MEETINGS

APRIL MEETING

The April meeting began with Phil Berry giving details of the arrangements for the visit to Herstmonceux Science Centre. These details for those going can be found under “Further Information” later in this newsletter. He also reminded members that subscriptions for the current session of the Society were due on the first of January and the new membership list will be drawn up at the end of May.

Phil then introduced David Styles who gave the April talk. Dave is a member of the fast growing and enthusiastic Ashford Astronomical Society and he described himself as a keen beginner as an amateur astronomer.

The Ice Giants

Dave Styles

Defining a planet has become quite a field of intrigue but Dave took us through the definitions as agreed by the International Astronomical Union in 2006, which shows that the main difference between a true and a dwarf planet is that a dwarf planet has not cleared the area around its orbit and also isn’t itself a satellite. All planets orbit the Sun in nearly circular orbits.

James Blish, a science fiction writer who wrote some of the Star Trek novels is the first person to have referred to the Ice Giants and now we were taken through the story of the discovery and naming of the Seventh Planet.

Planet Uranus

Image: NASA

The first sightings were made by Flamstead in the late 1600s although at the time he thought it was a star. Later it was seen a number of times by a French astronomer, then William Herschel thought it was a comet and it was Maskelyne who finally recognised it for what it was.

German and Russian astronomers refined the seventh planet’s orbit further and afterwards, Maskelyne credited Herschel as the discoverer and asked him to name it. Herschel called it George’s Star, but Dave said the French were not impressed and called it Herschel. The Germans called it Uranus, from Greek mythology and this caught on and remains today.

A discussion on its pronunciation took place and Dave finally left it up to us…

As early as the 1600s, Galileo recorded sightings of the eighth planet but he thought it was a fixed star.

In 1812, Bouvard calculated tables of its position but they were soon found to be incorrect.

Later Adams calculated the position of the planet and sent his calculations to Airy the Astronomer Royal, but no-one did anything about it.

About the same time a French astronomer, Le Verrier, did the same calculations and again no-one did anything about it until, as Dave pointed out, the British got the wind up that the French were on to something and Airy asked someone at Cambridge observatory to look in the suggested direction, but they found nothing.

The Frenchman, Le Verrier got someone to look in the right direction and they did find something.

As Dave explained, the French and British astronomers were spurred on to determine the exact position of this eighth planet before the other; the French had an error of 1% - the British, an error of 12%!

The French named it Janus and the British named it Oceanus. Le Verrier nearly called it Neptune but named it Le Verrier. The Russians suggested everyone went with Neptune and so it is today.

Now we looked at the data and compared the two Gas Giants. The meeting was told that surprisingly, only Voyager-2 had visited Uranus back in 1986 and Neptune in 1989 although Hubble has subsequently obtained a notable amount of information from a great distance.

Uranus has a diameter about 4 times that of Earth and is about 3 billion kilometres from the Sun; much more data can be found on the Internet.

The surface is covered in a layer of methane, beneath which there is a thick layer of liquid hydrogen which surrounds a huge layer of ice, but the core is thought to be molten rock.

An amazing fact revealed by Dave is that Uranus has an inclination to the Solar plain of 97 degrees and rolls around the ecliptic. He considered the reason for this and said there was a theory that Uranus had been in some kind of collision early in its existence.

Uranus does have faint rings but with no spectral features and consists of very dark material. From Dave’s picture of the rings, they would be vertical seen from Earth and only be edge on very rarely.

We were told that there needed to be some kind of mechanism to hold the rings in place such as nearby moons otherwise they would just spread out and be lost in about a million years or so.

At present, 27 Uranian moons are known, all named after characters in Shakespeare’s and Alexander Pope’s writings.

Finally Dave took us through what we know about Neptune who is marginally smaller than Uranus and is very similar in its make-up. It is over 4 billion kilometres from the Sun.

There was a large dark spot on the surface of Neptune, recorded in 1989 but it had since disappeared after only a few years.

The winds on Neptune have the highest wind speeds in the whole of the Solar System.

Neptune

image: NASA

Again there is a faint ring system although Dave did say they had deteriorated since being seen by Voyager-2 in 1989. At present 13 moons are known; one really huge one is Triton

There were discrepancies in Neptune’s orbit but we told that voyager-2 had found an error in the planet’s estimated mass and it was in the right place after all, and there was no “X” planet! (as had been suggested earlier)

It is now thought that Neptune must have passed through the Kuiper belt at some stage and Dave explained how material had been thrown towards Uranus which could account for Uranus’s tilt. More material was also thrown towards Saturn and Jupiter.

No plans have been made for a mission to Uranus, but there were plans to go to Neptune in about 2030-ish with a lander to Triton and probes to look at Neptune’s atmosphere. This mission would take twenty years to get there but at present these plans have been put on hold.

The talk was delivered with a great deal of humour but with its serious side too.

MAY MEETING

Wednesday 19^th May 2010 – Simon Allen gives a talk about “Space Elevators”. Simon is the Secretary of the East Sussex Astronomical Society who meet in Bexhill-on-sea once a month.

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 relax before the talk.

The venue as always is in the Upper Room of the Methodist Church at the east end of Wadhurst Lower High Street, opposite the entrance to Uplands College. (For those with SatNav – the post code is TN5 6AT)

FUTURE MEETINGS

Wednesday 16^th June 2010 – This is the Society’s annual Open Evening when there will be some short talks and software demonstrations, together with photographs thought to be of interest. A number of telescopes and other astronomy aids will also be present to look at and hopefully there will be enough expertise to answer questions.

It is hoped to attract members of the public who have an interest in astronomy and may even recruit new members.

Society members are invited to bring anything along they think may interest others.

It will be an informal evening and of course biscuits and coffee will be on hand.

Wednesday 21^st July 1020 – Steve Jackson from Ashford Astronomical Society will be visiting us and giving a talk on “An Introduction to Radio Astronomy”.

OTHER NEWS AND INFORMATION

ARRANGEMENTS FOR THE HERSTMONCEUX VISIT

Phil Berry has a list of members who showed interest in joining the visit to Herstmonceux on Saturday the 15^th of May but other members can turn up on the day, although Phil would prefer to have an idea of numbers beforehand if possible.

Cars can be parked in the Observatory Science Centre and I have copied the directions given by the Science Centre web site shown below:

If you use Google maps with The Centre's postcode, you will be directed to the closed entrance of the estate.

Likewise, GPS users please DO NOT use this postcode in your GPS as this will take you to the closed entrance of the Herstmonceux Castle Estate and will result in a 15 minute re-route. The correct front entrance is at the junction of Wartling Road and Halley Road (Private).

The Observatory Science Centre is within the Herstmonceux Castle Estate in East Sussex. It is 2 miles east of the village of Herstmonceux on the Boreham Street to Pevensey Road, near Wartling. Look for the brown signs to 'Herstmonceux Castle and Science Centre'.

Unfortunately there is a shortage of these brown directional tourist signs and the Highways Agency does not permit us to add any more. As you near The Centre, if you can spot the green, copper clad domes – or the grey, steel Isaac Newton Dome, then you are almost there!

From the north The most direct route is to continue south on the A22 to the large Cophall Roundabout at Polegate, just north of Eastbourne, then proceed as below (from the west).

From the west travel along the A27 to Polegate, then at the Cophall Roundabout follow the A22 / A27 eastbound to Pevensey. At the Pevensey Roundabout, take the 1st exit on the left and follow the sign for Herstmonceux Castle, 3 miles along the Wartling Road.

From the east travel along the A259 to the Pevensey Roundabout. Take the 4th exit and follow the sign for Herstmonceux Castle, 3 miles along the Wartling Road.

We will meet in front of the Science Centre ready to enter at 1100.

The cost per adult is £7.40, seniors; £5.80 and children between 4 and 16; £5.55 although if we number 15 or more the cost is reduced.

At 1300 we will be taken on a guided tour of the facility, seeing some domes and equipment not normally open to the public. This tour will take about an hour.

RECOGNITION OF INVALUABLE SERVICE TO THE SOCIETY

For quite a number of years Phil Berry has been involved in helping to run the Society and following the death of Ian Reeves also took on the role of organising the meetings and finding speakers.

He has also arranged many Society outings such as our trip to Belmont House and two trips to Greenwich Observatory. This year amongst other outings he is organising our forthcoming visit to Herstmonceux.

He has given talks about various subjects such as the Strasbourg clock and the story of building his observing dome.

In addition to this Phil and his wife, Nicky hosted both the Spring and Autumn Moon Watches.

Phil has also represented us a number of times at SAGAS, the Southern Area Group of Astronomical Societies and with all this in mind, members suggested some kind of recognition and the Committee were asked if it would be possible to give Phil Life Membership of the Society. So at the April meeting the Chairman, John Vale-Taylor presented him with a framed certificate beautifully crafted by our Director of Observations, Brian Mills.

SUBSCRIPTIONS 2010

The current session of the Society is well under way. The subscriptions remain the same as in recent years. Membership for the year is still £15.00 and £20 for two members within the same family. Children and students are free and are always welcome.

The member’s list for the current session will be drawn up at the end of May.

Subscriptions can be still be made at the meetings, preferably by cheque payable to “Wadhurst Astronomical Society” or can be posted to our Treasurer, Michael Wyles at:

31 Rowan Tree Road

Tunbridge Wells, Kent TN2 5PZ

SETTING UP A REFRACTING FINDER FROM SCRATCH

Aligning a Finder Scope with the main telescope is an important part of making it easier to locate objects in the night sky. Taking care with the set-up will greatly enhance the pleasure of using your telescope to search for objects either out of curiosity or from a star catalogue.

Having securely attached the Finder to the telescope so that there can be no movement of the finder’s mount, the screws holding the actual finder scope in place should be loosened slightly after focussing on a nearby object. The scope is usually held in place with three adjusting screws at 120^o to each other. It should be possible to loosen and tightened these with the fingers. Some come with screw-driver head slots only and these are near impossible to tighten firmly after adjustment.

The first part of the alignment should take place in daylight. Set the main telescope looking at something easily recognisable at some distance away, such as part of a distinguishable television aerial or church steeple but remember that this will be upside down in the main telescope and finder. Having centred this using a low magnification eyepiece, lock-off the telescope’s mount and point the finder more or less in line with the main telescope.

Now look through the eyepiece of the finder and using only two of the three adjusting screws, bring the object into alignment with the cross hairs. Both hands will need to be free to do this. I find it easiest to have both eyes open, bringing the real and finder images into line, despite the difference in size. Now tighten the adjusting screws enough to hold the scope in place for the time being.

Having achieved some sort of alignment, it is time to look at something much further away, reducing the effect of parallax a bit more. If possible, something on the horizon is useful to repeat the above alignment but be aware of heat haze.

Once night has fallen, a much more accurate alignment can take place using a star as far from the celestial equator as possible, this being Polaris, the Pole Star, found by following a line, up from the right hand two stars of the Plough. Finally using a higher magnification eyepiece in the main telescope, repeat this part of the alignment. Now the adjustment screws need to be tightened as much as possible; this can be difficult whilst still keeping everything in alignment but is well worth while.

At this stage, it helps if the graticule or cross-hairs in the finder scope can be illuminated.

One last check is to make sure the finder stays in alignment when looking at different parts of the night sky; there is nothing more annoying than discovering that having achieved perfect alignment between the finder and the main scope, the object being observed is not in the centre of the graticule due to something either in the finder scope or main telescope being loose.

Sadly, whenever the telescope is moved to a new location, this alignment will need to be checked and possibly repeated because it is very difficult to avoid knocking the finder out of alignment when moving any distance.

Geoff Rathbone

SKY NOTES FOR MAY

Planets

Mercury passed through inferior conjunction on April 28^th when it was between the Earth and the Moon. It continues towards greatest western elongation (meaning it becomes a morning object) which occurs on May 26^th though it will never be far enough above the horizon at sunrise to be observable from the UK.

Venus at magnitude -3.8, on the Taurus/Gemini border, is a brilliant evening object in the west after sunset and by mid month it sets almost three hours after the Sun.

Mars is currently in Cancer at magnitude +0.9 and moving steadily eastwards as shown in the map. It is decreasing in brightness and apparent size all the time.

Jupiter at magnitude -2.2 is brightening in the morning sky (in the south east) rising around ninety minutes before the Sun.

Saturn is well placed for observation in the constellation of Virgo at magnitude +0.9. Sadly the rings are never far from edge on causing the planet to be less bright that previously. Its retrograde motion halts on the last day of the month and it then resumes its normal sedate easterly progress.

Lunar Occultations

As usual in the table I’ve only included events for stars down to around magnitude 7.0 that occur before midnight. DD = disappearance at the dark limb and RD = reappearance at the dark limb.

Times are all BST.

May	Time	Star	Mag.	Ph	PA °
16^th	22.15	SAO 77971	6.7	DD	90
17^th	23.24	SAO 79131	6.4	DD	101
17^th	23.24	GSC01357 02074	6.0	DD	100
20^th	21.21	SAO 117979	7.0	DD	103
20^th	22.30	SAO 117997	6.8	DD	128

Phases of the Moon for May

Last ¼	New	First ¼	Full
6^th	14^th	20^th	27^th

ISS

There are a large number of evening passes of the ISS this month so I have only included those of magnitude -2 or above. There are many more that are fainter or occur after midnight, the details of which can be found at www.heavens-above.com Please remember that the times shown below are for when the ISS is at its maximum elevation, so you should start looking a few minutes beforehand. Times are all BST.

May	Mag	Time	Alt°	Az.
1^st	-2.2	20.58	27	SSE
1^st	-3.4	22.34	87	S
2^nd	-3.2	21.24	54	SSE
2^nd	-3.2	22.59	77	N
3^rd	-3.4	21.49	89	S
3^rd	-2.4	23.23	46	WNW
4^th	-3.1	20.39	56	SSE
4^th	-3.2	22.14	77	N
5^th	-3.3	21.04	90	NNW
5^th	-3.4	22.39	86	N
6^th	-3.2	21.29	76	N
6^th	-3.1	23.04	57	SW
7^th	-3.3	21.54	88	N
8^th	-3.1	20.44	76	N
8^th	-3.2	22.19	59	SSW
9^th	-3.3	21.09	89	NNW
9^th	-2.2	22.44	30	SSW
10^th	-3.1	21.34	57	SSW
11^th	-2.0	21.59	29	SSW
12^th	-2.9	20.48	55	SSW

Iridium Flares

The flares that I’ve listed are magnitude -3 or brighter because there are quite a few this month. There are a lot more flares that are fainter, occur at lower altitudes or after midnight. If you wish to see a complete list, go to www.heavens-above.com Times are all BST. Remember that when one of these events is due it is often possible to see the satellite in advance of the “flare”, although of course it will be much fainter at that time.

May	Time	Mag	Alt°	Az.
3^rd	22.49	-7	24	NE
6^th	22.41	-7	29	NE
9^th	22.32	-4	35	NE
11^th	20.45	-6	71	ENE
13^th	22.17	-3	42	NE
18^th	21.56	-4	49	NE
23^rd	21.35	-5	57	NE
28^th	23.57	-3	46	SW
29^th	21.08	-7	66	NE

The Night Sky in May

If you look north at around 22.00 BST the Plough is almost overhead meaning that two of the three stars of the Summer Triangle (Deneb and Vega) are grazing the northern horizon. If we use the curve of the handle of the Plough, or the tail of the Great Bear, and extend it we come to the bright star Arcturus in the constellation of Boötes. Just beside Bootes is the obvious crescent of stars that makes up Corona Borealis - the northern crown. If we continue the curved line further we reach the first magnitude star Spica in Virgo.

Returning to the Plough we can use the “pointers” Merak and Dubhe to direct us to the pole star - Polaris. Once this has been found Ursa Minor or the little bear can be identified curving towards its big brother. Between the two lies Draco (the dragon) with its head towards the horizon at this time of year. Drawing a line from the double (Alcor and Mizar) in the handle of the Plough through Polaris and onwards will bring you to the “W” of Cassiopeia, the two lower stars of which point towards the constellation of Cepheus.

Looking south Leo is prominent with the “Sickle” (in the shape of a back to front question mark) and the bright star Regulas at its base. A little to the west of Leo lies the faint constellation of Cancer, and a little further west again is Gemini with the two bright stars Castor and Pollux. If you draw a line through them and continue it for a short distance towards the horizon you come to a small group of stars that forms the head of Hydra the sea serpent or water snake. From the head a line of mainly faint stars makes its way in a south westerly direction passing a little below Spica that we mentioned earlier. Lying between Hydra and Virgo are the two small but reasonably easy to identify constellations of Crater and Corvus.

Brian Mills

NASA’S SPACE PLACE

A Rock Hound is Born

It’s tough to be a geologist when you can’t tell one rock from another. Is that a meteorite or a chunk of lava? A river rock or an impact fragment? Houston, we have a problem!

It’s a problem Spirit and Opportunity have been dealing with for the past six years. The two rovers are on a mission to explore the geology of the Red Planet, yet for the longest time they couldn’t recognize interesting rocks without help from humans back on Earth.

Fortunately, it is possible to teach old rovers new tricks. All you have to do is change their programming—and that’s just what NASA has done.

“During the winter, we uploaded new software to Opportunity,” says Tara Estlin, a rover driver, senior member of JPL’s Artificial Intelligence Group, and the lead developer of AEGIS, short for Autonomous Exploration for Gathering Increased Science. “AEGIS allows the rover to make some decisions on its own.”

Estlin and her team have been working for several years to develop and upload increasingly sophisticated software to the rovers. As a result, the twins have learned to avoid obstacles, identify dust devils, and calculate the distance to reach their arms to a rock.

With the latest upgrade, a rock hound is born.

Now, Opportunity's computer can examine images that the rover takes using its wide-angle navigation camera (NavCam) and pick out rocks with interesting colours or shapes. It can then centre its narrower-angle panoramic camera (PanCam) on targets of interest for close-up shots through various color filters. All this happens without human intervention.

The system was recently put to the test; Opportunity performed splendidly.

At the end of a drive on March 4^th, the rover settled in for a bit of rock hunting. Opportunity surveyed the landscape and decided that one particular rock, out of more than 50 in the NavCam photo, best met criteria that researchers had set for a target of interest: large and dark.

“It found exactly the target we would want it to find,” Estlin says. “It appears to be one of the rocks tossed outward onto the surface when an impact dug a nearby crater.”

The new software doesn’t make humans obsolete. On the contrary, humans are very much “in the loop,” setting criteria for what’s interesting and evaluating Opportunity’s discoveries. The main effect of the new software is to strengthen the rover-human partnership and boost their combined exploring prowess.

Mindful that Opportunity was only supposed to last about six months after it landed in 2004, Estlin says “it is amazing to see Opportunity performing a brand new autonomous activity six years later.”

What will the rock hounds of Mars be up to six years from now? Stay tuned for future uploads!

Learn more about how the AEGIS software works at:

http://scienceandtechnology.jpl.nasa.gov/newsandevents/newsdetails/?NewsID=677

If you work with middle- or high-school kids, you’ll find a fun way to explore another kind of robot software—the kind that enables “fuzzy thinking”—at:

http://spaceplace.nasa.gov/en/educators/teachers_page2.shtml#fuzzy.

Caption:

Opportunity spots a rock with its NavCam that its AEGIS software says meets all the criteria for further investigation.

CONTACTS

Chairman John Vale-Taylor

pjvalet1@btinternet.com

Secretary & Events Phil Berry 01892 783544

phil.berry@tiscali.co.uk

Treasurer Mike Wyles 01892 542863

mike31@madasafish.com

Editor Geoff Rathbone 01959 524727

geoff@rathbone007.fsnet.co.uk

Director of Observations Brian Mills 01732 832691

Brian@wkrcc.co.uk

Wadhurst Astronomical Society website:

www.wadhurst.info/was/

SAGAS web-site www.sagasonline.org.uk

Any material for inclusion in the June 2010 Newsletter should be with the Editor by May 28^th 2010