MEETINGS

 

COMMITTEE MEETING

 

        Members of the Committee are respectfully reminded that there is a meeting of the Committee on Tuesday the 13th of July beginning at 1930.  The meeting will be at Phil Berry’s house.  Any member of the Society is always welcome to come along but let Phil know first.

 

JUNE MEETING

 

        Being close to the shortest night of the year, this meeting was named the “Open Evening” when members are encouraged to bring instruments and where there will be short talks on various space-related subjects.

        The meeting was introduced by Phil Berry who reminded members that there is to be an Astro-barbecue at the kind invitation of Michael Harte on Saturday the 28th August.  In the past this has been a successful evening and well worth putting in your diary. There are further details later in the Newsletter under Future Meetings.

        Phil then announced that there would be four short talks throughout the evening together with various interesting instruments and aids to astronomy on view and of course, coffee, tea and biscuits.

        John Vale-Taylor our Chairman had provided a very exciting telescope he had made.  It was a version a Newtonian reflector with the main tube of the telescope replaced with a solid bar that supported the main mirror cell at one end and at the other, the diagonal flat reflecting light to the eyepiece assembly and the whole structure being mounted on a sturdy stand.  As would be expected, it was made to a very high standard.  There are many advantages; it is light, the whole of the telescope is accessible and John said he had found very little problem with dew formation.  It certainly was an innovative idea.

        Phil brought his impressive set of 18 x 50 stabilizing binoculars together with his Nexstar 5 Goto Schmidt-Cassegrain telescope.  He also had with him his occultation set-up which uses a tiny but notable Watec imaging camera feeding a ‘text-overlay’ box which superimposes GPS time and position data over the image from a telescope, giving very accurate time measurements when observing occultations and allowing the results to be reviewed at leisure later.

        Two members of the Society brought their Newtonian Reflector and a small refractor to seek advice on setting them up.  Phil Berry was able to demonstrate how to set them up, both equatorially and optically.

        Ian King made everyone’s mouth water when he brought along a fabulous 120 mm William Optics Refractor!

 

        Phil introduced the first of four short talks.  The first was a review of the Stellarium software programme and was given by Geoff Rathbone.

 

The Stellarium view of the Sky

 

        Stellarium is an astronomy software programme that is fun and easy to use at the same time as displaying the data of some 600,000 stars; and what is more the programme is available free on the Internet.

        The programme comes with a choice of real landscapes and is able to display the Cardinal points N, E, S and W.  Even morning fog can be added.  Against the sky it is possible to superimpose both the earth’s celestial equator and the ecliptic.

        Normally the tool bars are hidden but by placing the cursor near the bottom left corner of the screen; they are revealed and allow many facilities to be selected such as displaying the equatorial grid or the alt-azimuth grid.

        Also, during daylight hours the blue of the sky can be removed leaving the stars and planets visible against the black background.  Many of the stars and planets are labelled so it is possible to pick one.  We chose Saturn and zoomed in to show the rings and its larger moons.  It was also possible then to select one of the moons and zoom in on that one showing the phases as they would be at that exact time.

        Selecting a star with the cursor will display its data such as spectral colour, distance, magnitude, precise position and much more.

        It is possible to make the ground invisible and on the evening of the June meeting, this revealed the Southern Cross just a few degrees below what would have been the southern horizon and from here we were able to see the data for Rigel Kent (alpha Centauri) our nearest star at a distance of only 4.39 light years.

        A bit of fun was to change the landscape from an earthly scene to that of Mars.  It was then also possible to change the observer’s location to actually be on Mars.  Looking back towards the Earth system it was possible to zoom in on the moon, showing the far side of the moon’s surface as it would appear from Mars right now together with the correct phase.

        In this demonstration, panning down towards the surface of Mars showed that we were really standing on the Mars lander together with tracks of the buggy going off into the far distance.

        The programme can be downloaded free from: www.stellarium.org

        Select the system you are using on the right hand side of the home page.  At the top of the next page of adverts select “Stellarium” from – “Your Stellarium download will start shortly.  The programme is about 45 Mb but contains two versions, one with and one without “OpenGL2”.  If the programme fails to display fonts, use the “no-OpenGL2” version which was the version demonstrated at the meeting.

 

       

 

The next talk was by our Director of Observations, Brian Mills.

 

An Introduction to Astronomy

 

        With his usual easy style, Brian began by showing the Earth from space, followed by a view of the Earth at night and revealing just how much light is being emitted out into space, with some of the brightest spots from larger cities, and India in particular was easily recognised by its coastal outline.

        We looked at the structure of the Earth from the crust, through the mantle to the liquid core and then the solid core.

        Next we examined the Sun with an internal temperature of 15 million degrees and a surface temperature around 5,500 degrees C although its corona is only visible during an eclipse.

        The bottom left star In the recognisable constellation of  Orion is the bright star Rigel and comparing this with our Sun we could see that it is something like 17 times bigger than the Sun but fortunately at a far greater distance.

        Brian gave a very clear explanation of how the seasons are due to the 23.5o tilt of the Earth’s axis.  He also explained precession and told how the Pole Star will not always help to find the Earth’s north celestial pole but that in a few thousand years time, its place will be more or less taken by Vega.

        We discussed the size of the moon which, although a quarter the size of the Earth is unusually large as an orbiting moon in the solar system.  Also we were shown how features on the surface of the moon are enhanced along the terminator when viewed from Earth.

        Then Brian went on to show how the tides depend on the position of the moon in its orbit and also of the Sun.

        Moving out to the edge of the Solar system we were told that Pluto now is defined as a Dwarf Planet and is more likely to be part of the Kuiper belt.

        Going much further afield Brian talked about our galaxy, The Milky Way, which is thought to be 100,000 light years in diameter and populated with between 200 and 400 billion stars.  This led him to mention M31, the Large Galaxy in Andromeda with a population of something in excess of a trillion stars!

        Brian concluded his talk by describing the differences between refracting, reflecting, cassegrain and Schmidt-cassegrain telescopes and leaving anyone starting out in astronomy craving more.

 

        After coffee, tea and biscuits we enjoyed a further talk by Brian Mills.

 

The Sky Notes for June and July

 

        The major part of the Sky Notes are to be found under July Sky Notes later in the Newsletter, but Brian gave us guide-lines on star-hopping to locate Ophiuchus, Serpens Arcturus and through to the Summer Triangle and we were rewarded with a 15 second exposure photograph taken with an SLR from Brian’s rooftop of a very recent sunset which included the moon and Venus.

        We were also advised of an Iridium Flare (see Sky Notes for July later in the Newsletter) predicted to appear at 2249 tonight in the west.  Truth to tell, we observed the flare precisely as predicted in the June Sky Notes.  It was a particularly bright event with a magnitude of -7.  It lasted for no more than about three seconds but had been well worth leaving the pub for a moment to see it.

 

 

JULY MEETING

 

        Wednesday 21st July 1020 – Steve Jackson from Ashford Astronomical Society will be visiting us and giving a talk on “An Introduction to Radio Astronomy”; a fascinating subject and one that can be explored by the amateur without recourse to the huge expensive dishes we are familiar with. 

        Meetings begin at 1930 although members are invited to arrive any time after 1900 as this is a good time to exchange ideas and discuss problems and relax before the meeting.

        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

 

        Saturday 28th August 2010 – There is no meeting of the Society in August, but as mentioned earlier, Michael Harte is generously inviting us to hold an Astro-barbecue at Greenman Farm.

        This is well worth putting in your diary. 

         In the past some of us have taken along telescopes, binoculars and anything else we think would be useful to see the night sky in late August.

        Any member of the Society is welcome to bring drink and food to cook on a barbecue and then take advantage of the darkening skies to view whatever is in the sky at that time.

        Michael suggests that members aim to arrive about 1900

        There will be further details in the August Newsletter.

 

        Wednesday 15th September 2010 Details to follow

 

        Wednesday 20th October 2010 Details to follow

 

        Wednesday 17th November 2010 – Our own Trevor Grey will be giving a talk entitled “It Is Rocket Science”

 

        Wednesday 15th December 2010Paul Treadaway gives part two of his story about making his own mirror in a talk called “Building the T200 – Part 2”

 

 

OTHER NEWS AND INFORMATION

       

SKY NOTES FOR JULY

 

Planets

 

Mercury suffered a superior conjunction on June 28th and will emerge as an evening object this month although its position will mean that from these latitudes it is pretty much unobservable.

 

Venus is still a brilliant evening object in the west after sunset at magnitude -4.0, although by the middle of the month it will set less than two hours after the Sun. On July 10th Venus passes around a degree north of Regulus (the brightest star in Leo) whilst on the 15th there is a photo opportunity to catch a crescent Moon, Venus, Mars and Saturn in the evening twilight. For interest I have also marked the position of the ecliptic - see the note in the “Definitions” section.

 

The Earth reaches the point when it is furthest from the Sun (Apogee) on July 6th when we will be 94.5 million miles away.

 

Mars at magnitude +1.4 lies on the Leo/Virgo borders and by the end of the month sets just under two after the Sun. On the last day of the month it passes less than two degrees south of Saturn.

 

Jupiter  at magnitude -2.5 is a brilliant object rising just after midnight (BST) at the start of the month, but by the end it is rising at 22.30 (BST) and brightening all the time. A small telescope or binoculars will easily show the four largest moons and should give a hint of the equatorial belts. Or it would do if one of them hadn’t recently disappeared. The Southern Equatorial Belt has vanished (as has happened in the past) and at the same time the Great Red Spot has become more intense. Jupiter has now reached a stationary point before it begins to move retrograde (east to west) against the star background which it will do until mid November when it resumes its direct motion. See the “Definitions” section for more details.

 

Saturn at magnitude +1.1 is still moving slowly eastwards in Virgo with the rings still very close to an “edge on” presentation.

 

Lunar Occultations

Sadly there is only one event for a reasonably bright star that occurs before midnight.

DD = disappearance at the dark limb.

Time is in BST.

 

July

Time

Star

Mag.

Ph

PA °

24th

21.14

SAO 187992

5.6

DD

75

 

 

Phases of the Moon for July

 

Last ¼

New

First ¼

Full

4th

11th

18th

26th

 

ISS

If you want to see the ISS before midnight you will have to look in the early part of the month. I have only included those passes where the International Space Station is of magnitude -2 or brighter although there are more that are fainter or occur at lesser altitudes. The details of all passes 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 be able to see it for a minute or two before and after these times.

Times are all BST.

 

July

Mag

Time

Alt°

Az.

1st

-3.5

22.05

83

N

1st

-3.7

23.40

85

SSW

2nd

-3.5

22.31

77

N

3rd

-3.7

22.58

81

SSW

4th

-3.5

21.49

78

N

4th

-3.2

22.24

45

SSW

5th

-3.7

22.16

77

SSW

5th

-2.0

23.51

21

SW

6th

-3.0

22.42

41

SSW

7th

-3.6

21.34

73

SSW

8th

-2.8

22.00

38

SSW

 

 

Iridium Flares

The flares that I’ve listed are magnitude -4 or brighter although there are a lot more flares that are fainter, occur at lower altitudes or after midnight. If you wish to see a complete list, or obtain timings for somewhere other than Wadhurst, 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.

Perhaps now might be a good time to reiterate what causes an Iridium flare. The Iridium group of communication satellites carry three highly polished antennae which reflect sunlight in a very predictable way. An observer on the ground who happens to be located in exactly the right spot on the Earth’s surface sees one of these reflections as a bright flash that lasts for just a few seconds. Some flares are bright enough to be seen in daylight if you know exactly where to look. The satellites are due for replacement in the next five years, so whether they will still provide flares remains to be seen.

 

July

Time

Mag

Alt°

Az.

3rd

23.09

-4

34

W

6th

23.00

-4

30

W

9th

22.51

-7

26

W

11th

22.48

-7

23

W

13th

22.46

-4

21

WNW

14th

22.49

-6

18

WNW

19th

23.35

-7

37

WSW

23rd

23.21

-4

34

WSW

23rd

23.21

-7

33

WSW

28th

23.08

-7

26

W

30th

23.06

-7

23

W

The Night Sky in July

By 22.00 (BST) mid-month the bright star Arcturus has crossed the meridian along with Corona Borealis (the northern crown). These can be used to find the fainter constellation of Hercules and from there the less conspicuous Ophiuchus and Serpens. In contrast the bright stars of the summer triangle are well above the horizon and Pegasus and Andromeda are just rising. Looking almost due south and close to the horizon you should see Antares, the brightest star in the constellation of Scorpio. Low on the northern horizon Capella should be visible, whilst Ursa Major is to the west of the pole and Cepheus is to the east. The map appears to show Ursa Major the wrong way up but this is because it is drawn looking south and the Plough is past the overhead point. You will need to rotate the map slightly depending on your viewing time.

 

 

Meteors

The Perseid meteor shower begins on July 23rd with maximum not occurring until the night of August 12th/13th. This year is much more favourable than last because the Moon is entirely out of the way around maximum when in the order of 80 meteors per hour are predicted. More about this next month, but if you want to look in the early stages set yourself up on a partly reclined sun lounger facing north east.

 

Total Solar Eclipse

There will be a total eclipse of the Sun on July 11th and although sadly it is not visible from this country, there are bound to be live feeds available on the internet. The eclipse begins at 18.10 BST and ends at 22.57 BST with the track passing over Easter Island.

 

Brian Mills

 

 

DEFINITIONS OF TERMS USED IN ASTRONOMY

 

Last month we looked at some definitions for terms we use in astronomy, and this month I’ve included a few more.

 

 

Greatest Eastern (or Western) Elongation

This refers primarily to the inner planets Mercury and Venus and defines when they are best seen. Obviously the best time for observation is when they are as far away from the Sun as possible and from the diagram you can see that this is when the three bodies form a right angled triangle. When a planet is at greatest eastern elongation it rises after the Sun and is therefore on view after the Sun has set, making it an evening object. It follows that a planet at greatest western elongation rises in advance of the Sun and is a morning object. Not all elongations are the same however because although a planet may be at greatest elongation, this may occur when the ecliptic is close to the horizon and the planet may be in a poor position for observation.

 

 

 

 

 

 

 

 

 

Ecliptic

The ecliptic can be described as the path of the Sun across the sky in the course of a year. However it is could also be described as the plane of the Earth’s orbit around the Sun (see diagram) and because the other planets orbits are almost exactly in the same plane as ours the ecliptic marks out the path of all the planets give or take a degree or so. The Moon doesn’t quite conform to this as the plane of its orbit around us varies by 5° from the ecliptic. It usually crosses the ecliptic twice each month and if it does so at either new or full moon then we will see an eclipse.

At the points where the ecliptic and the celestial equator cross we have the Autumnal and Vernal Equinoxes - the times when day and night are of equal length.

 

 

 

 

 

 

 

Retrograde Motion

Retrograde motion occurs when a planet appears to stop its regular west to east motion and instead head in the opposite direction for a while before again stopping and then resuming its original course. This is nothing to do with the planet at all but is caused by the Earth catching up a slower moving planet and effectively “passing it on the inside” as demonstrated by the diagram.

 

 

 

Brian Mills

 

 

NASA’S SPACE PLACE

 

Black Holes No Joke

by Dr. Tony Phillips

 

Kip Thorne: Why was the black hole hungry?

Stephen Hawking: It had a light breakfast!

        Black hole humour—you gotta love it.  Unless you’re an astronomer, that is.  Black holes are among the most mysterious and influential objects in the cosmos, yet astronomers cannot see into them, frustrating their attempts to make progress in fields ranging from extreme gravity to cosmic evolution.

        How do you observe an object that eats light for breakfast?

“Black holes are creatures of gravity,” says physicist Marco Cavaglia of the University of Mississippi.  “So we have to use gravitational waves to explore them.”

        Enter LIGO—the NSF-funded Laser Interferometer Gravitational-wave Observatory.  According to Einstein’s Theory of General Relativity, black holes and other massive objects can emit gravitational waves—ripples in the fabric of space-time that travel through the cosmos.  LIGO was founded in the 1990s with stations in Washington state and Louisiana to detect these waves as they pass by Earth.

        “The principle is simple,” says Cavaglia, a member of the LIGO team.  “Each LIGO detector is an L-shaped ultra-high vacuum system with arms four kilometres long.  We use lasers to precisely measure changes in the length of the arms, which stretch or contract when a gravitational wave passes by.”

        Just one problem: Gravitational waves are so weak, they change the length of each detector by just 0.001 times the width of a proton!  “It is a difficult measurement,” allows Cavaglia.

        Seismic activity, thunderstorms, ocean waves, even a truck driving by the observatory can overwhelm the effect of a genuine gravitational wave.   Figuring out how to isolate LIGO from so much terrestrial noise has been a major undertaking, but after years of work the LIGO team has done it.  Since 2006, LIGO has been ready to detect gravitational waves coming from spinning black holes, supernovas, and colliding neutron stars anywhere within about 30 million light years of Earth.

        So far the results are … nil. Researchers working at dozens of collaborating institutions have yet to report a definite detection.

Does this mean Einstein was wrong?  Cavaglia doesn’t think so.  “Einstein was probably right, as usual,” he says.  “We just need more sensitivity.  Right now LIGO can only detect events in our little corner of the Universe.  To succeed, LIGO needs to expand its range.”

        So, later this year LIGO will be shut down so researchers can begin work on Advanced LIGO—a next generation detector 10 times more sensitive than its predecessor.  “We’ll be monitoring a volume of space a thousand times greater than before,” says Cavaglia. “This will transform LIGO into a real observational tool.”          When Advanced LIGO is completed in 2014 or so, the inner workings of black holes could finally be revealed.  The punchline may yet make astronomers smile.

 

Find out more about LIGO at: http://www.ligo.caltech.edu/

The Space Place has a LIGO explanation for kids (of all ages) at: http://spaceplace.nasa.gov/en/kids/ligo where you can “hear” a star and a black hole colliding!

 

Caption: 

Laser Interferometer Gravitational-wave Observatory in Livingston, Louisiana. Each of the two arms is 4 kilometres long. LIGO has another such observatory in Hanford, Washington.

 

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 August 2010 Newsletter should be with the Editor by July 28th 2010