Antony McEwan's monthly digest of HAS happenings.

October 2004 meeting

Tuesday 5th October was a pretty ‘hot’ meeting. Observing season is well and truly upon us now, and several good observing opportunities coming our way were discussed. Late nights loom, but if your favourite star is the mysterious and mythical ‘Sun’ (big bright disc sometimes seen in daytime sky), then our main event was where you should have been, as Dr Lyndsay Fletcher gave a searing talk detailing the recent achievements of the RHESSI solar observation project. To start us off, Pauline presented this month’s notices.

• Dr. Mark Sims Elgin Talk Dr. Mark Sims visited Elgin Academy on September 25th to give a talk about the Beagle 2 mission, why it failed, and the future of Mars exploration. There was a very large turnout to hear him speak, including members of Sigma and the Aberdeen and District Astronomical Society. Ultimately the team of scientists still don’t know for sure what happened, as they have calculated a total of about 150 things that could have gone wrong and narrowed it down to their top dozen or so most likely probabilities. These even include the possibility of a perfect landing with just a broken connection disabling the transmitter. Favourite, though, is the idea that the atmospheric conditions were not exactly as predicted and this may have caused the parachutes to deploytoo late, causing the spacecraft to impact on the surface rather too quickly. Dr. Sims and his colleagues are keen to put the lessons learned in Beagle 2’s failure to use on another attempt to land a probe on Mars, and I’m sure we all wish them well with that. Thanks were extended to Geoff King and Andy Ferguson for use of their presentation equipment, and to the Committee, particularly Trina, Arthur and Colin; to Steven, and everyone else who helped in this event, including the many who contributed raffle prizes. Dr. Sims has agreed to become an honorary HAS member and will be keeping in touch with us. You can read the full 288 page report on the mission’s failure (or a shorter version) at the Beagle 2 website.

• Observation Nights Yes, it’s that time of year again. Time to get out the thermal undies and head up to Culloden at the weekends. Observing sessions will take place on Friday and Saturday nights throughout the winter months. Octobers sessions (so far) are:

Friday 8th October……..Pauline

Saturday 9th October…..Trina

Friday 15th October…….Maarten

Saturday 16th October….Rob

The sessions will start at 8pm and continue until 11pm. For more details please use the above contact numbers. If you are working towards completing your Lunar 100 sheet and wish to use the observatory’s large reflector on a moonlit night, remember to contact a member of the Committee to see if it is possible.

• Total Lunar Eclipse Mention was made of the forthcoming total lunar eclipse on the morning of Thurs 28th. Please see ‘Eyes On The Skies’ section below for more details. Please note that the times given in the recent Inverness Courier article were stated in Universal Time, not British Summer Time. To convert them to BST just add one hour to the Universal Time.

• HAS-WEAR A sample sweatshirt has been received from one of the companies we are considering using to produce clothing bearing the Highlands Astronomical Society logo. The logo was slightly oval instead of being circular, and the font used for the text a little difficult to read, so we are still researching. It will definitely be one of the two local firms in Elgin and Nairn, thatwill beused. A catalogue is available, and if you are interested in ordering items, please bring monies with you to the next meeting. Mugs with the HAS logo will also be available if we decide to use the Elgin firm.

Eyes On The Skies October’s constellation of the month was Cassiopeia, and this should be a fine part of the sky to explore in the coming weeks of dark nights. The Milky Way passes right through Cassiopeia and litters the area with many beautiful open clusters. Some are so open, in fact, that you may be better viewing them with binoculars or a small wide-field telescope.

Those hunting for brighter targets may be happier with the total lunar eclipse which takes place in the early hours of Thursday 28th October. Clear skies permitting, we hope to see the gradual encroachment of the Earth’s shadow across the full Moon, and should see some striking colour changes take place. The start of the umbral (most visually impressive) phase is 02:14 BST. The whole Moon should be engulfed in the Earth’s shadow at 03:23, and this phase will end at 04:44. This will be visible from all over the Highlands, but if you’d like some company while watching the event, feel free to come up to the Observatory at Culloden at 3am. If the weather is cloudy or rainy there is little chance of there being any observing team members at Culloden. Please use your own judgement in this case, as phone calls in the wee small hours may not be appreciated by non-stargazey family members!

The easiest of the current batch of comets to catch should be Comet 2001Q4 NEAT, which is fading to 10th magnitude as it moves through Ursa Minor. A Finder Chart is available here ,courtesy of the nice folks at NASA JPL.

By mid-month Saturn will be rising shortly after 10pm and will be in a very good viewing position after midnight. This is a great time to look as the rings are wide open, and, as you peer into your eyepiece, you can imagine the adventurous Cassini probe circling the planet and gathering its latest batch of scientific data. No, you won’t see it with your ‘scope, not even the 12” Dobs, Maarten.

The Main Event

This month’s talk was ‘Recent Advances with RHESSI’ and was given by Dr Lyndsay Fletcher. Dr Fletcher has a PhD in solar physics and has followed a career based on solar study, including research at the European Space Agency and work on the SOHO, TRACE and Yohkoh solar missions.

The RHESSI satellite (Ramaty High Energy Solar Spectroscopic Imager) is one of NASA’s successful ‘Small Explorer Missions’ and is designed to continuously monitor the Sun using a complex array of optics. The imager was named posthumously after Dr Reuven Ramaty, a pioneer in the fields of solar physics, gamma-ray astronomy, nuclear astrophysics, and cosmic rays. He was also a founder member of the HESSI production team.

During the fascinating and illuminating talk we were shown movies made from images taken by the TRACE solar imager. Aside from the scientific data that these images provide, the movies were just breathtaking, showing the incredible power and activity of our parent star. We were then shown movies that superimposed the RHESSI image onto the TRACE image. The RHESSI image is much more basic in appearance, but is able to provide scientists with important data regarding high energy X-ray and Gamma ray activity.

Dr Fletcher explained that the processes of coronal mass ejection, solar flares and other eruptions are all interconnected with the very complex system of magnetic fields the sun exhibits. These fields affect the flow of charged particles through the sun, resulting in some particles moving at nearly the speed of light. The corresponding amounts of energy released by eruptions with such fast particles are awesome, and apparently one coronal mass ejection could provide enough energy to power the whole United States of America for about 400 years.

Dr Fletcher also stated that the study of the sun is a long and slow process. Discoveries are only made after long periods of analysing images and data, and there are many mysteries to be solved which will take a long time. With the enthusiasm and dedication that Dr Fletcher exhibited in her talk, I’m sure that those mysteries are well on their way to being solved.

More information on RHESSI can be obtained at the project’s website.