Meteors – Tiny Remind Members of the Forthcoming Back Ured Possession
Total Page：16
File Type：pdf, Size：1020Kb
Meetings Ordinary Meeting and Christmas Lecture, 2004 December 18 held at The English Heritage Lecture Theatre, 23 Savile Row, Piccadilly, London W1 Tom Boles, President stopped counting at 200, though there were to Sir Patrick for his very great effort to travel Ron Johnson, Nick Hewitt and Nick doubtless many more. The first, on the sub- up from his Selsey home to attend the after- James, Secretaries ject of lunar craters, was written at a mere noon’s meeting. fourteen years of age, and though it was so Mr Boles then introduced the afternoon’s The President opened the third Ordinary long ago, the President supposed a first pa- first speaker, Professor David Hughes, who Meeting of the 115th session, and invited per was always one to be remembered. Per- would deliver the 2004 Christmas Lecture. Dr Nick Hewitt to read the minutes of the haps Sir Patrick’s greatest contribution of all Prof Hughes presently headed a planetary previous OM, which were duly approved. was through the interface he provided be- sciences group at the University of Sheffield Mr Boles said that the names of 25 candi- tween the Association and the media. His specialising in cometary research, and the dates for election to membership would be popularisation of astronomy had brought in President remarked that a casual search for displayed in the Association’s library, and numerous young people, and Mr Boles re- his publications had brought up no less than the 24 candidates proposed at the previous marked that it was a common observation 320 papers bearing his name. Given his ac- meeting, finding the approval of the audi- by many now-professional astronomers that tive interest in the Rosetta mission, Mr Boles ence, were declared elected. The President they had first been inspired into the field by supposed he would be kept busy until at invited any new members to introduce them- Sir Patrick’s work. least 2014, waiting for the return of data. selves to him later. Mr Nick James, papers On behalf of the Officers, Council and secretary, said that two papers had been ac- Members of the Association, in recognition cepted for Journal publication: of all his many contributions, the President V973 Cygni − an overlooked semi-regular offered Sir Patrick his warmest congratula- variable, by John Howarth tions on his 70th anniversary. In view of his Comets, and their Chromospheric darkenings around active lifelong passion for the observation of the areas, by Eric Strach Moon and planets, no gift seemed a more exploration by The next meeting would be on 2005 Janu- fitting memento than a handcrafted brass or- ary 26 at the Geological Society, Burling- rery, which, to great applause, Mr Boles pre- spacecraft ton House, when the main speaker would sented to Sir Patrick. be Dr David Boyd, speaking on Clocking a Rising to his feet, with apologies that his Prof Hughes first wished to thank the Asso- Spinning White Dwarf, followed by contri- mobility was not what it once was, Sir ciation for inviting him to deliver the Christ- butions from Martin Taylor, Peter Wise and Patrick thanked all for this reception: the mas Lecture. He recalled that he had started Nick James. The President also wished to orrery would, he assured members, be a treas- his career with an interest in meteors – tiny remind members of the forthcoming Back ured possession. He remembered well the dust grains broken from the surface of com- to Basics course, to be held in Chichester day, 70 years before, when he had, as an ets, producing streaks of light across the sky on January 29. 11½-year-old, had to walk forward to shake upon impact with the atmosphere. With time Before proceeding to the afternoon’s talks, hands with the then President of the Asso- his interests had moved from the dust grains Mr Boles remarked that the meeting was tak- ciation, and incidentally also then Astrono- to the comets themselves, but they illustrated ing place in the month of a significant his- mer Royal, Sir Harold Spencer Jones. Remi- a central theme of the talk to come: comets torical anniversary, for at the meeting of 1934 niscing of some of the past members he had were dying objects, always getting smaller. October 28, seventy years previously, a known over those 70 years, and some of the The first part of the talk would be a general bright youth, 11½ years of age, had been lighter moments he had shared with them, he introduction to comets, followed by a dis- elected a member of the Association. At the remarked that the Association remained un- cussion of space missions which had ex- time, this must have seemed no special occa- changed. Astronomy had moved on, but the plored them, winding up with a discussion sion, but with time that bright youth was to Association had always moved with it. He of unanswered questions. The speaker re- work up through the ranks of the Associa- always thought it important to re- tion, and to become the author of many books member that the Association was, and a TV presenter. He would become fa- above all else, the observers, and that mous around the globe. The youth was, of through their work, it had played a course, Sir Patrick Moore, and the President tremendous part in astronomy, both scarcely had to inform members of his pres- in the UK and abroad, building up a ence at the Meeting, for few could have failed great deal of interest in the field. He to notice the applause which had erupted described the BAA as a cornerstone some minutes earlier, upon his entry to the to astronomy, and he greatly regret- theatre. ted that it seemed unlikely to him Almost exactly 20 years ago, Sir Patrick that he would be able to attend any had held the Presidency of the Association; further London meetings. Finally, Sir he had also at various times held the posi- Patrick wished to thank all for the tions of Director of the Lunar and Venus kind invitation to such a reception in Sections. In total, he had been a member of recognition of his anniversary. His Council for no less than 40 years. He had speech was followed by prolonged Sir Patrick Moore (left) with Martin Mobberley at been a prolific writer of papers for the Jour- and emotional applause, after which the BAA Christmas meeting. (Photo courtesy Martin nal: the President had to confess to having the President returned his own thanks Mobberley) J. Br. Astron. Assoc. 115, 5, 2005 287 Meetings marked that there was no shortage of these: no one knew quite how many. Furthermore, orbits of many comets, each taking several he had thought of no less than fourteen em- because they spent time both far from the weeks. It was through this work that his sus- barrassingly simple questions which science Earth, and rather closer to it, the risk of one picions had been aroused upon noticing had not yet succeeded in answering. colliding with our planet was one that had to amongst his catalogue three comets, in 1682, Observers had long been familiar with the be monitored. Historically, it seemed prob- 1607 and 1531, each with a near-identical or- fact that comets were surrounded by a coma, able that much of the water in the oceans had bit, and each separated by around 76 years. which had led to the idea that they comprised arrived in the impacts of comets. The comet in question was the one now a sublimating dirty snowball nucleus, a sug- Comets were among the most beautiful of known as Halley’s Comet, and it had been the gestion traceable back to Newtonian origin, the naked eye offerings of the sky, and the first time that anyone had proposed that they though in modern times it had first come to speaker showed a few of his favourite im- might return periodically. widespread acceptance through the work of ages. These included an exceptional image of The speaker remarked that Hevelius had Fred Whipple. Another familiar fact was that Halley, with, in the foreground, a burning thought that comets were made of material comets evolved: as they approached the Sun, dust grain from another comet in the form of ejected from the surfaces of planets, spun the rate at which material was lost changed a Quadrantid meteor. The speaker also off rather like the hurling of a discus. The rapidly. Using the familiar example of Halley’s showed an artistic photograph of Comet curvature of the subsequent trajectory would Comet, the speaker quantified this: at a dis- Bennett from Switzerland, just above the be determined by the speed of the ejection. tance of 3AU from the Sun, the nucleus was Moon-illuminated Jungfrau. Prof Hughes By contrast, the opposite was now under- thought to lose an average of one molecule remarked that this particular comet appeared stood to be true: comets often added new per square centimetre per second, yet at peri- to have fragmented in 1974, and that this material to planets. It was widely thought helion, 0.5AU from the Sun, it was thought was not well understood. Little was known that Jupiter and Saturn both harboured rocky to lose 11,000 molecules/cm2/s. The speaker about the mass, composition, or mechanical nuclei of around 10−20 Earth masses, each remarked that as well as ice, this also included strength of cometary nuclei, and so in turn, composed mostly of cometary material. rocky debris, the dust from which (in the case little was known about what was needed to The process of this accretion could be il- of Halley) gave rise to both the Orionid and break them apart.