Happy New Year

I hope you had a good Christmas and that 2008 proves to be a prosperous and happy year for you. Let's hope for clear skies and a few unexpected delights such as last year's brightening of Comet Holmes to liven up our observing.

Campaign for Dark Skies

Clear skies are so much better if they are also dark. The people running the Campaign for Dark Skies (CfDS) are working very hard to reduce light pollution and improve our views of the heavens so I hope you will take a few minutes to help them. They are conducting a survey on light pollution and problems which they will publish and present to DEFRA. You can find the survey at http://www.britastro.org/dark-skies/survey/index.html

CfDS has been remarkably successful in many areas. They work quietly but effectively with the aim of improving lighting rather than just trying to reduce it. They accept that lighting is needed and place emphasis on having the right lighting in the right place at the right time. Even if you are not an astronomer their work is still worth supporting as it will lead to a reduction in wasted light and energy as well. By completing the survey you will help them be even more effective.

Star Parties

We will continue our star parties into 2008, the next one being on Tuesday 15th January from 7 to 9 pm. As usual we shall have a cloudy programme to fall back on if we're not able to observe, but hopefully you will be able to try a range of telescopes and get a guided tour of the sky.

The theme for the 15th is 'The Moon and Mars' and subsequent parties will be held on alternate Tuesdays.

Arizona Sky Village

I'm travelling out to the village on 15th January to spend a couple of weeks there and to look at a new site just across the border in New Mexico that is being developed for astronomy and horse-riding. It is just a few miles from the ASV in the Peloncillo Mountains which offer superb trail riding as well as the same dark skies as the ASV. New Mexico's largest vintner is planting a large portion of the ranch with vines and one of North America's leading equestrians is helping to set up the horse riding.

The project is in its very early stages so there is an opportunity to invest at pre-planning prices to get an excellent return on your investment. If you are interested, please contact me for further details.

Wide-field Imaging with Hyperstar

If you replace the secondary mirror in a Schmidt-Cassegrain Telescope by a correcting lens you can get a very fast, wide-field focus which is ideal for imaging. This is what the Hyperstar does and we have supplied one recently to Steve Loughran for his 8-inch Celestron SCT. When the weather clears Steve will be giving it a thorough workout and we will bring you some of his results.

The images I've seen so far from Hyperstar-equipped telescopes are stunning, and many of them have been taken with alt-az mounted scopes because exposure times are much shorter than at a conventional f/10 focus. For example, 15 seconds at a Hyperstar f/1.8 focus is equivalent to over 15 minutes at f/10.

If you would like to find out more about Hyperstar please see http://hyperstar.green-witch.com  Versions are now available for some Meade telescopes as well as Celestron 8, 11 and 14-inch SCTs. If you would like to see a Hyperstar we have the 8-inch version in stock.

International Olympiad on Astronomy and Astrophysics

 Keith Tritton was telling me about his recent trip to Thailand when I met him on New Year's Day. Keith was Head of Astronomy at the RGO when I was Head of Engineering and at one time had worked in Thailand and had been instrumental in setting up an observatory there with a 16-inch telescope made by Jim Hysom. Many of Keith's former students met him during his visit and he attended part of the first International Olympiad on Astronomy and Astrophysics held at Chiang Mai. It is a competition for high school students but Keith was impressed by the standard which he judged to be university level.

I looked up the IOAA on the web and found the questions the students had been expected to answer. They are quite demanding and I recommend you take a look to see how you would have got on. The web site is at http://ioaa.info/ioaa2007/

Looking South at 10 pm (from Dry Drayton)

Our southern meridian runs from Auriga the charioteer with its brightest star, Capella, down the right-hand sides of Orion and Lepus the Hare. Just to the right of the meridian is the head of Taurus the Bull. Mars is also in Taurus and approaching the meridian from the left; it will be on the meridian around 11 pm.

Capella is the closest first-magnitude star to the North Celestial Pole (Polaris is second-magnitude) but is actually two yellow stars orbiting each other at a distance about two thirds of the Earth-Sun distance, ie less that 100 million kilometres. It is usually classified as a non-eclipsing spectroscopic binary which means that neither star passes in front of the other from our viewpoint and the two stars can only be distinguished by looking at their spectra, not by imaging. However, in September 1995 the COAST group at Cambridge produced images showing the two components moving round one another. This was the first time that aperture synthesis maps had been produced at optical wavelengths using separate optical elements to collect the light. The closure phase technique they used is a routine tool in radio astronomy but is much more difficult to implement at optical wavelengths.

A 'gentle introduction' to COAST and optical aperture synthesis can be found at http://www.mrao.cam.ac.uk/telescopes/coast/handout.html which includes the first images of Capella as a binary system.

As we come down the meridian we pass the bright hot star Bellatrix at Orion's left shoulder (top right as we look at him). The name is usually translated as 'female warrier' and the star is sometimes known as the 'Amazon Star'. It is one of the hottest blue-white stars with a surface temperature around 21,500 Kelvin and is already a giant. It is not large enough to explode at the end of its life but is predicted to swell into a red super-giant in the next few million years before becoming a massive white dwarf.

Lower down the sky we find the bright star Rigel which marks Orion's left foot (bottom right as we look at him). In mythology Orion was not only a brave and handsome hunter but also extremely arrogant. To punish him the Gods sent a giant scorpion to sting him to death. Orion's dying wish was not to be placed near the scorpion which is why you find Scorpius in the summer sky. Rigel marks the place where the scorpion stung him.

Rigel is a hot bluish-white star about 800 light-years away. It is much more luminous and massive than the Sun and is in the process of dying. It may be burning helium to produce carbon and oxygen in its core and its most likely fate is to explode when the radiation pressure produced by nuclear fusion can no longer balance the gravitational forces that will cause it to collapse.

And finally...

When searching the web for information on stars in Orion most of the results I got for Bellatrix referred to the character in the Harry Potter books. How long before modern mythology completely replaces ancient mythology in the popular imagination?

Clear Skies and Best Wishes

Neil

www.green-witch.com
www.arizonaskyvillage.co.uk
www.astroblast.org.uk