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BUILDING WORK AT UPLANDS COMMUNITY COLLEGE When we return to Uplands Community College for the September 18th meeting we expect to see some major changes due to building work, which was planned to begin immediately after the start of the summer break. Large portions of the college are due to be demolished and replaced with buildings more suitable and fit for purpose than the old original ones with a number of temporary buildings being used in the interim. The college have assured us that the work will have no effect on our meetings because the block that contains classrooms IL5 and IL6 is newer and will remain in use. It is likely that some parking space will be used for the temporary classrooms so you may have to park somewhere other than the old tennis courts. However, that should be the extent of the effects on the Astronomical Society.

THE NEXT OBSERVING EVENING We are planning another observing evening on 19th or 20th of September at Friends Clump on Ashdown Forest. Friends Clump is on the road between Duddleswell and Nutley. This is called Crowborough Road and if driving from the Duddleswell end it is approximately 1.5 km from the junction with the B2026. The car park is on the right hand side, a little after the “Box Car Park” which is also on the right. The starting time will be 2000 and parking is available nearby. We will have some telescopes set up and of course members may want to bring their own. Jupiter and Saturn will be visible and also Globular cluster M13, the best in the Northern sky, may be visible and of course M31 in Andromeda will be observable. The Summer Triangle will be visible with Cygnus and Lyra containing some interesting objects. This is an opportunity to view the gas giants and to get some help with spotting them together with some of the more difficult objects. There has been some interest shown by the U3A astronomy group who joined us at our last observing evening. Ian McCartney – Director of Observations

MEETINGS There was no meeting of the Society in August.

SEPTEMBER MEETING 18 September 2019 – At this month’s meeting and in October, Graeme Awcock is giving a series of talks about the Cassini Mission to Saturn. This month he begins with “Remote Sensing of the Saturnian System; The Titanic Struggle to Get There” Meetings will take place at Uplands College, Lower High Street, Wadhurst and are held in classrooms IL5 and IL6, which are in the blue walled classroom block at the far end of the drive from the main gate and up by the tennis courts, although these could be occupied by some new temporary classrooms. Signs will direct you. There is car parking near the block although this needs to be cleared before 2230 when the main security gates close. The Post Code is TN5 6AZ, Meetings begin at 1930 prompt although members are invited to arrive anytime after 1900, as this is a good time to exchange ideas and discuss problems and also help set things up before the meeting starts. Anyone is welcome but visitors are asked for a small fee of £3.

FUTURE MEETINGS 16th October 2019 – Graeme Awcock concludes his talks about the Cassini Mission with “Remote Sensing of the Saturnian System; A Tale of Two Moons; Atmospheres and Oceans”.

Wadhurst Astronomical Society Newsletter

September 2019

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20th November 2019 – Jan Drozd compares the history and geology of the Earth, Moon and Venus in his talk entitled “Earth and its Neighbours”. 11 December 2019 (Second Wednesday of the month) – Brian Mills FRAS tells us more about “The Work of Female Astronomers” 15 January 2020 – There will be a brief Annual General Meeting followed by a talk. TBC

RETURN TO JUPITER’S MOON, EUROPA For some time now the European Space Agency (ESA) has been preparing for a return to Jupiter’s moons in a mission called JUICE (JUpiter ICy moons Explorer) with a planned launch date of May 2022 and arrival at Jupiter in October 2029. On August the 19th this year NASA announced that its mission, Europa Clipper has cleared a major review and has confirmed that the mission is to proceed to its next stage saying that it could be ready to launch as early as 2023. This prompted me to look further into the reasons for returning, particularly to Europa. The material used in this article has been obtained from both the ESA and NASA websites.

Jupiter’s moon, Europa is the smallest of the four Galilean moons and its orbit is the sixth nearest to Jupiter of all the 79 known moons. It is slightly smaller than our Moon but despite this Galileo Galilei first discovered it as long ago as 1610 using his 20-times refracting telescope. Then in 1973 and 1974, Pioneer 10 and 11 respectively, took low-resolution pictures of the moon during Jupiter flybys.

Europa with its icy surface and cracks through which material has seeped NASA/JPL

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In 1979 the two Voyager probes provided more detailed images of Europa’s icy surface and this led to a lot of speculation about there possibly being a giant liquid ocean beneath the surface. More images were taken by the Galileo space probe between 1995 and 2003 and further ones taken during the flyby of New Horizons on its way to distant Pluto, each with increasing amounts of detail. The Hubble Space Telescope has also photographed plumes of water vapour rising from the moons surface.

It is now known that the surface is mainly composed of ice possibly covering an ocean of slushy ice. It is also believed that Europa has twice as much water as the Earth does. Astro-biologists think there is potential for habitable-zone life forms analogous to some found in extreme conditions on Earth.

Image of Europa taken by Pioneer 10 in 1973 NASA/JPL

A more detailed image of Europa taken by Voyager 2 in 1979

NASA/JPL

Image taken by the Hubble Space Telescope in January 2014 showing water vapour venting from Europa’s surface bottom left.

NASA/JPL

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At present the Juno Mission, launched in 2011 is orbiting the planet Jupiter and increasing interest is being shown in Europa as more is learnt both by NASA and the European Space Agency ESA, leaving much to be investigated or confirmed. Europa has a nearly circular orbit and is tidally locked to Jupiter, which means the same side faces the planet all the time. Because of the slight change in the distance from Jupiter during its orbit, major stresses occur to Europa’s icy surface which is thought to be about a 10 to 15 miles thick shell, resulting in cracks through which it is thought slightly salty water-ice and sulphur compounds ooze. Beneath the surface-ice, there is believed to be a liquid ocean between 40 and 100 miles deep, the water being kept in a liquid state by heat generated by the continual flexing of the moon. Astro-biologists think this flexing could also cause volcanism or hydrothermal vents in the ocean floor, supplying nutrients that could be suitable for life. Europa is believed to have an iron core and rocky mantle but this remains to be confirmed. There is a slight magnetic field but scientists think this may be being caused by Jupiter’s own magnetic field inducing currents in the salty water. There is a very tenuous oxygen atmosphere, not produced biologically but being maintained by charged particles that hit the cold surface and produce water vapour. The surface temperature never rises above -160oC and the poles are about -220oC. Europa is around 4.5 billion years old having formed at the same time as Jupiter, it has a diameter of 1,900 miles, orbits at about 414,000 miles above Jupiter, taking about 3½ Earth days to make one orbit and the reflectivity of the surface is quite high at 0.64. Our Moon’s reflectivity is only around 0.12. ESA’s JUICE mission is due to last for 3 years and will make detailed observations of Jupiter, Ganymede, Calisto and Europa. It will be looking for what conditions exist for planet formation and the emergence of life. It will attempt to determine how the Solar System works and also look at the emergence of habitable worlds around gas giants. During the observation of Europa, the focus is on the chemistry essential for life including organic molecules. There will be an attempt to understand better the formation of surface features and the composition of the non water-ice material. It is also intended to determine the minimal thickness of the icy crust over the most recently active regions. NASA’s Europa Clipper will use looping orbits around Jupiter to bring it close to Europa during flybys. It is intended to determine the thickness of the surface with ice-penetrating radar and to search for sub-surface lakes. Magnetometer measurements will be made to find the strength and direction of the moon’s magnetic field, which will allow scientists to determine depth and salinity of its ocean. Gravity measurements will help confirm the existence of Europa’s subsurface ocean. The mission will also look for recent eruptions. NASA’s Europa Clipper will compliment ESA’s JUICE and although due to launch at a later date, will take a more direct trajectory and the two missions should arrive at more similar times. Geoff Rathbone

THE APOLLO STORY – Part 3 In pursuit of President Kennedy’s promise, Apollo 8 blasted off on December 21st 1968 atop a Saturn 5 rocket and after a brief spell in Earth orbit the engines fired to break out and head towards the Moon. During the ten lunar orbits that followed the crew were able to practice some details for future missions as well as photograph both the near and far sides of the Moon. They also made a number of broadcasts one of which was when they famously read from the Book of Genesis on Christmas Eve. Apollo 8 did not carry a Lunar Module (LM) although it was ballasted to synthesise for the presence of one. The mission was deemed a success allowing the next flight to go ahead with both a crew and an LM on board for the very first time. Apollo 9 launched on March 3rd 1969 but remained in Earth orbit to test the functionality of the LM as a separate entity capable of sustaining life in its own right. Manoeuvrability of the module was tested to simulate docking in lunar orbit and two of the astronauts, David Scott and “Rusty” Schweickart, performed space walks. This was another successful mission whose completion gave the green light for a full lunar flight which would do everything planned for Apollo 11 apart from touch down on the surface of the Moon. Apollo 10 was very much seen as a full dress rehearsal or a “dry run” for the lunar landing mission to follow. It launched on May 18th 1969 and following just one and a half orbits of Earth it left to become the second Apollo to go to the Moon. It carried a full compliment of modules for the first time and included the Command and Service Module (CSM) nicknamed “Charlie Brown” and the LM, “Snoopy”. Also aboard were three astronauts Thomas Stafford, John Young and Eugene Cernan who would all go on to crew later Apollo missions. During the three day journey to the Moon Young separated the CSM from the LM adaptor, turned it around and docked onto the LM to withdraw it. On arrival they entered lunar orbit and leaving Young in the CM Stafford and Cernan crawled through into Snoopy. The two craft separated and tests were carried out on both the engines for the descent stage

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(which was jettisoned and crashed into the Moon) as well as the ascent stage of Snoopy. NASA had concerns that the crew would attempt a landing so short-fuelled the ascent stage to prevent this happening. In the book “Rocket Men” Eugene Cernan said in an interview “.....had we literally tried to land on the Moon, we couldn’t have gotton off.” Following tests on the radar systems the two craft docked again before the ascent stage of the LM was released and sent off into orbit around the Sun. Following an uneventful return flight splashdown occurred in the Pacific Ocean on May 26th 1969. To be continued........ Brian Mills FRAS

SKY NOTES FOR SEPTEMBER Planets Mercury reaches superior conjunction (when it is on the far side of the Sun) on September 4th after which it moves to the east of our star to become an evening object. However, its negative declination is quite large so that even by the end of the month, with an elongation of 18°, it sets less than thirty minutes after the Sun. Things don’t improve as greatest elongation approaches (on October 20th) when the planets angular distance from the Sun is a very respectable 25° but it still disappears thirty minutes after sunset making observation all but impossible. Venus was at superior conjunction in mid August and is also now moving into the evening skies. The appearance of the brightest of planets will not be a speedy one but it will be well worth waiting for when it eventually arrives. By the end of September, Venus will be 13° from the Sun but will set just 30 minutes after it. This equates to it being 4° above the west-south-western horizon as soon as the Sun has disappeared. Given that its magnitude is -3.9 it will make locating it easier although if you choose to sweep for it with binoculars do make sure that the Sun is indeed below the horizon before doing so. As I hinted above, this will eventually be an excellent apparition for Venus although it will be March 2020 before it next reaches greatest eastern elongation at 46° from the Sun which translates to it being 41° high in the west at sunset. When darkness falls it will shine like a beacon to rightfully justify its title “The Evening Star”. Earth reaches the autumnal equinox on September 23rd at 08:51 BST. This is when the centre of the Sun reaches the intersection of the ecliptic and celestial equator. Because it is moving south from the northern to the southern hemisphere we describe it as the “descending node”. At the spring equinox the Sun is moving north and so is at the “ascending node”. Day and night are of roughly equal length and the Sun can be seen to rise due east and set due west. Mars is at solar conjunction on September 2nd and so will be too close to the Sun for observation this month. It will eventually appear to the west of the Sun as a morning object though it will be late October or early November before it becomes easier to locate. It will brighten gradually as it approaches opposition in October 2020. Jupiter is now well past opposition but still comparatively well presented given that due to its negative declination it has been low in the sky for the whole of the current apparition. It shines as a brilliant object in the south west at magnitude -2.1 and is still within the confines of the southern part of Ophiuchus although it is now moving direct (eastwards) though it will be mid November before it crosses the border into neighbouring Sagittarius. Fig 1 shows its position in the middle of the month at 20:15 at which time Jupiter will be 12° above the south-south-western horizon. On that date the planet will appear as a disk with a very reasonable equatorial diameter of 37.5 arc seconds (it was 46 arc seconds at opposition) which will gradually decrease throughout the rest of 2019. The Great Red Spot (GRS) is visible in very modest telescopes so I have included some of the best dates and times to see it when it is on the central meridian of Jupiter’s disk. An approximately first quarter Moon is close by on September 5th and 6th. Don’t forget to look for the four Galilean moons as they continuously change their positions as they orbit their parent planet. Jupiter is now moving into the twilight and sets less than three hours after the Sun by the end of the month.

Sept. GRS Transit Sept. GRS Transit Sept. GRS Transit 3rd 21:30 15th 21:28 25th 19:47 8th 20:40 20th 20:38

Saturn is also shown in fig 1 as it occupies a similar area of sky to Jupiter. In fact next year, a few days before Christmas, the two planets will pass within just 6 arc minutes of each other. This is something we will be able to observe, low down, in the south west after sunset. However, currently Saturn is similar to Jupiter in as much as it is well past opposition and low in the sky. If you observe either of the gas giants then patience is needed to get the best views. Because they are so low, we see them through a much thicker layer of the Earth’s atmosphere which in turn causes the image to appear to be constantly unsteady. However, if you are patient and watch for a while you will experience short spells when the planet “snaps” into focus and all the features become really distinct. This was really obvious when I observed Saturn on the night of August 24th when, for short periods, there was perfect focus and the Cassini division and surface markings were momentarily pin sharp. However, lack of altitude shouldn’t be a reason not to observe the ringed planet because the tilt of its north pole is still inclined to the Earth by more than 25° giving us superb views of the upper surface of the ring system. The planet’s brightness, which is now +0.4, is falling very slowly as is its apparent size, now 38.5 arc seconds including the rings. It still resides amongst the stars of Sagittarius and reaches its second stationary point on September 18th after which it resumes direct (easterly) motion once more. Titan is Saturn’s largest natural satellite and in fact the second largest in the entire solar system. Only Ganymede, one of Jupiter’s moons, is larger and in fact both are bigger than the planet Mercury. Titan was the first of Saturn’s moons to be identified, though another 61 have since been added, almost certainly because it is the brightest at magnitude +8.2. This makes it easily identifiable in amateur telescopes although it is best to look for it when it is at elongation, or furthest from its parent planet. During September western elongation occurs on the 12th/13th and 28th/29th and eastern elongation on 4th/5th and 20th/21st. Saturn is close to the waxing gibbous Moon on the 8th and is, in fact, occulted by it as seen from parts of the southern hemisphere.

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Uranus, often referred to as an “Ice Giant”, is currently within the boundaries of Aries where it remains until mid June 2024. It shines at magnitude +5.7 so can easily be found in a small amateur telescope or binoculars. However, irrespective of the instrument that you use, you will be unable to see any surface markings or, more correctly, markings in the clouds that surround the planet. Even images taken with large telescopes, or indeed those returned from Voyager in the late 1980’s, gave any hint of storms or cloud formations in the ammonia and methane rich atmosphere. It is the only planet in the solar system that is named after a Greek god rather than a Roman one as is the case with all the others. The position of Uranus is shown in fig 2. It rises at 21:30 at the beginning of the month but by the end this has become 19:30. Neptune is fainter at magnitude +7.8 so binoculars will show it although a considerably larger instrument will be needed to show it as a tiny blue disk that is just 2.4 arc seconds across. It is also further south than Uranus amongst the stars of Aquarius. If you have never seen Neptune then early September is an ideal time to look for it because on the 7th it passes extremely close to the magnitude +4.2 star φ (phi) Aquarii. On that night the distance between the two bodies is a tiny 42 arc seconds. The star will actually pass between the planet and its moon Nereid. Neptune rises at 20:00 at the start of September but by the last day it rises in daylight and culminates at 23:30. Its general position is shown in fig 2 but fig 3 is zoomed in and shows psi Aquarii as a means of providing context between the two diagrams.

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Lunar Occultations In the table below I’ve listed events for stars down to magnitude 8.0 that mostly 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, RD = reappearance at the dark limb and RB = reappearance at the bright limb. The column headed “mm” (millimetres) shows the minimum aperture telescope required for each event. Times are in BST.

Sept. Time Star Mag Phase % illumination mm 2nd 20:36 ZC1976 7.0 DD 16 70

14th 20:11 ZC3536 4.4 RD 99 80 Phases of the Moon for September

First ¼ Full Last ¼ New 6th 14th 22nd 28th

ISS Below are details for the evening passes of the International Space Station (ISS) this month. The details of other passes, including those visible between midnight and dawn, can be found at www.heavens-above.com. Please remember that the times and directions shown below are for when the ISS is at it’s maximum elevation, so you should go out and look at least five minutes beforehand. Times are in BST.

Sept. Time Mag. Alt° Az. Sept. Time Mag. Alt° Az. 20th 20:19:46 -2.2 19° SE 26th 20:14:39 -3.9 90° NNE 21st 21:06:02 -2.8 36° SSW 27th 19:25:29 -3.8 76° SSE 22nd 20:17:58 -3.1 36° SSE 27th 21:01:47 -3.4 64° WNW 23rd 19:29:00 -2.5 25° SSE 28th 20:13:01 -3.8 78° N 23rd 21:05:00 -3.6 65° SW 29th 19:23:49 -3.8 82° N 24th 20:16:17 -3.8 63° SSE 29th 20:59:56 -3.2 56° W 25th 19:27:12 -3.3 46° SSE 30th 20:11:22 -3.9 85° NNE 25th 21:03:31 -3.6 71° WNW

Iridium Flares Below are the only two evening predictions for bright Iridium flares this month. These predictions are location specific so if you wish to see a complete list, or obtain timings for somewhere other than Wadhurst go to www.heavens-above.com . 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 then. Times are in BST.

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Sept. Time Mag. Alt° Az. Sept. Time Mag. Alt° Az. 18th 21:53 -5.8 10° 359° (N) 26th 20:30 -6.6 30° 4° (N)

The Night Sky in September (Written for 22.00hrs BST mid month) In the east Pegasus and Andromeda are well clear of the horizon with M31 almost 50° in altitude though closer to the horizon the appearance of the Pleiades is an indicator that autumn is upon us. The double cluster in the sword handle of Perseus and the Heart and Soul Nebulae in neighbouring Cassiopeia are also at a similar altitude. Some 15° below M31 lies M33 the Triangulum Galaxy which, rather appropriately, lies within the boundaries of the celestial triangle and in common with M31 it is one of the most distant objects that can be viewed with the naked eye. At magnitude +5.7 it was one of the objects observed by Lord Rosse using the 72 inch “Leviathan of Parsonstown” when he saw the spiral nature of such galaxies for the first time. Above Andromeda is the small group of stars that form Lacerta, the lizard. It ranks 58th in order of size and contains few bright deep sky objects although there are a number of open clusters with NGC 7243 and NGC 7209 being the most obvious at magnitudes +6.4 and +6.7 respectively. Looking towards the south the most easterly of the three members of the Summer Triangle, Deneb, has reached the meridian. Directly south of Deneb are the small constellations of Delphinus, the dolphin and Equuleus, the small horse both of which belong to the original list of 48 devised by Ptolemy in the second century AD. Whilst, with a little imagination, it might be possible to envisage the stars of Delphinus resembling a leaping dolphin it is in no way possible to see the four brightest stars of Equuleus conjuring up an image of a foal. A little further south but still on the meridian brings us to Aquarius which contains the second object on Charles Messier’s list, M2 a fine globular cluster with a magnitude of +6.3. If you have an excellent southerly aspect then take a look for the northern section of Microscopium that is just approaching the meridian and visible from the southern parts of the UK around this time. Just east of the stellar microscope is the first magnitude star Fomalhaut, in Piscis Austrinus, that is easily located by drawing an imaginary line through the two most westerly stars in the Square of Pegasus and continuing it towards the horizon. In the west the last vestiges of Virgo are disappearing soon to be followed by Ophiuchus which houses a large number of globular clusters, the brightest of which are M10 and M12 located centrally in the serpent bearer and both with magnitudes of +6.6. Serpens Caput, the serpent’s head, will be lost from view first taking with it M5, another globular, that some estimate contains half a million stars. Arcturus is also approaching the horizon and at a similar altitude is another globular, M3 at magnitude 6.4, which lies just across the border in Canes Venatici. To the north, the “nose” of Ursa Major is just on the meridian immediately below the pole with the popular pair of galaxies, M81 and M82 still moderately well placed from the southern UK. The main body of Auriga is now clear of the horizon along with the brilliant Capella that will ride high in the sky in the depths of winter. Above the pole are the majority of Draco and Cepheus the latter of which contains a variety of open clusters, the brightest being NGC 7160 at magnitude 6.1. It also accommodates the well known Elephant’s Trunk Nebula within its boundaries. Brian Mills FRAS

CONTACTS General email address to contact the Committee wadhurstastro@gmail.com Chairman - Brian Mills FRAS 01732 832691 Secretary - Phil Berry 01580 291312 Treasurer - John Lutkin Membership Secretary - John Wayte Newsletter Editor - Geoff Rathbone 01959 524727 Observing Director - Ian McCartney Librarian - Phil Berry Catering Manager - Jim Cooper SAGAS Representative - Eric Gibson Wadhurst Astronomical Society website: www.wadhurstastro.co.uk SAGAS website: www.sagasonline.org.uk Any material for inclusion in the October 2019 Newsletter should be with the Editor by September 28th 2019