MEETINGS

COMMITTEE MEETING

        Members of the Committee are respectfully reminded that there will be a meeting of the Committee on Tuesday the 13th of September.  The meeting will commence at 1930 at Phil Berry’s house.

        As always, any member of the Society is very welcome to come along, but please let Phil know to expect you.

ASTRO-BARBECUE

        On Bank Holiday Monday the 29th of August we were guests of Society Life Member Michael Harte at an Astro-barbecue.

        There were six telescopes, set up under what appeared to be clearing skies.  Most telescopes needed setting up from scratch, having been assembled after travelling, but there was one table-top computer-controlled NextStar 4 Celestron that just needed plugging into a battery and then more or less set itself up, ready for final alignment when stars appeared later.

        Two large refracting telescopes were present and four reflecting telescopes including John Vale-Taylor's ingenious skeleton reflector with a large flat mirror enabling viewing from a static sitting position, stars being tracked by clever control of this mirror.  This telescope was recently demonstrated at one of our meetings.

        The main problem of setting up the telescopes was approximate alignment in daylight ready for more precise alignment once the pole star and other stars become visible.

        Also in most cases the finder has probably travelled separately from the main telescope assembly and requires alignment.  First approximation is achieved using an object fairly close but noticeable; usually an obvious television aerial.

        Having found a part of this in the main telescope eyepiece the finder is adjusted to bring it into the central cross.  A tree on the distant horizon makes it possible to refine this alignment; the further away, the less parallax there is between the finder and the main telescope.  Of course, focussing changes a lot with these terrestrial objects.

        At this stage, on my own 11-inch Celestron, I thought I had found the isolated distant lone tree to discover that panning slightly to the left to locate the chimney of a house in the finder didn’t coincide with what could be seen through the eyepiece.  The wrong tree!  Start again…

        At our next meeting there is to be a talk about setting up a telescope.

        Now all we had to do was wait until the stars became visible for that final adjustment.  So, off to the barbecue, where already exquisite smells were permeating through the trees.

        As it became darker, chat turned to what was likely to be seen later; the Milky Way, the Great Andromeda Galaxy, the Ring Nebula in Lyra and so much more.  Some member had also brought predictions of passes of the International Space Station and a couple of Iridium Flares.

        Then looking up, someone saw a small glow in the sky above us; it was the landing lights of a distant aircraft preparing to land at Gatwick some way off.  The significance was that the aircraft could not be seen but the cloud in front of it was blazing.

        Cloud?!

        The whole of the sky was now filled with cloud, although just a couple of stars had been thought to be visible earlier on.  What was so disappointing was that the cloud showed there was almost no reflection of ground-originated light pollution.  A very good observing site on a clear night, as we can vouch from previous years

        Disappointing from an amateur astronomers point of view, it was still a very enjoyable evening and we send Michael Harte our grateful thanks for the opportunity and perhaps hope that he may allow us to return again another year.

FUTURE  MEETINGS

        Wednesday 21st September 2011 – Several short talks under the title, “Aspects of Observation” will illustrate different methods used in observing not only at night but also during daylight hours.  There will also be practical demonstrations.

        This is a change to our original programme.

        Wednesday 19th October 2011 – Our Director of Observations, Brian Mills gives a talk he calls “Point Granny’s Box Brownie at the Stars”; a practical approach to imaging the sky, even with an undriven camera, including a basic introduction to “Registrax”, the free Internet programme.

        Wednesday 16th November 2011 – David Mannion talks to us about “Galileo and 400 Years of Telescopic Astronomy”.  David has three degrees in Astronomy and has been a teacher for 24 years.  He is also co-writer of a book of the same title as his talk to us tonight.

OTHER NOTES AND INFORMATION

SKY NOTES FOR SEPTEMBER

Planets

Mercury reaches its greatest western elongation on the 3rd of the month providing the best morning apparition of the year for the early birds amongst us. It’s visible at a maximum elevation of 10° above the horizon just north of east, and between 0500 and 0530 seems to be the best time to look. Mercury quickly disappears into the solar glare and passes through superior conjunction on the 28th.

Venus suffered a superior conjunction last month and is now moving east of the Sun to become an evening object. However it is too close to the Sun for observation this month.

Earth reaches the Autumnal Equinox on September 23rd. This is the time when the Sun sits on the plane of the Earth’s equator and day and night are of equal length. When this occurs the Earth’s axis points neither towards the Sun nor away from it.

Mars is a morning object on the Gemini/Cancer borders at magnitude +1.4. By the middle of the month it rises at 0130 BST, and because of its comparatively rapid proper west to east motion it still rises around the same time by months end.

Jupiter rises at 2145 BST at the start of the month but by the end this has become 1945 BST. It is unmistakable in the east at magnitude -2.7, moving retrograde (east to west) through Aries where it remains until the end of the year. It will reach opposition on October 29th. Binoculars, if you can support them, will show Jupiter’s four brightest moons. As an example of what you can see I have drawn the view of the moons that you would get at 2200 BST on the night of the 15th.

Saturn is too close to the Sun for observation this month.

Lunar Occultations

        There are only two reasonably bright occultations this month (that occur before midnight) both of which are reappearances. One reason for the dearth of events at this time of year is that in the early evenings the ecliptic, and therefore the Moon, are both low down in the sky.  There are many other events that are either of fainter stars or occur at more unsociable hours. RD = reappearance at the dark limb.  Times are in BST.  

Sept

Time

Star

Mag.

Ph

PA °

18th

2205

51 tauri

5.6

RD

261

18th

2234

56 tauri

5.3

RD

296

Phases of the Moon for September

First ¼

Full

Last ¼

New

4th

12th

20th

27th

ISS

        Sadly there are no passes of the ISS that occur before midnight during September.

Iridium Flares

        The flares that I’ve listed are magnitude -3 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.

Sept.

Time

Mag

Alt°

Az.

1st

2245

-6

14

NNE

2nd

2239

-3

15

NE

2nd

2244

-6

16

NE

3rd

2127

-4

51

ENE

4th

2121

-5

51

E

4th

2237

-5

18

NE

7th

2228

-4

23

NE

8th

2223

-4

23

NE

10th

2054

-7

57

E

11th

2214

-7

28

NE

12th

2209

-6

28

ENE

16th

2027

-3

61

ESE

17th

2021

-3

60

ESE

22nd

2000

-3

62

SE

23rd

1954

-7

62

SE

29th

1927

-8

60

SSE

30th

1921

-4

59

SSE

Advance Warning for October

Draconid Meteor Shower

        There is a suggestion that the maximum of this shower on October 8th could produce large numbers of meteors. The BAA suggests 300 to 600 per hour is possible, whilst the RAS quotes the University of Western Ontario’s figures of around 1,000 per hour. In 1933 and 1946 this shower reached “storm” proportions with estimates of 10,000 meteors per hour being seen. There are no guarantees as this is a very variable and difficult to predict shower but certainly it should be worth a look as soon as dusk falls.

The Night Sky in September (Written for 2200 BST mid month)

        In the north the Plough is approaching its closest to the horizon which means that Cepheus is almost at its greatest elevation. Cassiopeia to the east of the meridian is climbing and Draco to the west of it is sinking. The bright star Capella in Auriga that is just circumpolar from our latitudes is becoming more prominent in the north east. The map below shows the major circumpolar constellations with dotted lines to aid identification once Ursa Major and Polaris have been found.

        If you look towards the east Andromeda (with M31) and Pegasus are fully on show, whilst Pisces has cleared the horizon. Below Andromeda lie the two small constellations of Triangulum and Aries, the latter of which currently hosts the planet Jupiter.

        Looking southwards the Summer Triangle has just passed the meridian although Deneb (in Cygnus) is almost at the zenith. Straddling the meridian we find the little group of constellations - Sagitta, Delphinus and Equuleus that sit approximately between Cygnus and Aquila.

        Finally, in the west Arcturus is close to setting as are the large faint constellations Ophiuchus and Serpens, but Corona Borealis and Hercules are still reasonably prominent.

Occultation Observations

        Following my appeal in the last newsletter to observe total lunar occultations, three WAS members got together on the evenings of August 5th and 9th on Ashdown Forest to see some reasonably bright stars being occulted. On the 5th, cloud concealed the Moon until five minutes after the event, but on the evening of the 9th conditions appeared to be ideal. All three of us, Phil Berry, Ian McCartney and myself were able to find the star easily and follow it without incident until it disappeared. The only minor problem was that some thin, high cloud got in the way just before the event which made it slightly more difficult than it might have been.

        The advantage of extra aperture was obvious when comparing the view through Ian’s 10” Schmidt Newtonian with that through my 5” refractor. Phil was using his 5” Nexstar. On both evenings (despite the first being cloudy) we set up our equipment in the same way that we would have done for a graze occultation, and we agreed that that there was enormous value in that type of practice. Hopefully we may be able to arrange some more group observing although not always necessarily of occultations.

Brian Mills

DEFINITIONS OF TERMS USED IN ASTRONOMY

Elongation

In the information for planets, I often mention the terms greatest eastern and greatest western elongation when talking about the visibility of Mercury and Venus (the inner planets). Greatest elongation doesn’t refer to the moment when an inner planet is actually as far to the west or east of the Sun as possible - it refers to when they appear to be in those positions. If you look at the diagram you will see that greatest elongation occurs when an inner planet, the Earth and Sun form a right angled triangle so that the line from the Earth to the planet forms a tangent with its orbit.

When a planet is at eastern elongation it lies to the east (or left as we look at it) of the Sun, meaning it rises after the Sun and therefore sets after it. This makes it an evening object. Conversely a planet to the west (right) of the Sun rises first and is a morning object, but of course it sets ahead of the Sun.

The elongations of the inner planets vary in their degree of visibility due to the time of year when they occur. This is primarily due to the angle that the ecliptic makes with the horizon.

To demonstrate this I’ve drawn two horizons for mid-March and mid-September, showing the angle that the ecliptic makes at those times, and added a hypothetical Venus. In both instances the Sun is on the horizon and Venus is at exactly the same elongation from the Sun (apparent distance from it) i.e. the distance along the red line from the horizon to Venus is the same. In the first diagram however you can see that Venus is an altitude of around 8° whilst in the second its altitude is nearer to 25°. Obviously in the September example Venus will be higher in the sky before sunrise affording a much better opportunity for observation. If we compare this to evening apparitions then we find the opposite is true, in that the ecliptic makes a more acute angle with the horizon during September.

The term elongation is only applicable to the planets that lie within the orbit of the Earth and not to the outer planets. For them we use the terms conjunction and opposition which I have discussed in previous newsletters.

Brian Mills

NASA’S SPACE PLACE

Solar System Size Surprise
by Dr. Tony Phillips

        News flash: You may be closer to interstellar space than you previously thought.

        A team of researchers led by Tom Krimigis of the Johns Hopkins University Applied Physics Laboratory announced the finding in the June 2011 issue of Nature.  The complicated title of their article, “Zero outward flow velocity for plasma in a heliosheath transition layer,” belies a simple conclusion: The solar system appears to be a billion or more kilometres smaller than earlier estimates.

        The recalculation is prompted by data from NASA’s Voyager 1 probe, now 18 billion kilometres from Earth. Voyagers 1 and 2 were designed and built and are managed by NASA’s Jet Propulsion Laboratory. Aging but active, the spacecraft have been travelling toward the stars since 1977 on a heroic mission to leave the solar system and find out what lies beyond.

        To accomplish their task, the Voyagers must penetrate the outer walls of the heliosphere, a great bubble of plasma and magnetism blown in space by the solar wind. The heliosphere is so big, it contains all the planets, comets, and asteroids that orbit the sun. Indeed many astronomers hold that the heliosphere defines the boundaries of the solar system.  Inside it is “home.”  Outside lies the Milky Way.  For 30+ years, the spacecraft have been hurtling toward the transition zone. Voyager 1 is closing in.

Much of Voyager 1’s long journey has been uneventful.  Last year, however, things began to change. In June 2010, Voyager 1 beamed back a startling number: zero. That’s the outward velocity of the solar wind where the probe is now.

        “This is the first sign that the frontier is upon us,” says Krimigis.

        Previously, researchers thought the crossing was still years and billions of kilometres away, but a new analysis gave them second thoughts.  Krimigis and colleagues combined Voyager data with previously unpublished measurements from the Cassini spacecraft. Cassini, on a mission to study Saturn, is nowhere near the edge of the solar system, but one of its instruments can detect atoms streaming into our solar system from the outside. Comparing data from the two locations, the team concluded that the edge of the heliosphere lies somewhere between 16 to 23 billion kilometres from the sun, with a best estimate of approximately 18 billion kilometres.

        Because Voyager 1 is already nearly 18 billion kilometres out, it could cross into interstellar space at any time—maybe even as you are reading this article.

        “How close are we?” wonders Ed Stone, Caltech professor and principal investigator of the Voyager project since the beginning.  “We don't know, but Voyager 1 speeds outward a billion miles every three years, so we may not have long to wait.”

        Stay tuned for the crossing.

        For more about the missions of Voyager 1 and 2, see:

http://voyager.jpl.nasa.gov/

        Another Voyager project scientist, Merav Opher, is the guest on the newest Space Place Live cartoon interview show for kids at:

http://spaceplace.nasa.gov/space-place-live

recalculating-space.jpg

Caption:

This artist's concept shows NASA's two Voyager spacecraft exploring a turbulent region of space known as the heliosheath, the outer shell of the bubble of charged particles around our sun. Image credit: NASA/JPL-Caltech.

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 October 2011 Newsletter should be with the Editor by September 28th 2011