Northern Sydney Astronomical Society » Events

Transit of Venus Viewing at Practically No Cost

bobsastro — Fri, 04 May 2012 23:21:58 +0000

REWRITTEN FROM THE WEBSITE:

——————————————————————————–
Subject: Transit viewing at practically no cost

I have read about a scheme that was used successfully to view an eclipse. A large wall was in complete shade and a notice invited passers-by who had a hand mirror to stand in the sunlight and reflect the light onto the wall. I do not know how far they would be from the wall but the reflection was close enough to see the progress stage of the eclipse. It is like re-inventing a pinhole camera and decreasing the effects of diffraction at the same time as the “source” is much larger than a pinhole.

My comments on the situation:

What is a pinhole camera? Basically it is a device for getting some light into a dark space with the proviso that the source of the light is small. Being a pinhole in a card does not change the nature of the sunlight so the source does not have to be a hole in something; it can be a small flat mirror or a larger one with most of the surface covered with black plastic adhesive tape and what’s more it would not even have to be circular as long as it is small – see next paragraph. You do not even need a box – you can use a darkened room which has a small conveniently-placed window or even a doorway for the projected beam and the screen can be a wall or a sheet of something with pale colouring inside the room. There is a drawback of course – you might need a distance of 20 to 30 metres from mirror to screen so you may have trouble finding a suitable place for the mirror as the Sun’s position changes unless you have an assistant with a larger flat mirror which puts another part into the light path. Once you find a suitable spot for the small mirror, direct the sunlight from the larger mirror to the smaller one. As time progresses, only the larger mirror would need to be adjusted by tilting it so I guess that the assistant would not be able to view the screen and would need to be relieved now and then to see the progress. The viewers would be inside the darkened room out of the light path.

Is it part of your experience during a partial eclipse [or at least during a partial phase] that you were under a tree, each small gap in the foliage, each with its own shape, produced, on plain ground, a useful picture of the partly covered Sun? In my youth, we had an old garage whose roof was recycled corrugated iron containing many (unoccupied) nail holes . In effect, the old garage was a batch of pinhole cameras. Every hole gave us a very good picture of the eclipse projected on the floor which most certainly was not white or even light coloured and the holes were only reasonably close to circular. This works for the tree because the size of the gap in the foliage is small compared with the distance from the gap to the ground. Here lies the reason that the small mirror in the scheme above does not even need to be round. The passers-by (above) would have had mostly rectangular mirrors. I have not yet tested this projection method so I cannot predict a good size of mirror but I expect that a diameter of 1.5 to two centimetres at 20 to 30 metres should be a starting point.

All sorts of variations are possible. e.g., masking a rear vision screen:
Remove top and bottom of a carton and put a light paper over one of the open parts. Face the other opening towards the mirror so that the box and screen are in the darkened room and viewing is from behind.

Bob Roeth NSAS

NSAS Events for March

bobsastro — Wed, 29 Feb 2012 22:58:50 +0000

For March, we start out with the Theory Group on Tuesday the 13th, 7:45PM. The General Meeting is on Tuesday the 20th, 7:30PM, and our speaker is Nickolas Seymour from CSIRO, who will be speaking on “Radio Astronomy in the WA Bush”. This should be very topical, as the decision on the Square Kilometer Array is imminent. There are also a number of things to discuss in the GM, including the Transit of Venus in June, and a possible Field Trip to Narrabri later in the year. Our meeting venue is Regis Hall, and as usual, visitors are welcome. See you there.

Observing for Feb

bobsastro — Thu, 16 Feb 2012 06:36:09 +0000

Just a reminder for anyone interested that Observing at North Turramurra this month will be tomorrow, Fri the 17th, and next Fri the 24th. Tomorrow’s forecast is not good, so watch this space.

A New Way of Looking at the Sky – Sydney Science Forum Lecture

Chris Anderson — Thu, 16 Feb 2012 01:51:05 +0000

Sydney University’s Science Forum has a free one hour lecture titled “A New Way of Looking at the Sky”, to be presented by Professor Bryan Gaensler on Wednesday 14 March 2012. The talk synopsis is below:

Ever since Galileo first turned a telescope to the sky in the 1600s, the push has been to build telescopes that reveal the wonders of the night sky in ever more detail. Despite all the many discoveries astronomers have made over the centuries, there are still fundamental unsolved problems about the Cosmos. How has the Universe evolved from the Big Bang to the present day? What is the extreme physics that drives the sudden changes we see in the night sky? And what are the Dark Energy and Dark Matter that make up a staggering 95% of the Universe? To make further progress, we need to do astronomy in a different way: instead of peering at tiny patches of stars in detail, we now need to step back and look at huge parts of the sky at once.

Here in Australia, we are now embarking on an exciting journey to develop this new way of looking at the sky. Professor Bryan Gaensler will describe the exciting technology that is taking shape across Australia, and will explain the amazing discoveries that we are making about the Universe through this bold new approach.

More details, plus the registration form can be found here: http://sydney.edu.au/science/outreach/forum/lecture1.shtml

Theory Group on the 14th, and change of venue for GM on the 21st

bobsastro — Mon, 13 Feb 2012 07:25:13 +0000

Just a reminder that NSAS activities restart tomorrow night with the Theory Group at 7:45 at Regis Hall, and that the venue for the GM for next Tuesday the 21st is changed back to the Fr. Mac (sports) Pavillion due to a scheduling conflict. Hope to see you at either/both. If you haven’t paid your membership renewal, I’d suggest doing it tomorrow, as otherwise the Committee will generate a letter asking whether you wish to remain a member.

NSAS Events for February

bobsastro — Tue, 24 Jan 2012 22:00:37 +0000

On Tuesday the 14th the Theory Group will pick up where it left off with “Understanding the Universe”, at the revised time of 7:45 PM. The General Meeting will be at 7:30 PM on Tuesday the 21st. Our speaker for February is Francisco Di Mille from the AAO, who is recently returned from Chile. He and a colleague have been recently in the news regarding their discovery of stellar jets from Sanduleak’s Star, which he will discuss, along with the Magellan Telescope, where he did his work in Chile. All meetings are at Regis Hall, St Ignatius.

Christmas Party Tomorrow Night the 20th

bobsastro — Mon, 19 Dec 2011 07:08:06 +0000

For anyone not checking their emails, the Christmas Party is tomorrow night, the 20th, at Regis Hall, at 7:30PM. The format is to bring a dish, and the Society will supply drinks. See you there.

December Events and Saturday’s Lunar Eclipse

bobsastro — Tue, 06 Dec 2011 23:06:34 +0000

Just to remind those of you who might have forgot, this coming Saturday night the 10th there is a total lunar eclipse visible from Eastern Australia. It starts at 10:45 PM and is at totallity about midnight. Hopefully the weather will be better on the night. The Society will not run any program for this, as it is so late at night.

I’ll take this opportunity to remind you of the events for December. Next Tuesday the 13th will be the Theory Group at 7:45, and on Tuesday the 20th we will have the Society Christmas Party, which will revert back to the old format of “bring a dish”. I’ll get back to you with more details later. All meetings are at Regis Hall, as usual.

NSAS Events for November

bobsastro — Tue, 01 Nov 2011 05:39:47 +0000

NSAS this November will have the Theory Group on Tuesday the 8th at the new time of 7:45. The Nov General Meeting will be Tuesday the 15th at 7:30, and the speaker is David Malin, the famour AAO astrophotographer. If you ever make it a GM, you should make it to this, as David is a fascinating speaker who will talk on the history of astrophotography. All meetings are at Regis Hall, St. Ignatius. Observing this month is Friday the 18th, and would have been on the 25th, however the Field Trip to Coonabarabran will likely take our Observing Officers away, but there could be Observing if someone is available. Finally, the second Field Trip of the year will take a group to Coonabarbran for a tour of the AAO, followed by dark-sky observing with either own scopes or at a commercial observatory. It’s not too late to join up, so just let me know.

NSAS Activities for September

bobsastro — Sat, 03 Sep 2011 00:02:00 +0000

We start off September tonight with the NSAS Public Star Party for the Lane Cove Cameraygal Festival. If you’re not involved, and want to come along, the details are on the NSAS website. Tuesday the 13th the Theory Group will meet at the new time of 7:45. Tuesday the 20th is the General Meeting, where we will vote for the Geoff Welch Prize winner(s), and our speaker is Dr David Frew from Macquarie University. The topic is something related to planetary nebulae, his specialty (details later). The NAG finished up last month for this time around, so we will have to wait for a new group of budding observers next year to start up again. Observing at N. Turramurra this month is the 23rd and 30th.