The Habitability of Planets

Talk given by Dr. Martin Heath at the Society's February meeting on Wednesday 15th February 2006.

      Dr. Martin Heath has recently been involved in a programme on Channel 4 about Alien Worlds, and with this in mind we began an adventure into the search for the possibility of life somewhere else amongst the Solar planets and planets around other stars.

      Up until the middle of the 18th century Martin said that the feeling was held that it was likely that other planets in the Solar System were inhabited, otherwise why would they be there if no-one lives on them.  Although we now know that only the Earth is inhabited at present, it is possible that other planets have had life on them in the past and maybe may have life on them in the future as conditions change within the Solar System as it ages.

      Although certain conditions must be present for life to exist, it is strange that it is impossible to perfectly sterilize anything on Earth at present.

      Martin then showed a slide with millions of stars and posed the question - what is the chance of there not being life on planets around these star systems.  He spoke of Marconi's radio experiments at the Needles on the Isle of White when it had been suggested that some of the received "noise" could well be coming from outer space.  Also other astronomers and scientists, including Carl Sagan had suggested hat there are probably millions of other beings; - but ask the question - where are they?  Do we have to reach a certain intellectual level to communicate with extra-terrestrial life?  Might it be possible that there are bacteria everywhere in the Solar System?  There maybe higher life but without the ability to move as we do.

      He mentioned that our nearest star, Alpha Centauri is travelling relative to us at 22 kilometres per second and would seem to be passing by, perhaps carrying alien life of some kind.

      William Herschel in the city of Bath looked at the moon through his telescopes and wondered if there could be life there.

      Schiaparelli was an Italian astronomer and observed long lines on the surface of Mars, which he called Canali, which means channels or grooves and which many people took to mean constructed waterways.  Astronomer Percival Lowell at Flagstaff in Arizona thought he could see areas of vegetation and deserts on the surface of Mars, which increased the desire to search for life on other planets.

      Martin introduced us to Barnard who was the astronomer responsible for discovering one of Jupiter's moons and also for Barnard's star, one of the Sun's closest neighbours.  If planets could be detected from Earth, then perhaps this was a good place to start although nothing has been detected so far.

      A pair of dwarf stars observed rotating around each other with an orbit whose plane is level with the Earth give the possibility of detecting a planet if measured light from one of the pair was to diminish briefly.  This has not been detected yet.

      We moved to SETI, the Search for Extra Terrestrial Intelligence Institute although Martin did say that public money could no longer be used for this research.  Never the less a great deal of interest is being shown in the work of the institute.

      Having talked about there being virtually no chance of life on the outer planets and after visits to Mars, no evidence for life there had been found and the plate-like structure of the surface of Venus suggested that this planet is geologically dead.

      We were then taken on a tour round the Earth to view the volcanoes of Hawaii looking rather like Olympus Mons on Mars, then to look at the Mid-Atlantic Ridge where Plate Tectonic activity was resulting in Himalayan like structures.  We looked at the cold currents of the Pacific and then on shore we looked at slides of the San Andreas Fault; all showing that there is a lot of geological change going on.  We have developed ways to keep warm or cool, as we need, indicating that the Earth is changing within conditions that support life as we know it. The natural temperature of the Earth is about -20 degrees Celsius and is only higher because of the presence of carbon dioxide.

      Our own planetary system is fairly simple with the moon helping to give the earth its vital seasons. Martin went on to say that it might be possible for a planet to exist in a stable orbit around a pair of orbiting stars provided it was at least 5 times the distance between the stars.

      Another problem could be the life of the star or stars around which any planets might be orbiting.  Sirius and Proycon may only last about 700 million years whereas our Sun will probably last about 10,000 millions years, which is quite reassuring, although on the down side, it will become a Red Giant towards the end of its life, swallowing the Earth!

      An excellent talk although with a warning that during the next century we need to act to preserve life as we know it.

      Those at the meeting will be relieved to know that Martin's rapid departure to catch a train from Wadhurst Railway station with transport provided by Michael Harte was successful!


     Wednesday 15th March 2006  Martin Frey talks about "Great Astronomical Blunders" Food for thought?


      Wednesday 19th April 2006  Our own Ian King tells us about "Instrumentation".

      Wednesday 17th May 2006  Dr. Robert Smith gives a talk with the alarming title of "Things that go Bang in the Night"

      Wednesday 21st June 2006  We are to have a Members evening called "Summer Solstice Telescope Evening" when members are invited to bring their telescopes and any other astronomical equipment and when we get the chance to discuss our interests.  If any member would be interested in giving a short talk, they would be very welcome and should contact either Phil Berry, Ian Reeves or Geoff Rathbone.

      Wednesday 19th July 2006  Gilbert Satterthwaite FRAS will be talking to us about "Sir George Airy's Contribution to Positional Astronomy".  

      There will be no August meeting but Michael Harte is again kindly offering to hold a barbecue on 26th August.  Details to follow.




      Ian Reeves, one of our Secretaries, has been approached by the Eridge Pony Club who have been donated a Celestron 114 telescope complete with tripod.  They feel it is far too good for a jumble sale!  Anyone interested in purchasing it should contact Sue Port direct on 01892 784438 for further details.


      Would any member of the Society be prepared to give a talk on the 20th of February or the 20th of March 2007 in Tunbridge Wells on the lines of "An Introduction to the Sky at Night" or similar title of the Speaker's choosing?  We have been asked by the Soroptomists Society (a group of business ladies) which has a membership of between 25 and 30.

      Would the volunteer(s) kindly advise Ian Reeves?


      Apart from the Spring Equinox at about 0600 on 20th March the sky this Month is dominated, one way and another, by the Moon.

      Right at the end of the month on 29th March there is a total eclipse of the Sun, but only partially visible from the UK. At least one of our members is off to Turkey to witness the event in full and we wish him clear skies.

      In Kent we will be able to see approximately 17% of the Sun's surface covered by the Moon at 1130 (British Summer Time - which begins on Sunday 26th March) and is an occasion still worth observing.  First point of contact for Wadhurst is at 1048 and last contact is at 1222.  There are several safe ways to see this partial eclipse; by projection; through a Mylar solar filter or looking at the shadow effect through a series of holes or on the ground through trees (if there are any leaves at this time of year).  During the last partial eclipse I used our kitchen colander and the result was quite striking.

      As often is the case, the orbit of the Moon at the time of a solar eclipse can result in an eclipse of the moon either two weeks afterward or in this case, two weeks before on the evening of the 14th March.  This is only a Penumbral eclipse which means that the Earth's atmosphere does the eclipsing, not the planet itself, resulting in darkening of part of the Moon's surface.

      Yet again, the Moon sets another notable record this month by being at its lowest altitude at transit since 1950.  On 22nd of March it reaches a maximum of -29 degrees below the ecliptic or just 9.3 degrees above the southern horizon, - although this is at 0530 in the morning!

      Venus is the bright planet in the early morning, rising about 90 minutes before the Sun.

      Mars is now receding from us but is still well placed for observing, as is Saturn, which has just passed opposition.  Saturn's rings are beginning to close as observed from Earth, but we still have until 2009 before they are completely edge on.

      Jupiter rises just after midnight and transit occurs at 0430.  Since it is about magnitude -2 it should be possible to find it in the SSW sky as the Sun is rising.


Micro-sats with Macro-potential

By Patrick L. Barry

      Future space telescopes might not consist of a single satellite such as Hubble, but a constellation of dozens or even hundreds of small satellites, or "micro-sats," operating in unison.

      Such a swarm of little satellites could act as one enormous telescope with a mirror as large as the entire constellation, just as arrays of Earth-bound radio telescopes do.  It could also last for a long time, because damage to one micro-sat wouldn't ruin the whole space telescope; the rest of the swarm could continue as if nothing had happened.

      And that's just one example of the cool things that micro-sats could do.  Plus, micro-sats are simply smaller and lighter than normal satellites, so they're much cheaper to launch into space.

      In February, NASA plans to launch its first experimental micro-sat mission, called Space Technology 5.  As part of the New Millennium Program, ST5 will test out the crucial technologies needed for micro-sats-such as miniature thrust and guidance systems-so that future missions can use those technologies dependably.

      Measuring only 53 centimetres (20 inches) across and weighing a mere 25 kilograms (55 pounds), each of the three micro-sats for ST5 resembles a small television in size and weight. Normal satellites can be as large and heavy as a school bus.

      "ST5 will also gather scientific data, helping scientists explore Earth's magnetic field and space weather," says James Slavin, Project Scientist for ST5.

      Slavin suggests some other potential uses for micro-sats:

A cluster of micro-sats between the Earth and the Sun-spread out in space like little sensor buoys floating in the ocean-could sample incoming waves of high-speed particles from an erupting solar flare, thus giving scientists hours of warning of the threat posed to city power grids and communications satellites. 

      Or perhaps a string of micro-sats, flying single file in low-Earth orbit, could take a series of snapshots of violent thunderstorms as each micro-sat in the "train" passes over the storm.  This technology would combine the continuous large-scale storm monitoring of geosynchronous weather satellites-which orbit far from the Earth at about 36,000 kilometres' altitude-with the up-close, highly detailed view of satellites only 400 kilometres overhead.

      If ST5 is successful, these little satellites could end up playing a big role in future exploration.

      The ST5 Web site at nmp.jpl.nasa.gov/st5 has the details.  Kids can have fun with ST5 at spaceplace.nasa.gov, by just typing ST5 in the site's Find It field.

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



Chairman          Tim Bance                   01732 832745


Secretary         Ian Reeves                        01892 784255

Secretary        Phil Berry                        01892 783544

Treasurer         Mike Wyles                   01892 542863


  Publicity         Michael Harte                       01892 783292

& Web site                    michael@greenman.demon.co.uk

  Editor            Geoff Rathbone                01959 524727


Any material for inclusion in the April Newsletter should be with the Editor by March 28th  2006