MEETINGS

DON GOLDMAN TALK

        Ian King Imaging arranged a two part talk given by Don Goldman on the 12th of May in the Methodist Church Upper Room.

        Don is CEO and designer of Astrodon Filters in California and although he explained some of the filters he has developed his main object was to talk about imaging; the aims, problems encountered and methods to deal with them.

        The talk was aimed at an audience with a little knowledge of imaging but took the subject to a much higher level.

        Much of Don’s imaging had been done around the world in such places Australia , Sierra Leon and the USA .  His equipment was very impressive and he was able to show images which were in some ways equal to those produced by the Hubble Space Telescope.

        Don’s website is at www.astrodon.com and contains a wealth of advice and also has a gallery of his images; well worth visiting.

MAY MEETING

Phil opened the meeting announcing details of this year’s SAGAS event, details of which following later in the Newsletter.

He then introduced our speaker for this evening.  Peter Gill is the Events Secretary of the Eastbourne Astronomical Society and  Phil had brought Peter to the meeting because there was a certain amount of projection equipment to bring but whilst at Peter’s home, Phil said he was privileged to see a very extensive library on astronomy.  Peter is also an author himself, having written about the Sun.

The Sun   Talk by Peter Gill

Peter Gill has spoken to WAS twice before and it is good to welcome him back again.

He began by saying his interest in astronomy started 40 years ago in London and over that time has developed his interest in various directions and although this time his subject is the Sun his first 35 mm slide was of a patch of deep sky showing thousands of stars.  Of all stars, only one gives us the chance to look closely in detail at it and that is our own Sun.

We looked at a cross section of the sun and Peter gave details of its size and some information on its composition.  At the core the conditions enable Helium to be formed out of two Hydrogen atoms fusing together.  Energy from this process passes through the Radiation Zone which is itself surrounded by the Convection Zone from which this energy is radiated to the surface of the sun.

The composition of the sun is about 77% hydrogen, about 77% hydrogen, 28% helium and the rest made up of heavier elements and is believed to be about 5 billion years old.

Something that interested Peter particularly is that the centre of the sun is so highly condensed that it acts more like a heavy liquid and it has been calculated that it can take as long as two million years for radiation particles to reach the surface due to particles bumping into other things on the way.

At this stage, Peter stressed the care needed when observing the sun and related the story of filters provided with a Japanese telescopes years ago, where the filters fitted over the eyepiece rather than the object lens; the heat built up inside the telescope and it was known for these filters to crack, allowing the full strength of the sun to reach the eye causing permanent damage.

At the centre of the sun the temperature is about 15 million Kelvin which decreases to about 6,000 Kelvin at the surface.  Also the density at the core is extremely high but falls off much more gradually towards the surface.  Helioseismologists have also discovered that the sun actually pulsates.

About the time of Galileo, an astronomer called Harriot noticed dark spots over the surface of the sun although he thought they were in front of the sun.  The first person to record the position of sunspots and believed them to be on the surface was Shiner, a Jesuit astronomer.  He used an assistant with a projection method and fairly accurately recording sunspot positions.

From the position of the sunspots, the rotation of the sun was determined to be about 27 ½ days at the equator.  Peter went on to say that the centre of a sunspot, although appearing to be black is in fact something like the brightness of 30 full moons.

Sunspots usually appear in pairs with opposite magnetic polarities.  The Umbra of a sunspot has a temperature of about 4,000 K and the penumbra about 5,600 K.

Sunspot activity varies over time with a maximum every eleven years and we were shown a diagram of this activity between 1876 and 1954 called the “Butterfly Diagram” because the positions of sunspot appearances against latitude looks very much like a series of butterflies.

  

Image from NASA

Peter mentioned that during a sunspot cycle, very few occur at high latitudes and usually occur within 40 degrees of the sun’s equator.  As sunspot minimum approaches, they first appear closer and closer to the equator; hence the butterfly similarity on the graph.

We were shown a remarkable picture of the granulation structure of the sun’s surface taken at Greenwich Observatory in 1926.  It was estimated that these individual granulations were about 1,000 kilometres in diameter and found to have a life-time of about 20 minutes.

In 1919 Greenwich Observatory organised a trip to South America to photograph a solar eclipse and Peter showed a picture of a huge solar flare.  He also told the meeting that some time before this image was taken, two astronomers, 400 miles apart had observed a solar eclipse in Spain and by comparing their notes they had established that solar flares were in fact part of the sun and not something related to the moon.

Peter spent some time describing the principle of the specroheliograph devised by Edwin Hale and also explained how the spectral band at Hydrogen-alpha wavelengths enable study of the material above the surface of the sun.  The surface has a temperature of about 4,000 degrees Kelvin but at about 75,000 kilometres above the surface, the temperature reaches a million degrees in the rarefied zone known as the corona.

We were show many photographs of the sun at different spectral wavelengths, particularly hydrogen alpha and calcium and Peter pointed out the different activities that could be seen at these different wavelengths.

We were treated to an astonishing sequence of solar eruptions using a 16 mm cine projector showing a film taken at the Lockheed Solar Observatory.  We could see the development of flares, revealing their structure and giving an idea of the timings.  Some filaments could be seen being ejected outwards from the sun and even some towards the earth.

Some of the active areas could be seen to merge over a day or two following a mass ejection but one outstanding sequence showed an eruption on the face followed by in incredible ripple outwards for many millions of kilometres over the sun’s surface.

Back to the 35 mm still projector we saw the most recent images of the sun taken by the TRACE satellite and show some of the most detailed pictures yet.

Peter closed by saying that the sunspot eleven year cycle was discovered in the mid nineteenth century and has been fairly constant but one solar astronomer, looking back through records found that there had been a period between 1745 and 1815 when there were no sunspots, known as the Maunder Minimum, and it was also noted that at this time, the Thames froze over.  The cause of this long minimum is not known at present, but this puzzle concluded Peter Gill’s very absorbing talk.

UNUSUAL NOTES FROM THE SCIENTIFIC WORLD

        Once again John Wayte has been scanning the science world and again has come up with a couple of interesting observations he has discovered.

        Chimpanzees don’t understand Quantum Mechanics; in fact they don’t even know what they don’t understand.  So, are there facets of the universe that we as humans are also completely oblivious?

        John said that Donald Rumsfield in 2002 said “There are known knowns; these are things we know we know.  We also know there are known unknowns; but there are also unknown unknowns – the ones we don’t know we don’t know!  - How similar are we to chimpanzees?

        John’s second little snippet asks “Are we alone?”

        Kepler has observed 1235 possible Exoplanets.  There are 68 Earth size planets; one in the Goldilocks zone (distance and temperature make it possible for life as we know it). There are 288 super-earth size planets, 5 in the Goldilocks zone.  622 Neptune size planets, 38 in the Goldilocks zone and 19 super-Jupiter size planets, 10 in the Goldilocks zone…

        John left us to ponder on that. 

FROM OUR DIRECTOR OF OBSERVATIONS

        Brian Mills continued his A – Z of astronomy with Cepheid Variables, followed by the sky notes for the coming month.  More in the Sky Notes later in the Newsletter.

JUNE  MEETING

        Wednesday 15th June 2011       Telescope Evening.  This is a meeting when we have short talks on various astronomical subjects and there will be demonstrations of using equipment and software.  Members are encouraged to bring their telescopes and talk about what they use them for.

        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 meeting.

        The venue as always is held 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 20th July 2011 – Our own Phil Berry is giving an illustrated talk about “Nebulae”

        There is no meeting in August but again Michael and Claire Harte are allowing us to use Greenman Farm to hold an Astro-barbecue on Monday 29th August 2011.  Details will follow in a later edition of the Newsletter, but this is certainly a date worth putting in your diary.  It has been a great success in the past with telescopes and a bring-your-own-food-and-drink barbecue.

        Wednesday 21st September 2011 – Bob Seaney will be giving a talk about “The Multi-Universe”, a subject we may well have heard of and Bob’s talks are always worth following.

        Wednesday 19th October 2011 – Our Director of Observations gives a talk about “Registax”, the free star programme from the Internet.

OTHER NOTES AND INFORMATION

SAGAS SUMMER EVENT

        This year’s SAGAS Summer Event this year is hosted by Horsham Astronomy Group on Sunday 3rd July 2011 and is to be held at the New Science School at Christ’s Hospital School, Horsham, West Sussex RH13 0LS.

        The programme of talks is:

Prof Louise Harra – The Solar Cycle begins in earnest.

Peter Edwards – Imaging the planets

Alan Smith – Deep sky delights

Paul Money – Images of the Universe.

        There will be trade stands, the Croydon AS Model Solar System and solar observing (white light and Hydrogen-alpha) weather permitting.

        Tickets are £10 SAGAS members (that’s us) and £12 non-members.  Members need to make their own arrangements.  Ticket enquiries to:

alan.sith25@sky.com

        Coffee, tea and soft drinks are available during the breaks but bringing a picnic lunch is recommended.

        Arrival and registration is at 1000 with the first talk at 1030 and the event closes at 1700.

SKY NOTES FOR JUNE

Planets

Mercury suffers a superior conjunction on the 12th of the month and then moves east of the Sun to become an evening object. However, it is so low down and sets so soon after the Sun, that you are very unlikely to see it.

Venus is a morning object but too close to the Sun this month for observation.

Mars at magnitude +1.4 is a morning object in the constellation of Aries and moves into Taurus in the middle of the month. On the last day of June it rises at around 0200 which is two hours ahead of the Sun.

Jupiter is also a morning object rising before 02.00 hrs by the end of the month. It lies on the Pisces/Aries border at magnitude -2.2.

Saturn is still in the constellation of Virgo and well positioned for observation, not setting until the early hours of the morning. In fact Saturn remains in Virgo for the rest of this year, all of 2012, only moving eastwards into Libra in September 2013. At magnitude +0.8 it continues to dim slightly and the rings close to their minimum tilt as seen from Earth. The ringed planet reaches its second stationary point on June 14th after moving retrograde since January, and then continues its direct motion of west to east.

Lunar Occultations

This month I’ve only included one event because all the others are of faint stars or they occur after midnight. However the one I discuss below is quite unusual because it is a “graze”.

Although the moon is carried across the sky with stars (from east to west), it also has a proper motion of its own (13° per day) which appears to us as a slow passage from west to east. For the moon to complete 1 orbit takes just over 27 days, but for it to return to its original place in the sky takes 29½. This is because the Earth has moved a little around its orbit in the meantime.  As the moon moves it sometimes passes in front of stars that just happen to lie in the same line of sight and occults them. These events are called total occultations. However, when a star, as seen from Earth, passes very close to the polar regions of the moon it can disappear and reappear through the lunar mountains and valleys. This is a graze occultation, the timings of which are used for scientific analysis.

The areas over which a graze can be seen form a very narrow line across the Earth’s surface, and on June 8th the line for one graze passes very close to Wadhurst. I’m hoping that we can get a few observers together to try and observe this event and possibly record some timings that will be of scientific value. If you would like to be involved please contact me either via e-mail or by phone using the contact details at the end of this newsletter. The Society has some telescopes that could be borrowed for this event if there is anyone who would like to take part but does not have the necessary equipment.

Date…………… 8th June 2011

Time…………… 23.02 BST (at Wadhurst)

Star……………..57 Leonis (ZC 1590 or SAO 118577)

Mag……………..6.66

Position angle…26°

Northern limit graze

Double star with a companion of mag 8.5

Recommended minimum aperture is 70mm

Altitude of the Sun -12°

Altitude of the star   17°

Azimuth of the star  251° (WSW)

Phases of the Moon for June

New

First ¼

Full

Last ¼

1st

9th

15th

23rd

ISS

Below are details of the passes of the ISS that occur before midnight as seen from Wadhurst and are magnitude -3.0 or brighter. The details of all passes including those visible from other areas 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 and look a few minutes before. Times are in BST.

June

Mag

Time

Alt°

Az.

12th

-3.2

23.33

38

SSE

13th

-3.8

23.56

70

SSE

14th

-3.2

22.44

37

SSE

15th

-3.8

23.06

69

SSE

16th

-3.1

21.54

36

SSE

16th

-3.7

23.29

83

N

17th

-3.7

22.16

68

SSE

17th

-3.6

23.51

77

N

18th

-3.6

22.39

83

N

19th

-3.5

23.01

76

N

20th

-3.6

21.48

84

N

20th

-3.8

23.24

87

SSE

21st

-3.5

22.11

76

N

21st

-3.6

23.46

54

SSW

22nd

-3.7

22.33

89

SSE

23rd

-3.5

22.55

55

SSW

24th

-3.6

21.43

90

NNE

25th

-3.5

22.05

57

SSW

Iridium Flares

The flares that I’ve listed are magnitude -4 or brighter although there are a lot more that are fainter, occur after midnight or at a lower altitude. 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 in advance of the “flare”, although of course it will be much fainter at that time.  Times are in BST.

June

Time

Mag

Alt°

Az.

2nd

22.40

-4

22

WNW

3rd

23.51

-5

44

WSW

4th

22.37

-6

20

WNW

4th

23.12

-4

21

NNE

5th

23.42

-5

44

WSW

7th

23.04

-5

27

NNE

8th

23.30

-8

41

WSW

12th

23.15

-7

37

WSW

16th

22.28

-7

41

NE

16th

23.00

-4

34

W

19th

22.51

-7

30

W

22nd

22.02

-5

50

NE

24th

22.39

-6

24

WNW

26th

22.36

-4

21

WNW

27th

22.40

-5

18

WNW

27th

23.15

-6

24

NNE

28th

21.35

-6

60

NE

30th

21.39

-4

19

NNW

Total Lunar Eclipse (times in BST)

On June 15th there is a total eclipse of the moon, the second half of which is visible from the south of England . The moon rises at 21.15 hrs but is already fully eclipsed by this time as shown by position ‘B’ in the diagram. Totality ends at 22.03 hrs as the moon begins to leave the central shadow cone. From that time until 23.02 hrs the eclipse will be partial as more of the moon moves out of the umbral shadow and into the penumbral shadow as shown in position ‘A’ in the diagram. When the Moon is fully in the penumbra you will almost certainly be unable to spot the difference between this and a regular full Moon. Incidentally this is the night of the next WAS meeting - so we hope to see this event after the meeting is over.

The Night Sky in June (Written for 23.00hrs BST mid month)

Looking north Ursa Major is to the west of the meridian pointing nose down towards the horizon whilst its smaller companion, Ursa Minor is standing on its tail with Polaris, the pole star, at the tip. Now is a good time to identify Draco (the Dragon) as it is at its greatest altitude. The brilliant Capella in Auriga is just visible as it dips close to the horizon, whilst Pegasus and Andromeda are just rising.

In the east all three members of the Summer Triangle have risen with Vega lying due east at this time. Also now coming into view is the collection of small constellations - Equuleus, Delphinus, Sagitta and Vulpecula that all lie within the area bounded by Pegasus, Aquila and Cygnus.

Scorpio lies due south which means the red supergiant Antares is on show. If the air quality is good, see how much of Scorpio you can see before it is lost behind the horizon. Sagittarius and the “teapot” asterism lie just to the east (left) of Scorpio, whilst the bland areas of Ophiuchus, Serpens and Libra dominate this part of the sky. Higher in the sky are Hercules and Corona Borealis plus the brilliant Arcturus in Boötes.

In the west Leo and Virgo are almost setting, taking with them the planet Saturn.

Brian Mills

DEFINITIONS OF TERMS USED IN ASTRONOMY

Cepheid Variables

These are a particular type of very luminous star whose brightness varies in a regular way and are named after delta Cephei although it was actually Eta Aquilae that was identified as the first member of this class in 1784. The reason for their variation in brightness was suggested by Sergei Zhevakin in 1953 when he put forward the theory that ionized helium was a major player in the processes that were taking place in the stars. Importantly helium becomes more ionised the hotter it gets and the more ionised it gets the more opaque it becomes.

When the star is at its dimmest the outer layers are opaque, but as the heat builds up the star expands (in some cases by millions of kilometres) which causes it to cool down. As it cools it becomes less ionised and therefore more transparent which allows radiation to escape. Once this escape has occurred, expansion stops and reverses due to the stars own gravity and the whole process repeats itself.

It was found that the brightness of the star was directly related to the period over which it varied, and because brightness is related to distance it was obvious that they could be used as so called “standard candles” to find stellar distances.

The problem is, a star that appears bright to us here on Earth may actually be either a faint star close by or a bright one a long way away. To overcome this discrepancy astronomers decided to compare the brightness of all stars as if they were a standard 10 parsecs distant from us which gave them what is known as an absolute magnitude as opposed to apparent magnitude (how bright they seem to us in the sky). However, rather paradoxically you need to know how far away a star is in order to work out its absolute magnitude!

The way astronomers got round this problem was to find Cepheid variables close by and measure their distances using the parallax method. This involves measuring how much nearby stars appear to move when viewed against the distant stellar background. These measurements are taken when the Earth is at opposite points in its orbit. Once they had done this and calculated their distances they used the relationships between their luminosity and distance to calculate how far away more distant Cepheids were. It was Harlow Shapley in 1915 who used Cepheids to calculate the size and shape of the galaxy. However the biggest surprise came in 1924 when Edwin Hubble used a Cepheid to measure the distance to M31, the Great Andromeda Spiral, and found that it lay way outside the Milky Way. It was a profoundly important discovery - to find that other galaxies existed that were entirely separate from our own and this laid to rest the “Island Universe” theory.

Brian Mills

NASA’S SPACE PLACE

Milky Way Safari
by Dauna Coulter and Dr. Tony Phillips

Safari, anyone? Citizen scientists are invited to join a hunt through the galaxy. As a volunteer for Zooniverse's Milky Way Project, you'll track down exotic creatures like mysterious gas bubbles, twisted green knots of dust and gas, and the notorious “red fuzzies.”

“The project began about four months ago,” says astrophysicist Robert Simpson of Oxford University. “Already, more than 18,000 people are scouting the Milky Way for these quarry.”

The volunteers have been scrutinizing infrared images of the Milky Way's inner regions gathered by NASA’s Spitzer Space Telescope. Spitzer's high resolution in infrared helps it pierce the cloaking haze of interstellar gas and dust, revealing strange and beautiful structures invisible to conventional telescopes.  The Milky Way Project is helping astronomers catalogue these intriguing features, map our galaxy, and plan future research.

“Participants use drawing tools to flag the objects,” explains Simpson. “So far they've made over a million drawings and classified over 300,000 images.”

Scientists are especially interested in bubble-like objects believed to represent areas of active star formation.  “Every bubble signifies hundreds to thousands of young, hot stars. Our volunteers have circled almost 300,000 bubble candidates, and counting,” he says.

Humans are better at this than computers. Computer searches turn up only the objects precisely defined in a program, missing the ones that don't fit a specified mould. A computer would, for example, overlook partial bubbles and those that are skewed into unusual shapes. 

“People are more flexible. They tend to pick out patterns computers don't pick up and find things that just look interesting. They're less precise, but very complementary to computer searches, making it less likely we'll miss structures that deserve a closer look. And just the sheer numbers of eyes on the prize mean more comprehensive coverage.”

Along the way the project scientists distil the volunteers' data to eliminate repetitive finds (such as different people spotting the same bubbles) and other distortions.

The project's main site:

http://www.milkywayproject.org

 includes links to a blog and a site called Milky Way Talk. Here “hunters” can post comments, chat about images they've found, tag the ones they consider especially intriguing, vote for their favourite images (see the winners at :

http://talk.milkywayproject.org/collections/CMWS00002u

and more.

Zooniverse invites public participation in science missions both to garner interest in science and to help scientists achieve their goals. More than 400,000 volunteers are involved in their projects at the moment. If you want to help with the Milky Way Project, visit the site, take the tutorial, and … happy hunting!

You can get a preview some of the bubbles at Spitzer’s own web site:

http://www.spitzer.caltech.edu/

Kids will enjoy looking for bubbles in space pictures while playing the Spitzer concentration game at:

http://spaceplace.nasa.gov/spitzer-concentration/.

Caption:

Volunteers study infrared images of our galaxy from the Spitzer Space Telescope, identifying interesting features using the special tools of the Milky Way Project, part of the Citizen Science Alliance Zooniverse web site.

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

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 July 2011 Newsletter should be with the Editor by June 28th 2011