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Hello Lars,
Thank you for your careful and very thoughtful reading of my book. You raise some very good questions! Of course, contemporary lunar science cannot yet produce definitive answers for everything, but the case for how the lunar maria were formed is pretty convincing. This is probably not the place to go into lengthy detail, but I can certainly try to address some of your questions.
We should bear in mind that the recent Hawaiian eruptions and lava flows were on a microscopic scale compared with the events that created the lunar maria. The enormous energies released in the impacts that created the huge basins at the sites of subsequent mare development would have compressed, shattered, melted and fractured the lunar crust at the impact site. Such a compromised site would have provided a preferential route for the subsequent eruption and flow of magma on to the surface, magma that had been kept molten by the effects of churning in the interior magma ocean and the decay of radioactive elements.
As Wood says, once vented onto the surface the lavas would indeed have flowed relative easily over great distances, being much less viscous than lavas on Earth (the Moon as a whole is made up of less dense material). Also the larger maria at least would have been formed not in one go, but by successive lava flows. This is obvious in the Mare Serenitatis, where the flows of different lavas are obvious even to the eye at the telescope and appear as different colours and shades.
This would all have gone on until the Moon had cooled sufficiently to prevent the eruption of lavas on such a huge scale, (although smaller forms of volcanic activity continued long afterwards).
Thank you again for your interest!
Bill
Hi Alex,
The book is available through normal channels such as booksellers and Amazon, but I’m not sure if it is possible through the BAA shop. I imagine that would require some sort of deal with the publisher. I’ll check with Ann Davies.
Very best,
Bill
Well spotted, Chris! I wanted an image indicating that the book also covered lunar science in the age of spacecraft exploration.
Bill
Hi James,
I’m not sure I can detect what you describe, but I would not expect the effects of libration to be discernible over such a short period. However, the movement of the terminator might be, even at this image scale. Might that be creating the impression of a shift in the position of Humorum?
Bill
Hi Nick,
I have had a Pulsar dome for over three years, and it does the job well. There are no problems with leaks or other significant water ingress, but there is the occasional thin film of condensation on cold metal surfaces. Not really a problem, but I address it with an ELA DD822 Dehumidifier and Laundry Drier bought from Dry-it-Out.com.
http://www.dry-it-out.com/DD822-Graphite-dehumidifier
Running costs are not really a problem – it only needs a quick blast once-or-twice a week. I find it an ideal solution and everything is kept bone dry.
Very best,
Bill
Hi Nick,
That’s a nice edition of ‘The Comet’s Tale’ with a good variety of content. Many congratulations to you and Janice!
Bill
Martin and James,
Congratulations on finding this – and many thanks for half an hour of nostalgia!
Vey best,
Bill
I’m late to this thread because of the Christmas break, but I’m glad that some members were able to catch the occultation. I had all the meteorological conditions described by Alex, apart from the ‘fairly clear sky’ bit…..
Some Lunar Section members have already submitted timings, but I’d be glad to receive further observations of the event.
May I wish you all clear skies for 2016!
Bill
Thanks Nick. Good conditions here in Sheffield too.
The leading edge of the umbral shadow was grey in colour, but the following shadow was copper-coloured and quite dark. Nevertheless, major surface features (e.g. Tycho, Plato, Sinus Iridum and Aristarchus) remained visible throughout as seen through an 80mm ED refractor and my 300mm OMC. During totality the Moon appeared 3D in its star field at low powers through the 80mm OG – a stunning sight.
The colour of the umbra during totality was copper-grey, with the southern limb much brighter. For a time around mid-eclipse the copper colour almost disappeared and the eclipsed Moon appeared grey. Overall, I found this to be a moderately dark eclipse, with the reddish colours rather subdued. I would estimate it at II or I on the Danjon scale, as seen from the Sheffield suburbs.
The total phase ended at about 03.22 UT, with third umbral contact at the limb near Schiller.
Hope others enjoyed it too. I’d be glad to receive any reports and images.
Bill
Hi James,
As you know, I have tried to reply to your query via the BAA Forum, but every time I reached this post, the website logged me out! Don’t know what the problem was, but it only affected your post, so I replied via e-mail. However, things seem to be working today, so in case others are interested, here is my response:
As far as I am aware there is no link between Robert and Walter, but it certainly merits further investigation and I shall be very interested in what you discover. There is an entry on Walter G. in the Biographical Dictionary of Astronomers, but personal information is sparse (see below). There is also an obituary by W.H. Steavenson in the MNRAS, 99(4), 1939. pp. 310-11, but again it gives little away about Walter’s personal life: born in Loughborough in 1856, moved to Finsbury Park when he was seven, joined his father’s business (William Goodacre & Sons) on leaving school, married Frances Elizabeth Evison in 1883.I think you will have to go to ancestry.co.uk to investigate further, if you have not done so already.Sorry not to have more concrete leads.Very best,BillPS: here is the relevant passage from the Biographical Dictionary:“Goodacre was born at Loughborough, but in 1863 the family moved to London, where his father founded a carpet manufacturing business.Walter Goodacre established a branch of the family business in India and visited there frequently for 15 years. He succeeded his father as head of the firm in London, remaining in that position until his retirement in 1929.”
Hi Donald,
Welcome to the BAA from me too – it’s a great organisation and will offer you much in the way of advice and support. The key thing is to get in touch with the directors of the sections that interest you most and take a look at their websites.
You have had some good suggestions already for the sort of observational work you can do with the equipment you have, but I note you have asked about lunar observing too. Your ED80 is an ideal telescope for finding your way around the lunar surface – indeed, it is similar in size to the first telescope used by Patrick Moore. It will show you a great deal without overwhelming you with excessive detail. Along with a good lunar map and some clear and steady skies, it will offer you many hours of exploration.
The ED80 is a serious telescope and it will allow you, should you wish, to do some serious lunar observing. For example, you could contribute to programmes of study devoted to possible changes on the Moon or the distribution of different types of surface formation. Occultation observation is also well within the reach of your telescope. You will find further details of the Lunar Section observing programme on the website at http://www.baalunarsection.org.uk/ (you can download a PDF of the programme from that page). You will also get further ideas from the monthly section circular. This is distributed by e-mail as a free PDF attachment, and I’d be glad to add you to the mailing list if you wish.
Send me an e-mail if you would like me to do that, or if you have any further questions about lunar observation.
Very best,
Bill
Hi Alex,
Yes, there is still great value in drawing the Moon’s surface features, not least to help to familiarise yourself with the Moon’s complex topography and ever-changing illumination. You will find more about possible observing programmes on the Lunar Section website, but feel free to contact me by e-mail if you have further questions. There is a book on techniques for sketching the Moon: Sketching the Moon: An Astronomical Artist’s Guide, by Richard Handy, Deirdre Kelleghan, Thomas McCague, Erika Rix and Sally Russell (Springer, 2012). Hope this helps!
Bill Leatherbarrow
