MEETINGS

 

COMMITTEE MEETING

 

Members of the Committee are respectfully reminded that there is to be a meeting of the Committee on Tuesday the 13th of April at 1930.  It will be held at Phil Berry’s house and any members of the Society are encouraged to come along, although please ring Phil before hand.

 

MARCH MEETING

 

At the start of the meeting, Phil Berry reminded members that the list for those interested in going to Herstmonceux on Saturday the 15th of May was on the table for names to be entered.  Members will meet will meet at Herstmonceux at 1100 with an introductory talk at around 1300.  We will be looking at some of their telescopes including some not normally open to the general public.  The cost will depend on the numbers going as there is a reduction above a certain number but the cost will not be more than £8.30p.  Visitors would need to provide their own transport.

Members not present at the March meeting can still have their names entered by contacting one of the Committee members and in any case, the list will still be present at the April meeting.

There is also a proposed visit to the Surrey Research Park on Saturday 10th of July, to see the Surrey Technology facility.  This is near Guildford and would be arranged through the Southern Area Group of Astronomical Societies (SAGAS).  If enough members are interested, this would take place from around 1000 to 1630 and would include a tour of the Clean Room facility.  There will be talks; one by Nik Szymanek on astrophotography.  The cost of this visit would be around £10 and again we would need to provide our own transport.

More information about this possible trip will be known nearer the time.

 

Phil then introduced tonight’s speaker, James Fradgely who had travelled all the way from Wimborne in Dorset.  James is a member of the Wessex Astronomical Society and is also a Fellow of the Royal Astronomical Society.  He last visited us in July 2008 when he set us thinking in his talk about “Strange Goings-on with 3 or more bodies in Space”.  Since James has a background in both Biology and astronomy, he is in a good position to set us thinking once again.

 

Life in the Universe

James Fradgley

 

Are we alone?  James said that to this question there were many views but with little knowledge still, people have a gut feeling about it.  Has there got to be Life?

Now that more and more Exo-planets are being discovered, both these questions are frequently being posed.

The danger of looking for life with our limited experience was beautifully illustrated in a cartoon in which two Zorks, standing on their own planet and looking at Earth reckoned they could see a Zork on the face of the Earth if they screwed their eyes up; their own bodies looked like the outline of Europe and Africa.  Rather like humans looking up at our “Man in the Moon”.

In the 1960s SETI (Search for Extra-Terrestrial Life) was being set up and Frank Drake devised a formula known as the Drake Equation, and was to be used to estimate the number of civilizations in our galaxy with which communication might be possible.  The equation took account of such things as stars with planets; the lifetime of communicating civilisations and the fraction of planets where intelligence develops.

James then took us through the development of the Universe from the Big Bang and talked about the requirements for life to thrive as we know it, and the likelihood of complex life elsewhere.

Just after the “Big Bang” hydrogen made up about 75% of the elements and helium, 25% with very tiny amounts of metals.  We looked at the formation of galaxies with our own, the Milky Way being just a very average galaxy.

Hydrogen burnt to make helium; helium burnt to form carbon and carbon burnt to produce heavier elements.

We looked at the Gaseous Pillars of M16, the Eagle Nebula and James explained how shockwaves from supernovae cause dust clouds to condense.

 

 

The Eagle Nebula M16

 

The creation of planets tended to depend on the iron content of their host star.  During this time it is thought that organic compounds began to appear.  James said that hydro-carbons may have been necessary for a pre-cursor for life.

There would probably need to be Earth-like stability in a single star system and no blue-giants near by.

We looked at a graph of Exo-planets showing the size of the planet’s orbit against the eccentricity of the orbit and clearly showing the habitable zone with the Earth fairly close to the centre of this zone.

We looked more closely at the objects orbiting our Sun inside the orbit of Jupiter and James talked about our comparative orbit and how this related to conditions needed for life to form.  He also explained that these conditions depended on the stability of the Sun and then said that it is believed that they will only last on Earth for about another 200 million years.

He talked about the creation of the Moon and how it is thought to have been initiated by a large object colliding with the Earth in our very distant past, tilting the planet’s axis, and now how essential the Moon was to our orbital stability and the creation of the seasons and tides, all thought to be essential for life to develop, although it is thought possible that the Earth-Moon system may become unstable a few millions years in the future.

We considered the likelihood of a sizeable object hitting the Earth.  It appears that material is landing on the planet all the time but it is too small to be noticed most of the time.  Then there is always the alarming chance that we might be hit by something so large that the Earth would be sterilized of all life!

The first signs of the biological conditions necessary for life are thought to have been created 3.5 billion years ago.  Life could have started spontaneously on Earth or through Panspermia, where life could have been created elsewhere in the Universe and then been transported here through space.

Water existed on the Earth and nucleic acids were forming although the oxygen content of the atmosphere was very low until about 2.5 billion years ago when a great oxygenating event occurred.

Complex life started to develop about 2.1 billion years ago.  Radioactivity diminished at the surface of the Earth and multi-cellular organisms began to appear.

About 375 million years ago in the Devonian Period, a fish called the Tiktaalik appeared and was able to survive out of water.

On a 12 hour clock face, James showed just how life on the Earth had developed with the first signs appearing about 2:30.  At about 6:30, complex life began to appear and the dinosaurs became extinct at about ten to twelve.  Finally the first modern humans appeared with a third of a second left before 12:00.

To end, James returned to the Drake Equation and going through each of the terms, concluded that life is very likely to exist elsewhere in the Universe but SETI is probably not going to get anything…

Again he gave us plenty to think about and one or two things to worry about as well.

We were left with one final slide of the moon being traversed by a formation of what looked very much like our idea of flying saucers!

 

After coffee, Geoff Rathbone gave a short introduction to basic types of telescope mounts.  Following this, Brian Mills gave an introductory talk about Planets.

 

Introduction to the Planets

 

The word planet comes from the Greeks who followed the movements of the planets and called them “wanderers”.

The first questions to ask are “what is a planet and who decides”? The answer is that the body that decides what constitutes a planet and what doesn’t is the International Astronomical Union (IAU). This is a body (formed in 1919) made up of professional astronomers who meet in a General Assembly every three years - the next is in Beijing in 2012. Their aim is to promote and safeguard the science of astronomy in all its aspects through international cooperation.

The IAU formed a committee to make recommendations on the definition of a planet and they duly reported back to the 2006 General Assembly with their proposals.  At this point we need to understand why a debate was needed on the subject at all since for a great many years there had appeared to be no disagreement.

Two things that hastened a debate about planetary definition were:-

 

1.      The discovery of Charon in 1978. This is Pluto’s satellite and, when it was found, its orbital period was used to calculate Pluto’s mass which turned out to be considerably less than expected.

2.      Eris was discovered in 2005 in the Kuiper Belt. This is a Trans-Neptunian body (one that lies beyond Neptune’s orbit) that was found to be 27% more massive than Pluto. Today at least 1,000 Kuiper Belt objects are known.

 

However, there had been a much earlier discussion which began in 1801 following the discovery of Ceres (by Piazzi at his Palermo observatory) in what became known as the asteroid belt.  It was dubbed the “missing planet” because of the Titius/Bode Law of 1772 that used a mathematical formula to show the distances of the known planets from the Sun.  This formula fitted the facts quite well apart from the space between Mars and Jupiter where the law said another planet should exist.  However when you extrapolate the formula out as far as Pluto serious errors appear.  Ceres was initially classed as a planet but other discoveries quickly followed of Pallas (1802), Juno (1804) and Vesta (1807).  By the mid 1850’s the number was up to 23 and astronomers began to catalogue them separately and called them “Asteroids”.  Following the discovery of Vesta it was 38 years before the next body was found (Astraea in 1845) after which discoveries came thick and fast.

The early discoveries were made in Poland, Germany and Italy but none in the UK until the Englishman John Russell Hind found ten in the years 1847 to 1854.  Hind had worked for the Astronomer Royal, Airy, but left Greenwich to work at a private observatory in London.  He is celebrated by a lunar crated and, fittingly, the asteroid 1897 Hind named after him.  By the end of the century 452 asteroids had been found and named.

To return to the IAU General Assembly of 2006, they eventually decided after much debate that a body would only be classed as a planet if:-

1.      It was a celestial body in orbit around the Sun.

2.      It was massive enough to have become generally spherical due to its own gravity.

3.      It had cleared its own neighbourhood or orbital zone.

 

This meant that we now only had 8 planets because Pluto was not considered to have cleared its own neighbourhood.  It also meant that a classification had to be found for Pluto and other bodies.  Hence the name Dwarf Planet was adopted for a body if:-

 

1.      It was a celestial body in orbit around the Sun

2.      It was massive enough to have become generally spherical due to its own gravity

3.      It had NOT cleared its own neighbourhood or orbital zone and was NOT a satellite.

 

All other bodies in the Solar System (except satellites) then became “Small Solar-System Bodies” (SSB’s) including comets.

 

This is the current state of play although the IAU is still in the process of making decisions as new discoveries are made.

 

Brian Mills

 

 

APRIL MEETING

 

Wednesday 21st April 2010– Ashford Astronomical Society is a fairly new but very active society and one of their members, Dave Styles is coming to talk to us about “The Ice Giants”.

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 19th 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.

 

Wednesday 16th June 2010 – Society Open Evening when members are invited to bring telescopes and other items of astronomical interest.  The meeting is open to visitors and it has been a chance in the past to show local interested members of the public what we do and encourage them to join us on a more regular basis which they have done by becoming members themselves.

 

 

OTHER NEWS AND INFORMATION

 

 

SUBSCRIPTIONS 2010

 

We have now entered a new session of the Society and again, 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 always welcome.

Subscriptions can 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

 

 

SKY NOTES FOR APRIL

 

Planets

 

Mercury has its most favourable evening apparition of 2010 during late March and early April, reaching its greatest eastern elongation on April 8th. On this date it’s magnitude will be +0.1 (although it will have been at its brightest around March 25th) and will set around an hour and a half after the Sun. Venus can be used as a guide to locate Mercury as shown in the diagram.

 

 

  

 

Venus is a brilliant evening object, visible at magnitude -3.8 in the west after sunset. By mid April it will set two hours after the Sun and on the 16th the crescent Moon will be in the same area of the sky to aid identification. See diagram below.

 

Mars is visible as soon as darkness falls and throughout the night until around 05.00 BST by the middle of the month. At magnitude +0.4, in Cancer, it is dropping in brightness and apparent size and will continue to do so until it disappears from our view in July.

 

 

Jupiter is still not visible to us having undergone a conjunction with the Sun on February 28th.

 

Saturn at magnitude +0.7 is still moving retrograde (westwards) in the constellation of Virgo. It continues in this direction until June, after which it will resume its regular easterly journey although it will remain in Virgo all year. It is easily identified (even before Spica and Virgo have risen) a little below the hind quarters of Leo.

 

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.

 

 

Apr.

Time

Star

Mag.

Ph

PA °

16th

22.02

SAO 75917

6.9

DD

72

19th

20.52

SAO 78210

6.6

DD

74

19th

21.13

SAO 78222

6.9

DD

140

19th

23.44

SAO 78349

6.1

DD

93

24th

23.49

SAO 118634

5.9

DD

185

 

 

Phases of the Moon for April

 

Last ¼

New

First ¼

Full

6th

14th

21st

28th

 

 

ISS

There are only four evening passes of the ISS this month so I have included all of them. There are many more that 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.

 

 

Apr.

Mag

Time

Alt°

Az.

29th

-1.5

21.06

14

SE

29th

-1.6

22.39

23

SW

30th

-2.5

21.28

29

SSE

30th

-2.0

23.02

32

W

 

 

Iridium Flares

The flares that I’ve listed are magnitude -4 or brighter because there are so many 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.

 

 

Apr

Time

Mag

Alt°

Az.

3rd

21.46

-8

43

ENE

4th

20.04

-8

69

SE

6th

22.43

-6

14

NE

7th

21.31

-5

51

ENE

8th

22.40

-6

18

NE

10th

22.38

-7

21

NE

11th

22.39

-6

24

NE

12th

21.10

-5

57

E

12th

22.35

-7

25

NE

15th

22.26

-4

30

NE

16th

20.55

-4

64

E

17th

20.49

-8

64

E

22nd

20.27

-5

72

E

25th

21.54

-5

47

ENE

28th

23.00

-6

15

NNE

30th

22.58

-4

19

NNE

 

 

Meteors

The April Lyrids are active from the 19th to the 25th with maximum occurring on the 22nd when the ZHR is expected to be between 10 and 20. The diagram below is drawn for the night of maximum at around 22.00 BST. The position of the radiant (the point in the sky where the meteors appear to radiate from) is marked by an “R”.

 

 

 

Brian Mills

 

 

NASA’S SPACE PLACE

 

Deadly Planets

By Patrick L. Barry and Dr. Tony Phillips

 

        About 900 light years from here is a rocky planet not much bigger than Earth. It goes around its star once every hundred days, a trifle fast, but not too different from a standard Earth-year. At least two and possibly three other planets circle the same star, forming a complete solar system.

        Interested? Don't be. Going there would be the last thing you ever do.

        The star is a pulsar, PSR 1257+12, the seething-hot core of a supernova that exploded millions of years ago. Its planets are bathed not in gentle, life-giving sunshine but instead a blistering torrent of X-rays and high-energy particles.

        "It would be like trying to live next to Chernobyl," says Charles Beichman, a scientist at JPL and director of the Michelson Science Center at Caltech.

        Our own Sun emits small amounts of pulsar-like X-rays and high energy particles, but the amount of such radiation coming from a pulsar is "orders of magnitude more," he says. Even for a planet orbiting as far out as the Earth, this radiation could blow away the planet's atmosphere, and even vaporize sand right off the planet's surface.

        Astronomer Alex Wolszczan discovered planets around PSR 1257+12 in the 1990s using Puerto Rico’s giant Arecibo radio telescope. At first, no one believed worlds could form around pulsars—it was too bizarre. Supernovas were supposed to destroy planets, not create them. Where did these worlds come from?

        NASA’s Spitzer Space Telescope may have found the solution. In 2005, a group of astronomers led by Deepto Chakrabarty of MIT pointed the infrared telescope toward pulsar 4U 0142+61. Data revealed a disk of gas and dust surrounding the central star, probably wreckage from the supernova. It was just the sort of disk that could coalesce to form planets!

        As deadly as pulsar planets are, they might also be hauntingly beautiful. The vaporized matter rising from the planets' surfaces could be ionized by the incoming radiation, creating colorful auroras across the sky. And though the pulsar would only appear as a tiny dot in the sky (the pulsar itself is only 20-40 km across), it would be enshrouded in a hazy glow of light emitted by radiation particles as they curve in the pulsar's strong magnetic field.

        Wasted beauty? Maybe. Beichman points out the positive: "It's an awful place to try and form planets, but if you can do it there, you can do it anywhere."

        Find more news and images from Spitzer at:

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

In addition, The Space Place Web site features several games related to Spitzer and infrared astronomy, as well as a storybook about a girl who creamed of finding another Earth. Go to:

http://tiny.cc/lucy208.

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

 

 

Caption:

Artist’s concept of a pulsar and surrounding disk of rubble called a “fallback” disk, out of which new planets could form.

 

 

CONTACTS

 

ChairmanJohn Vale-Taylor

pjvalet1@btinternet.com

 

Secretary & EventsPhil Berry   01892 783544

phil.berry@tiscali.co.uk

 

TreasurerMike Wyles   01892 542863

mike31@madasafish.com

 

EditorGeoff Rathbone   01959 524727

geoff@rathbone007.fsnet.co.uk

 

Director of ObservationsBrian Mills   01732 832691

Brian@wkrcc.co.uk

 

Wadhurst Astronomical Society website:

www.wadhurst.info/was/

 

SAGAS web-sitewww.sagasonline.org.uk

 

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