mail address at the end of the Newsletter. These evenings will only go ahead if we get sufficient interest from members (or non-members).

NASA SPACE PLACE A Glorious Gravitational Lens By Dr. Ethan Siegel As we look at the universe on larger and larger scales, from stars to galaxies to groups to the largest galaxy clusters, we become able to perceive objects that are significantly farther away. But as we consider these larger classes of objects, they don't merely emit increased amounts of light, but they also contain increased amounts of mass. Under the best of circumstances, these gravitational clumps can open up a window to the distant universe well beyond what any astronomer could hope to see otherwise. The oldest style of telescope is the refractor, where light from an arbitrarily distant source is passed through a converging lens. The incoming light rays—initially spread over a large area—are brought together at a point on the opposite side of the lens, with light rays from significantly closer sources bent in characteristic ways as well. While the universe doesn't consist of large optical lenses, mass itself is capable of bending light in accord with Einstein's theory of General Relativity, and acts as a gravitational lens!

The first prediction that real-life galaxy clusters would behave as such lenses came from Fritz Zwicky in 1937. These foreground masses would lead to multiple images and distorted arcs of the same lensed background object, all of which would be magnified as well. It wasn't until 1979, however, that this process was confirmed with the observation of the Twin Quasar: QSO 0957+561. Gravitational lensing requires a serendipitous alignment of a massive foreground galaxy cluster with a background galaxy (or cluster) in the right location to be seen by an observer at our location, but the universe is kind enough to provide us with many such examples of this good fortune, including one accessible to astrophotographers with 11" scopes and larger: Abell 2218. Located in the Constellation of Draco at position (J2000): R.A. 16h 35m 54s, Dec. +66° 13' 00" (about 2° North of the star 18 Draconis), Abell 2218 is an extremely massive cluster of about 10,000 galaxies located 2 billion light years away, but it's also located quite close to the zenith for northern hemisphere observers, making it a great target for deep-sky astrophotography. Multiple images and sweeping arcs abound between magnitudes 17 and 20, and include galaxies at a variety of red shifts ranging from z=0.7 all the way up to z=2.5, with farther ones at even fainter magnitudes unveiled by Hubble. For those looking for an astronomical challenge this summer, take a shot at Abell 2218, a cluster responsible for perhaps the most glorious gravitational lens visible from Earth! Learn about current efforts to study gravitational lensing using NASA facilities: http://www.nasa.gov/press/2014/january/nasas-fermi-makes-first-gamma-ray-study-of-a-gravitational-lens/ Kids can learn about gravity at NASA’s Space Place: http://spaceplace.nasa.gov/what-is-gravity/

Abel 2218. Image credit: NASA, ESA, and Johan Richard (Caltech). Acknowledgement: Davide de Martin & James Long (ESA/Hubble).

AN ACCOUNT OF THE WADHURST ASTRONOMICAL SOCIETY INCLUDED IN THE WADHURST TIME-CAPSULE

Wadhurst Astronomical Society 2014

Here are some of our members in June 2014, a happy band of astronomically minded folk. Our Society has been running now since 1997 when it was formed by a group of adult students who were studying together at the Uplands Community College to gain a GCSE certificate in Astronomy. We now have 41 members that range in age from the middle teens to over 80 years old and come from as far afield as Hastings, Crawley and Bromley. Membership is £16 per year. John Vale-Taylor is our Chairman and heads a committee consisting of Vice Chair John Lutkin, Secretary & Programme Organiser Phil Berry, Treasurer Mike Wyles, Newsletter Editor Geoff Rathbone, Director of Observations Brian Mills FRAS, Catering Paul Treadaway plus Eric Gibson, Jim Cooper and John Wayte. We meet on the third Wednesday of every month excepting August when we have a Summer BBQ and star party instead of a meeting. Our regular meetings comprise of a talk from a member or invited guest speaker on a topic of astronomical interest. This normally lasts an hour and then we have a free tea or coffee break followed by a short talk on basic astronomy and the month's Sky Notes where Brian Mills FRAS, our Director of Observations, tells us about items of interest in the night sky for that month. The talks so far this year have been on "Totality", an account at our January meeting by our secretary, Phil Berry, on his month long cruise to see a hybrid eclipse off the coast of Africa on 3rd November 2013. Like many eclipses it was plagued with bad weather and other than getting dark there was no sighting of the actual eclipse. In February another member, Dr. Jan Drozd, gave us the benefit of his considerable knowledge on "The Earth, Life and the Universe". In March we invited the former BBC Science Correspondent Dr. David Whitehouse who talked to us about "The Next 50 Years Of Space Travel". At this time of course you will know that the only manned missions have been to the Moon and the last one, Apollo 17 was 43 years ago in 1971. The United States of America is now contemplating manned missions to an asteroid and also Mars but our speaker said we should be practising on the Moon again as this could become a very useful staging post, not too far away, to test out the methods and learn the lessons that will be essential on Mars. Another recent speaker was Stephen Tonkin FRAS who is a well known specialist in binocular astronomy and writes each month in a national publication called "The Sky at Night" magazine. It is based on the BBC Sky at Night television programme so I hope it is still going in 2114! Stephen's talk was called "10 Ways the Universe Tries to Kill You!", so hopefully you are still going too! Stephen warned us of the dangers of Gamma Ray Bursts, Magnetars and Cosmic Rays to name just three. On the 18th June 2014 we held an "Open Evening" where we invited members of the public to come and see some telescopes and receive help, advice and tips on how to start astronomical observing. A picture of us all at this meeting is included above. We are very fortunate as the night sky in the Parish of Wadhurst is not only very dark but is actually amongst the darkest in the country. In order to protect this quality of sky for future generations, our Secretary, Phil Berry, surveyed the whole parish with the idea of presenting a document to the Parish Council that would suggest ways to preserve the night-time darkness and, where needed, improve on any poor quality street lighting. Following the presentation of his report entitled "Preserving the Dark Sky of Wadhurst" the Parish council agreed, in 2013, to adopt a dark sky policy. The measurements taken at the time of the survey had an average of 20.08 Mags/arcsec with the best being at the Snape Wood car park at 21.09 Mags/arcsec. These readings are comparable with areas designated as National Dark Sky Reserves, so we sincerely hope that in 2114 the policy has continued and you are enjoying seeing the number of stars and the Milky Way that we do in 2014. Each month Geoff Rathbone our newsletter editor publishes an excellent and popular newsletter for our members whilst Brian Mills FRAS publishes in the Wadhurst "Focus" parish magazine a report on a topic of astronomy and some sky notes of interesting astronomical events for the month. Brian Mills has used his software to predict the night sky for you on the 29th June 2114, the day that you open this time capsule. We hope you are able to enjoy seeing some of the events predicted. The Night Sky in Wadhurst - June 29th 2114 by Brian Mills FRAS As the Sun sets at around 9.20pm (BST), the planet Venus can be seen at a height of 20° and lying due west. If you look at it with binoculars you will see that it isn’t round but has a phase similar to that of the Moon when just past first quarter. In the north-west Ursa Major, the Great Bear, which contains the group of stars known as “The Plough”, is pointing towards the horizon. Its smaller cousin, Ursa Minor, the Little Bear, is standing on its tail. If you draw a line through the two stars at the front of the bucket of the plough and extend them to your right you will come to the pole star, Polaris, which is at the end of the little bear’s tail.

Looking eastwards at 10pm the three bright stars of the “Summer Triangle” will be visible, with the brightest of them, Vega in the constellation of Lyra, due east at an altitude of 55°. The other members, Deneb in Cygnus and Altair in Aquila, lie to either side and little lower. If you look towards the south, you will see two bright objects quite low down. The brightest of them is the planet Jupiter, whilst the other is the star Antares in the constellation of Scorpio. The name means “rival of Mars” and is very appropriate due to the star’s ruddy hue. Jupiter increases in altitude as the evening progresses and by midnight it is due south at an altitude of just over 15°. If you have binoculars look at the planet and see if you can spot any of the four Galilean moons. During the evening two of them, Io and Europa, will transit across the face of their parent planet. The other two can be seen with Callisto to the east (left) and Ganymede to the west.

************************* In the lifetimes of many of our members we have seen staggering advances in science and astronomy including the first manned voyages to our Moon. Things that are yet to be understood in 2014 are dark matter, dark energy and extraterrestrial life as well as the extent of the universe or universes! We can only wonder at what marvels you can now see and enjoy. We hope you find astronomy every bit as exciting as we all do. Clear skies and the very best for the future from us all here at the Wadhurst Astronomical Society in 2014.

CONTACTS

General email address to contact the Committee wadhurstastro@gmail.com Chairman John Vale-Taylor Secretary & Events Phil Berry 01892 783544 Treasurer Mike Wyles Editor Geoff Rathbone 01959 524727 Director of Observations Brian Mills 01732 832691 Committee Members Paul Treadaway Jim Cooper John Lutkin Eric Gibson John Wayte Wadhurst Astronomical Society website: www.wadhurstastro.co.uk SAGAS web-sitewww.sagasonline.org.uk Any material for inclusion in the August 2014 Newsletter should be with the Editor by July 28th 2014