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Highlands Astronomical Society

Stargazey Pie, May 2005

Antony McEwan's monthly digest of HAS happenings

May 2005 meeting There was a good turnout for the meeting on Tuesday 3rd May, which was nice as the subscriptions were due and it meant that many members were keen to renew their membership. Again, some new faces were seen, so we must be doing something right. Once that hubbub had died down, everyone was ready for the start,

Chairwoman Pauline Macrae opened the meeting with this month’s notices:

The times they are a-changing The format of the monthly meetings will be changing, and quite noticeably. After the tea break there will be a choice of ‘break-out’ groups for people to attend. These will cover various aspects of astronomy, both general and specialised. This month there was a choice of a beginner’s class hosted by Pauline, a filter discussion group hosted by Maarten and Andy, and the option of staying in the main hall to discuss the main presentation given by Dr. Martin Hendry. The discussion groups will be run again (apart from Dr. Hendry’s one) so there will be other chances for people to take part in them. Suggestions for future breakout groups are invited, so please contact a Committee member if you have any suggestions, or add it to the discussion that has been started on the new Message Board.

Observing Sessions There will be observing sessions on Friday 13th and Saturday 14th May. Weather permitting it is hoped these sessions will be used for planetary and lunar observing, offering a chance to see Jupiter, Saturn and the Moon through the Society’s 10” reflector. Contact details are below; please remember good luck charms may be required to keep the clouds at bay on the Friday 13th session...

Friday 13th May Maarten de Vries

Saturday 14th May Trina Shaddick

HAS BBQ & OBS Looking ahead to the balmy days and evenings of August, how does a Barbecue and Star Party sound? This event will be hosted by Simon Urry at his house at Muiryden near Fortrose. Many thanks to Simon for volunteering the use of his barn and garden. It will start at 3.30 p.m. on Saturday 27th August and families will be welcome. Please bring your own food, drink, chair and telescope (if you have one), and let's hope for good weather. Further details about this event will be announced closer to the time.

Child Protection Policy Statement Further to discussions at the AGM in April, a copy of the Society’s Child Protection Policy Statement was on display for members to read. If you would like to obtain a copy please contact Pauline. A copy is also in the Document Library on our website.

Better late than never If you have not already returned your questionnaire, please do so now! The changes being implemented in the Society reflect the opinions of the membership, so it is important that we have as many of these returned as possible.

A Load of Rubbish We were reminded once again to be careful to put cups and other rubbish into the HAS bin only, and to leave any cups containing liquid on the table for proper disposal. Thank you.

SAG-MAG A copy of the Scottish Astronomers Group Magazine was available for perusal at the front table. If you would like to borrow one, please contact our Secretary, Pat Williams.

Message Board Maarten then told us about some of the changes made on the Highlands Astronomical Society website, and particularly our new improved Message Board. This is a much more functional board than the previous one, and enables people to reply to messages left, use different types of text, colours, etc., and even include pictures within their messages. It also shows how many replies have been made to each message, so you can easily see if any new replies have been made since your last visit. Please drop in, have a look and leave a message. After all, it’s your message board.

We are currently getting several hundred ‘hits’ per day on the website and, as a result, now have our first commercial sponsorship banner on the site. The new banner is promoting the 'Guide to the Galaxy' poster being offered by the Sunday Herald newspaper to coincide with the release of 'The Hitch-Hiker's Guide to the Galaxy' film.

Sky At Night Magazine - Society Profile Pat Williams announced there will soon be an extra dose of the Sky at Night available to fans of the television series, in the form of a new BBC 'Sky at Night' magazine. It is intended that the new magazine will be made as relevant as possible to astronomical clubs and societies and will feature forthcoming astronomical events, reviews, news on the latest discoveries, as well as observing guides and tips. Each month an astronomical club or society will be featured, and we are very excited to hear that the first issue will feature our very own Highlands Astronomical Society. Pat Williams has provided information about the Society to the magazine’s producers, including a picture of Chairwoman Pauline Macrae. The magazine will be launched on Tuesday 24th May, and there is a website for it here. Keep an eye open for it in your local newsagents.

Eyes On The Skies We are entering that difficult part of the year for observations when it stays light increasingly longer, so late nights are required if you want to see anything like a dark sky. There are still some interesting objects to observe though.

The Moon presents some promising opportunities this month, and not just for telescopic observers. On the 9th and 10th the nearly new Moon will be very close to Venus, but very low in the west-north-west in mid evening, and will require sharp eyes to spot. On the 16th it will be quite close to the bright star Regulus in Leo. Even better, it will be very close to Jupiter on the night of the 19th, and should present a very appealing sight. This should also be a great photo-opportunity and, if you are lucky enough to be in South America at the time, you might be able to observe the Moon occulting Jupiter. While you're gazing moonward, have a look for an interesting little 22km crater in the Apennine Mountains, which I discovered in conversation at Tuesdays meeting. It has an interesting name - Conon - but is named after a Greek mathematician and friend of Archimedes, not the local Black Isle town…

Saturn is still very observable but is dipping lower into the west by mid-evening. Once Saturn has gone from this season's night skies, the next time we see it the rings will be slightly less open to us so grab a chance to get a good look at them while you can.

Now, while we’re on the subject of staying up late, you may have noticed very bright Vega low over the northern horizon during the last few weeks. Naturally, as the weeks progress, Vega will be climbing higher and bringing with it the constellation of Lyra, along with the Summer Triangle of bright stars Vega, Deneb and Altair. The whole triangle should be up after midnight, so this could be a chance to get an early viewing of the famous Ring and Dumbbell nebulae, in Lyra and Vulpecula respectively, as well as many other ‘summer objects’. The skies will gradually get even lighter over that time of course, but we should get some chances before it becomes too light to find these objects.

While you’re all up and about in the early hours seeking out these things, you may get a chance to see Mars rising in the morning sky at about 4.30 a.m. in the south east. It will be a bit of a challenge to spot it against the glow of the pre-dawn sky, but it will gradually climb higher and higher, working its way through the constellations as summer progresses, until it becomes ‘comfortably’ observable in the evenings of autumn and winter this year. So don’t give up - there’s still plenty to look for in the warm May evenings and mornings.

The Main Event The main talk at the May meeting was ‘Getting the Measure of The Universe’, given by Dr. Martin Hendry. Dr. Hendry is a senior lecturer in the department of Physics and Astronomy, and head of the faculty of Physical Sciences graduate school at Glasgow University. He is very active in promoting astronomy to schools, societies and the general public, and recently won an award from the Royal Society of Edinburgh in recognition of his contributions to the Science Outreach programme.

Dr. Hendry opened by reminding us of something stated in the Hitch-Hiker's Guide to the Galaxy; Space is big. Really big. So big we have had to invent new types of numbers to record the distances. In order to grasp the distances to the farthest objects in the universe, we first had to accurately measure the smallest ones so we had a solid foundation to work on.

This was the basis for the first section of the presentation, in which Dr. Hendry went back in time to revisit the theories of Ptolemy, Copernicus and Galileo, and the ways in which their work contributed to measuring the distances within the Solar System accurately, primarily by using parallax shift and trigonometry. This involved a great deal of measuring and calculation, and included the contribution made by Jean Picard in 1669, when he accurately measured the distance from Amiens to Malvoisine, and calculated from that the curvature of the Earth, and hence its radius. By combining this with findings made by other scientific luminaries, the Astronomical Unit (AU), or mean Earth-Sun distance, would later be calculated.

With these distances established to a reasonable accuracy, the ‘really big’ distances could then be sought out. Of great importance to this task was the work of Henrietta Leavitt, who discovered what is now known as the Period-Luminosity relationship from her study of Cepheids contained within a sample of 1500 variable stars in the Magellanic Clouds. The longer the star's 'blinking' cycle, the brighter it is. Using a Cepheid's known intrinsic luminosity and its apparent brightness, its distance can be calculated. Cepheid variables are now referred to as 'standard candles' and can be used to reliably measure great distances.

Edwin Hubble identified Cepheids in M31, M33 and NGC 6822 and from measuring their distances conclusively proved that they lay well outside our galaxy, although he got the distance to M31 wrong. Later, he and Milton L. Humason used, and expanded on, spectroscopic measurements made by Vesto Slipher, who first used red shifts to identify that objects were moving away from us at great velocities. Hubble found that the spectral lines in Cepheid variables all over the sky were ‘red shifted’, i.e., they were shifted towards the red end of the spectrum, indicating they too were moving away from us. This, combined with his earlier work, resulted in the formulation of Hubble’s Law of 1929, which states that the universe is in a state of expansion.

Major advances have been made using the Hubble Space Telescope, which has allowed us to see farther than ever before, and thus farther back in time as well. If a Galaxy is 20,000 light years away, we actually see it as it was 20,000 years ago, so in effect the large telescopes astronomers use can also be considered to be time machines, allowing us a window onto the distant past of the universe.

So, having measured these vast distances and looked back in time, do we know the ultimate fate of the universe? Current theory suggests the rate of expansion will inexorably continue, with the universe expanding forever. Dark matter and dark energy are fundamental to these calculations, but are still very little understood, so current thinking could easily change as scientists and astronomers learn more and more about the fabric of the universe. Perhaps the answer to ‘What does the future hold?’ is ‘Only time will tell’ after all.

We would all like to extend our thanks to Dr. Hendry for his fascinating, educational and very entertaining presentation and for staying on after the talk to host a further discussion session. We would like to wish him luck too, as in July he will be travelling to the U.S. for a six month professorship, and will be giving lectures on such questions as, ‘Is there life on other planets?’ and ‘Did we really land on the Moon?’

Happy landings to Dr Hendry from the Highlands Astronomical Society.

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