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 Post subject: Night-time Sundial
PostPosted: Wed May 23, 2018 11:20 am 
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Joined: Wed May 23, 2018 10:51 am
Posts: 2
Hello all,

I was advised to join the SPA, and what a wonderful source of "all-you-need-to-find-out" it is. I have designed a sundial to assist me in what I was trying to prove, which allows you to see the time in cities throughout the World relative to the UK's time; or any country vis-a-vis any other country. It can also be used to tell you what you can expect to see in the night sky at any time of the year. Therefore, it can be used to help find planets, constellations etc., and when you can see them - or not.

As I can not afford to even try to patent the idea, I have given the idea away. I have incorporated the materials list and building instructions in the Appendix of a book which is sold by Amazon.

I am currently sounding out schools, scouts, guides et al, as it can be (I think) a useful device to assist in introducing astronomy. It also is an ideal device to make in a group project. Enough of that.

What I want to know is "is there a similar beast out there?" If so, I would like to share notes and experiences. I look forward to 'meeting' some folks for discussion.

Regards, Mac1937.


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 Post subject: Re: Night-time Sundial
PostPosted: Wed May 23, 2018 7:02 pm 
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Joined: Mon Jan 18, 2010 9:25 am
Posts: 5296
Hi Mac.
I can only think of planispheres or many books that show what is to be seen throughout the year.

How does your device deal with countries that have times differing by half hours, such as India? or 1/4 or 3/4 hours like some Pacific island nations?

General sundials may have latitude problems.
And the equation of time, which differs up to 14 or 16 minutes from clock time.

Is it for a fixed epoch?

Planets wander around, how does it deal with this?

Regards,
David


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 Post subject: Re: Night-time Sundial
PostPosted: Thu May 24, 2018 4:35 pm 
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Joined: Fri Dec 03, 2004 9:58 pm
Posts: 3540
Location: Wellingborough
Hi Mac, and Welcome!

Like David, I can't really visualise the device you are describing. Is there any more information, or a reference to the book you mentioned?

regards,

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 Post subject: Re: Night-time Sundial
PostPosted: Fri May 25, 2018 1:26 pm 
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Joined: Wed May 23, 2018 10:51 am
Posts: 2
Brian wrote:
Hi Mac, and Welcome!

Like David, I can't really visualise the device you are describing. Is there any more information, or a reference to the book you mentioned?

regards,


Hello Brian.

Thanks for welcome and interest. I seem to be having difficulty in sending replies. I hope this is not the second time you've received this! I think the best way to respond to you and David Frydman, is to point you to a book on Amazon. It's called "Time Flies - Really?". It costs £5 (paperback) ... and it's written by me. :oops: It is aimed at schools, scouts, guides, cadets et all. I see it as an educational device and ideal for group projects.

The book's Appendix covers, in a descriptive form with the maths kept simple - as not everyone who has an interest in astronomy has a grounding in maths/physics - the materials list and instructions to build and use the sundial.

To briefly answer your question regarding night-time use. This is manifested by placing a separate ring around the base of the sundial covering the solar times around the edge. The ring replaces these solar times with entries containing the Right Ascension number, the associated month and constellation. Finding the time anywhere on Earth, is by using a rotatable Earth disk (flattened at the Equator) and a fixed 24-hour clock around the Earth disk. This 24-hour clock is an extension of the Right Ascension principle applied around the Earth in the same manner as the RA numbers are around the Celestial Sphere. As far as I'm aware, I have researched but cannot see this idea used anywhere else.

I have decided to give the idea away as I could not afford to patent the idea. I have Trademarked the picture of the device so that I can use it in sundial-related mail.

Let me know if you want more expansion, but the book should explain it all; it's only 146 pages including the ToC! Hopes this gets to you, could you pass it on to David Frydman please?

Regards, Mac.


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 Post subject: Re: Night-time Sundial
PostPosted: Fri May 25, 2018 4:03 pm 
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Joined: Mon Jan 18, 2010 9:25 am
Posts: 5296
Hi Mac,
I don't buy anything on the internet, but others can maybe comment when they have seen your book.

Regards,
David


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 Post subject: Re: Night-time Sundial
PostPosted: Sat May 26, 2018 5:37 am 
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Joined: Sun May 11, 2008 6:11 pm
Posts: 3246
Location: Portslade, Sussex Lat 50deg 51min Long 0deg 13mins West
If this book has already been printed, and is available now from Amazon, maybe your best shot would be to send a free promotional copy, (after all it is only £5) to the SPA editorial staff for review in "Popular Astronomy" or perhaps to the "Sundial Society", although the term "Sundial" does seem odd when it is to be used at night! regards maf


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