From: The Lahrs (JohnJan@lahr.org)
Date: Wed Dec 15 1999 - 18:32:12 PST
Message-Id: <4.2.0.58.19991215192955.00b3d260@netmail.home.com> Date: Wed, 15 Dec 1999 19:32:12 -0700 From: The Lahrs <JohnJan@lahr.org> Subject: Fwd: Cheap Solar Observatory experiments.
This is an interesting extension of the Exploratorium's pinhole
experiments. I'll
have to give it a try some time.
John Lahr
Golden, CO
>Date: Wed, 15 Dec 1999 00:46:22 -0100
>To: sciclub-list@eskimo.com
>From: Malcolm <malcolmCF@connectfree.co.uk>
>Subject: Cheap Solar Observatory experiments.
>
>Greetings, I have been a 'lurker' on the list for some time
>and have enjoyed reading about your exploits, I nearly joined
>in with the nostalgia about making explosives in one's youth !
>
>I wonder if my very amateur very cheap method of observing the
>progress of the solar rotation and of the solar ~11year cycle
>might be of interest to y'all ?
>Since the solar eclipse of 11 Aug 99 gave me the idea, I have
>been playing with just a hole and a mirror and am most surprised
>at how well sunspots can be seen with this ultra safe and simple
>method. The effect of limb darkening can also be seen.
>
>Basically it turns your house and garden into a giant
>size pin-hole camera or camera obscura without a lens.
>In all my years of reading stuff on amateur astronomy I never
>came across this method before.
>I will not bore you and take up bandwidth with a long description
>of it here, my attempts at a few web pages should explain how
>it ( MISER ) all came about :-
>
>http://www.homebrewer.freeserve.co.uk/solar/solar.htm
>
>on that page you will find a description and also links to two
>further pages showing :
>
>(page 2) a series of my daily drawings together with professional
>images for comparison ( 20 small jpgs at about 125Kb in total )
>that demonstrates the rotation of the sun and the development of
>sunspot groups.
>Also (page 3) I sometimes update my latest drawing.
>
>Considering that I live in SW England ( 51deg N ) and the sun is now
>low in the sky and usually very weak and hazy, I am very surprised at
>the amount of detail this simple method can show.
>Recently for example I could just resolve two spots 3mm apart in a
>solar image diameter of 140mm. What is that ?
>3/140 ths of 30 minutes of arc = 0.64 m.
>38 sec. of arc ? Hmmm, astonishing ! Perhaps my sums are wrong !
>
>Anyway, have a look and let my know what you think :-)
>
>Malcolm.
>
>
>
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