Laser Pens |
Maidenhead Astronomical Society may use Laser Pens as a pointer during outreach events and talks. Any such use will comply with our Laser Pen Policy, which may be downloaded from here (.pdf)
Essentially, only responsible adults pre-approved by MAS are allowed to use a laser pointer at an outreach event. Children under the age of 18 and non-approved adults are not permitted to use the laser pen at any time. Any member of the public bringing their own device (without pre-approval) is asked not to use it during one of our events (and will be asked to leave if they are not willing to comply with this request).
Future Public Events |
This page is dedicated to events promoted by Maidenhead Astronomical Society aimed at bringing an awareness and appreciation of astronomy to the general public. Almost all of the Events listed here are run by MAS (the few that are not are plainly marked)
Details of future planned events are limited to those open to the general public (Members should look in the Members Only section for details of future events not open to the public - which includes most of our local Outreach activities (schools, cubs, brownies etc)).
Future events are listed in date order, next planned first. Be aware that events can change (usually due to the weather :-) ) so please check nearer the event before making a journey
Note. MAS holds Public Liability Insurance via our membership of Federation of Astronomical Societies. Our Policy Document for 2017-18 is available as a PDF download here
(-) 11 Nov 2019 Transit of Mercury (2nd of pair)
11 November 2019: Transit of Mercury, start 12:35, mid 15:19, ends 16:015 (all times for Reading)
Like Transits of Venus, these occur in pairs, this being the second of the 2016/19 pair. Although Transits of Mercury are less rare than a transit of Venus, the next Mercury pair will not be until 2032/39 (see wikipedia).
For more on this transit, visit the time and date website
This note last modified: 27th Feb 2016 11:09.
(+) 10 Jun 2021 Solar Eclipse - (partial from UK)
(+) 25 Oct 2022 Partial Solar Eclipse
(+) 7 Mar 2025 (and 22) Major Lunar Standstill
(+) 29 Mar 2025 Partial Solar Eclipse
(+) 12 Aug 2026 Solar Eclipse
(+) 26 Jan 2028 annular Solar Eclipse
(+) 1 Jun 2030 annular Solar Eclipse
(+) 28 Jul 2061 Halleys Comet returns
(+) 23 Sep 2090 Total Solar Eclipse - (the next visible from UK)
Reports from our Outreach & Event activity |
Here you will find reports of MAS events held in the last 10 years or so (i.e. since the MAS web site effectively 'took over' from printed newsletters as the primary means of 'reporting back' to the membership). Some details have been removed to allow for public viewing
The Members Only section contains details of MAS History going back to our formation in 1957
(-) 4 Apr 2019 Newlands School (Outreach)
Thursday, 4th April 2019 - Newlands School (Outreach)
Team: Andy (lead), Robin, Steve report by Steve
We were invited to deliver a talk to the 6th form Physics Class on some specific elements of Astronomical telescopes.
The School is just around the corner from my house, so for once I arrived first - and was amazed to find parking places had been Reserved for us directly outside reception ! This was very welcome, especially when it turned put the classroom was at the very end of the main corridor ! Fortunately two of the teachers helped with the unloading and it was managed in only two trips.
As usual, it was spitting with rain when we arrived, so the plan for outdoor solar viewing was shelved.
Andy had prepared a PowerPoint presentation and would lead the talk, whilst Robin and I would mention the advantages of Refractors v's Reflectors whilst showing off our telescopes.
Andy covered basic ray diagrams, how Magnification is calculated and how the minimum angular resolution, the Rayleigh criteria or Dawes Limit, is calculated from the diameter of the objective lens or mirror. He also mentioned how lens refraction leads to chromatic aberration and how this has to be designed out in modern telescopes.
Whist talking about the focal length of the telescope and how the field of view varies with magnification, I mentioned how the Dawes limit prevents Earth based telescopes from seeing the Apollo lander on the Moon.
Then, after last months talk on the Extremely Large Telescope (ELT), when I got home, I decided to run the figures.
Rayleigh criteria worked example - What Diameter of telescope can see the Apollo lander ?
What size (Diameter) of telescope is needed to see the Apollo Lander on the Moon from the surface of the Earth ?
We know from the Rayleigh criteria / Dawes limit, that the limiting Angular resolution (radians) = 1.22 * wavelength / objective Diameter.
If we know what Angular resolution we need, then we can work out the telescope diameter, D = 1.22 * wavelength / Angular resolution.
The Moon, diameter 3,475km (3,475,000m), subtends an (average) angle of 0.528 degrees from the Earth. To get radians, we multiply by Pi/180, so 0.528 degrees = .009215 radians (9.215 * 10^-3).
The Apollo Lander diameter is 9.4m. So the angle subtended by the Lander from the Earth is thus 9.4 * 9.215 * 10^-3 / 3,475,000 = 2.5 *10^-8 (radians)
The Wavelength of Green light is 560–520 nm or approx 540 * 10^-9m
Plugging in the numbers we get D = 1.22 * 540 * 10^-9m / 2.5 * 10^-8
D = 26.43m
... and whilst no existing telescope exists with this Diameter, the ELT will have a 39 meter mirror !
Using the ELT, what magnification and eyepiece focal length is needed to view the Apollo Lander ?
The 39-metre mirror ELT has a focal length 743.4m. What Magnification is needed, using a Plossl eyepiece (which has a standard field of view of 50 degrees) and what is it's Focal length if the Apollo lander is to fill 1% of the True Field of View ?
Mag = Eyepiece field of view (Efov) / required (or True) field of view (Tfov)
We know Efov (Plossl) is 50 degrees, what is the required Tfov ?
Lander Tfov = 2.5 *10^-8 radians
If Lander is to fill only 1% of the eyepiece, then required Tfov (degrees) is = 100 * 180/Pi * 2.5 *10^-8
Required Tfov=1.43 * 10^-4 (degrees)
Mag = Efov / Tfov
Mag = 50 / 1.43 * 10^-4
Mag = 349,065
... OK, a Magnification of more than 1/3rd a million is a tad more than the typical Mag of 50 or 60 I use with my Dobsonian, but why not ?
To calculate the eyepiece focal length (fl) we use Mag = Objective fl / Eyepiece fl
Efl = Ofl / Mag
Efl = 743 / 349,065 (meters)
Eyepiece fl = 2.13mm
... Eyepieces of 2mm focal length do actually exist, however they are not very easy to use, Plossl eyepieces having a diameter that scales to the focal length (so you are trying to align your eye with a tiny glass bead about 2-3mm in diameter :-) )
This note last modified: 8th Apr 2019 11:26.