WADHURST ASTRONOMICAL SOCIETY

MAY NEWSLETTER 2007

INDEX: MEETINGS, OTHER NEWS, CONTACTS

MEETINGS

APRIL MEETING

Mars Express

Talk given by Gerry Workman at the Society meeting on Wednesday,18 April 2007

The talk this month on Mars complemented that given by Gerry a few months ago. Last time he showed us the journeys of the 2 vehicles, Spirit and Opportunity, on the surface of Mars. This time he gave us a very comprehensive view of the surface of Mars from several of the orbiting satellites.

First we saw a relief map of Mars so that we could get an idea of where the different features occurred. The northern parts are relatively low-lying and flat while the southern region contains the highlands and has more distinct features such as 2 large basins, one of which is 6 miles deep. It also includes the Tharsis region, a great bulge in the surface containing 4 volcanoes and a huge crack, the Valles Marineris.  

We were then taken on a tour of all these regions with slides taken by the satellites.  Some of the pictures were bird's-eye views, looking straight downwards to the surface. Others were oblique views, assembled from a series of shots. The camera had zoomed in giving the impression that a picture had been taken from a low-flying craft skimming the surface.  Some pictures had zoomed right in onto specific features such as a cliff with a landslide or strata, a channel or a crater with an ejecta blanket. 

The big question about Mars concerns the presence of water either now or earlier on when the geological features were forming. Did water cause erosion?  Looking at some of the slides of craters, it was plausible to think that ice under the surface had been melted by the impact. This could have resulted in a slow flow of muddy material spreading around the crater.

There are channels that look as if rivers have flowed down them at some stage. By zooming in on these channels, their beds certainly looked grooved. The grooves may have been formed by flowing water but also they could be the result of slow moving streams of rock and ice similar to a glacier.

Some features, called 'mesas', might be explained by flash floods, the result of subterranean ice melting. In all, we saw over 200 slides showing many features in a wide distribution of geographical regions.  It gave us a very good picture of what to expect if we should ever visit Mars and plenty of ideas for projects to carry out when we got there to test the geological theories!

Joan Grace

POST-MEETING OBSERVATION SESSION

After the April meeting, about 10 members and including Jerry Workman went over to the field that we had kindly been invited to use, to look at the night sky.  Phil Berry had set up his own telescope before the meeting but had to move it in the dark when we got there due to a rogue street lamp.  Phil had a 50mw laser fitted to his Goto scope for identification of the odd mystery star.  We managed to look at Saturn (Nice View) with its rings and moons as well as Venus and then M44, the Beehive Cluster (525 light years away) with Phil's binoculars.  We also looked at M13 the Hercules Globular Cluster 25,000 Light years distant with the 5" Schmidt Cassegrain and finished off with a low power eyepiece view of the Double Cluster in Perseus NGC869 (very pretty).

We finished by 2220.  Some then went home but some went over to the pub...

MAY MEETING

Wednesday 16th May 2007   Nik Szymanek will be talking about important basic facts in an introduction to CCD imaging.  He calls his talk "Pixel Magic" and with his reputation for incredible images this promises to be an excellent talk.

The meeting that will begin at 1930 will be held in the Upper Room of the Methodist Church at the south-east end of Wadhurst High Street, opposite Uplands College.

FUTURE MEETINGS

Wednesday 20th June 2007   This will be an open Telescope Evening.  A number of telescopes will be at the meeting for discussion and demonstration.  Any member able to give a short talk will be very welcome and should contact Phil Berry who would be delighted to hear from them.

Wednesday 18th July 2007   George Satterthwaite will be giving a talk about "George Airy and His Contribution to Positional Astronomy".

August

There is no meeting of the Society in August, but once again, we have been kindly invited to an Astro Barbecue hosted by Michael Harte and his wife at Greenman Farm on Saturday 25th August 2007.

Greenman Farm, Wadhurst is on the south side of the B2099 immediately to the west of the railway over-bridge.  All Society members are invited and Michael suggests that members aim to arrive at 7.00 pm.

You will only need to bring your own food and drink, as everything else will be provided.

In previous years this has been a very enjoyable event and gives members a chance to meet others in a relaxed and pleasant atmosphere.  Members are invited to bring telescopes, binoculars and anything else of interest, but mainly themselves.

Further details to follow.

Wednesday 19th September 2007   George Sallitt will be giving a talk about "Webcams", a subject that will interest a number of members keen to get involved with this cheaper but still satisfying method of imaging.

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OTHER NEWS

SUBSCRIPTIONS

Subscriptions for the coming year became due on the 1st of January 2007.  Subscriptions remain the same as previous years at 15 per member and 20 for two members within the same family.  Cheques should be made payable to "Wadhurst Astronomical Society" and can be presented to the Treasurer, Mike Wyles at the next meeting or can be sent to him by post if that is more convenient.  Mike's address is: Mr. M. Wyles, 31 Rowan Tree Road, Tunbridge Wells, Kent.  TN2  5PZ.

FUTURE OBSERVING SESSIONS

The owner of the nearby field we used for our post-meeting observation session last month has very kindly extended the invitation to use the field in the future and this is something we should discuss at a Society evening meeting fairly soon.

MAY NIGHT SKY

Planets

Mercury becomes visible towards the end of the month at a magnitude of around -1.0 It can best be found by sweeping the horizon ( a little north of west) with binoculars about one hour after sunset.  Don't attempt to do this when the sun is still above the horizon!

Venus shines like a beacon (at magnitude -4.3) in the west, setting some four hours after the sun. Its phase is still gibbous but decreasing whilst its apparent diameter increases.

Mars is still a morning object in southern Pisces (the fishes) close to the border with Cetus (the whale) at magnitude 0.9. It is not ideally placed for observation.

Jupiter at magnitude -2.6 is an evening object in the constellation of Ophiuchus (the serpent bearer) rising at 2245hrs BST by the middle of the month.  Unfortunately, even at culmination, it is still low in the sky at 16.  It's still well worth watching the movements of the planet's four main moons from night to night.

Saturn is still an evening object in the constellation of Leo (the lion) at magnitude 0.5.  It lies a little to the west of the bright star Regulus.  Some WAS members had an excellent view of Saturn through Phil's telescope after the April meeting.

Lunar Occultations

For this month's occultations, I've included events for stars down to about mag 7.  DD indicates that the star disappears at the dark limb of the moon.  All times are in BST.  Sadly there are only two this month that occur before midnight and both on the same day within three minutes of each other.  The second should be particularly easy as the moon is only four days old and the star is fairly bright.

Date Time Star Magnitude Phase
Sun 20th May 22.03 277 Gem 6.8 DD
Sun 20th May 22.06 278 Gem 3.6 DD

Lunar occultation of Saturn

There is also a daylight occultation of Saturn this month.  Times are in BST.  DD means that the planet disappears on the dark limb of the moon whilst RB means it reappears on the bright limb.  The sun will still be above the horizon for the disappearance but will have set for the reappearance.
Date Time Object Magnitude Phase
Tue 22nd May 20.11 Saturn -0.7 DD
Tue 22nd May 21.15 Saturn -0.7 RB

ISS

There are many opportunities to see the International Space Station (ISS) this month but unfortunately they are all in the early hours of the morning. For more details log on to the web-site: - www.heavens-above.com

Advance warning for June 2007

Monday 18th June - daylight occultation of Venus.

Brian Mills

A RARE CHANCE TO SEE AN ASTEROID

4-Vesta is the brightest of the asteroids and reaches opposition on the thirtieth of May when its magnitude reaches +5.4.       Unfortunately the moon is quite close and will make finding the minor planet difficult at that time, but around the twentieth, the moon is well over to the west still and 4-Vesta will still have a magnitude of +5.6, which should make it possible to find with quite small binoculars.  Allow your eyes to adapt to the darkness for a good five minutes and you may even be able to see it with the unaided eye.

At about the twentieth, the asteroid will be to the south-east, in the constellation of Ophiuchus and at about 2200 hrs will be about 2.5 degrees to the south-east of the globular cluster, M107, at azimuth 128 degrees; altitude 10 degrees.  The most reliable way of observing 4-Vesta will be to find it over several nights as it moves slowly to the right through the night sky.

According to some observers, 4-Vesta does change colour very slightly as it rotates.  This change is very small but can be detected by slightly defocusing a pair of binoculars and comparing the colour of the "blob" with the blob of a nearby-by star.  The minor planet makes one revolution in just over five hours.

4-Vesta is 530 km in diameter and its estimated mass is 9% of the total mass of all the minor planets in the asteroid belt put together.  The surface temperature is about -20 degrees C when lit by the Sun but falls to as low as -190 degrees C when unlit.

The first space mission to Vesta is NASA's Dawn Probe which is intended to enter orbit around the asteroid  for 9 months in 2010 -2011.

NASA SPACE PLACE

Clouds from Top to Bottom

By Patrick L. Barry

During the summer and fall of 2006, U.S. Coast Guard planes flew over the North Pacific in search of illegal, unlicensed, and unregulated fishing boats.  It was a tricky operation-in part because low clouds often block the pilots' view of anything floating on the ocean surface below.

To assist in these efforts, they got a little help from the stars.

Actually, it was a satellite-CloudSat, an experimental NASA mission to study Earth's clouds in an entirely new way.  While ordinary weather satellites see only the tops of clouds, CloudSat's radar penetrates clouds from top to bottom, measuring their vertical structure and extent.  By tapping into CloudSat data processed at the Naval Research Laboratory (NRL) in Monterey, CA, Coast Guard pilots were better able to contend with low-lying clouds that might have otherwise hindered their search for illegal fishing activity.

In the past, Coast Guard pilots would fly out over the ocean not knowing what visibility to expect.  Now they can find out quickly.  Data from research satellites usually takes days to weeks to process into a usable form, but NASA makes CloudSat's data publicly available on its QuickLook website and to users such as NRL in only a matter of hours-making the data useful for practical applications.

"Before CloudSat, there was no way to measure cloud base from space worldwide," says Deborah Vane, project manager for CloudSat at NASA's Jet Propulsion Laboratory.

CloudSat's primary purpose is to better understand the critical role that clouds play in Earth's climate. But knowledge about the structure of clouds is useful not only for scientific research, but also to operational users such as Coast Guard patrol aircraft and Navy and commercial ships at sea.

"Especially when it's dark, there's limited information about storms at sea," says Vane. "With CloudSat, we can sort out towering thunderclouds from blankets of calmer clouds. And we have the ability to distinguish between light rain and rain that is falling from severe storms." CloudSat's radar is much more sensitive to cloud structure than are radar systems operating at airports, and from its vantage point in space, Cloudsat builds up a view of almost the entire planet, not just one local area. "That gives you weather information that you don't have in any other way."

There is an archive of all data collected since the start of the mission in May 2006 on the CloudSat QuickLook website at:

 cloudsat.atmos.colostate.edu.

and to introduce kids to the fun of observing the clouds, go to:

spaceplace.nasa.gov/en/kids/cloudsat_puz.shtml.

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

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CONTACTS

Chairman   John Vale-Taylor  pjvalet@tiscali.co.uk

Phil Berry  01892 783544 phil.berry@tiscali.co.uk

Treasurer  Mike Wyles  01892 542863 mikewyles@globalnet.co.uk

Publicity & Website  Michael Harte  01892 783292 michael@greenman.demon.co.uk

Newsletter Editor  Geoff Rathbone  01959 524727 Geoff@rathbone007.fsnet.co.uk

Any material for inclusion in the June Newsletter should be with the Editor by May 28th  2007

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