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Saturday, November 27, 2004
Quarter Million Year Canon of Solar System Transits
Last May I decided to see if the long-term evolution of planetary orbits in the Solar System ever resulted in a simultaneous transit of Mercury and Venus visible from Earth in the distant past or future (I chose a period of ±125,000 years for the investigation). Little did I know at the time that Jean Meeus was working on the same problem, and beat me to the solution, publishing the July 69163 simultaneous transit in the June 2004 issue of The Journal of the British Astronomical Association. But all was not lost, since my transit finder, based on Steve Moshier's DE118i-2 numerical integrator, was producing a list of all planetary transits (excluding grazes and short events which start and end within one integration step of 1/100 day [14.4 minutes]), plus barycentre excursions. Suitably post-processed by a camel of Perl programs, the results were assembled into a comprehensive catalogue of transits, which is now posted. All of the software used to produce the canon is available for downloading, as is the canon itself in CSV format. Computation of the list of transits took two months on my 1 GHz "laptop", with the backward integration running for a month in parallel on another 400 MHz machine, then transferred back to the faster laptop after it completed the forward integration. In any project like this, one always worries about whether the answers obtained are, you know, right, so I spent a lot of time on both internal consistency checks of the results and comparing them to other published investigations of historical and future transits, described in a section near the end of the document.Posted at
15:45
Reading List: Financial Reckoning Day
- Bonner, William with Addison Wiggin. Financial Reckoning Day. Hoboken, NJ: John Wiley & Sons, 2003. ISBN 0-471-44973-3.
- William Bonner's Daily Reckoning newsletter was, along with a few others like Downside, a voice of sanity in the bubble markets of the turn of millennium. I've always found that the best investment analysis looks well beyond the markets to the historical, social, political, moral, technological, and demographic trends which market action ultimately reflects. Bonner and Wiggin provide a global, multi-century tour d'horizon here, and make a convincing case that the boom, bust, and decade-plus "soft depression" which Japan suffered from the 1990s to the present is the prototype of what's in store for the U.S. as the inevitable de-leveraging of the mountain of corporate and consumer debt on which the recent boom was built occurs, with the difference that Japan has the advantage of a high savings rate and large trade surplus, while the U.S. saves nothing and runs enormous trade deficits. The analysis of how Alan Greenspan's evolution from supreme goldbug in Ayn Rand's inner circle to maestro of paper money is completely consistent with his youthful belief in Objectivism is simply delightful. The authors readily admit that markets can do anything, but believe that in the long run, markets generally do what they "ought to", and suggest an investment strategy for the next decade on that basis.
Posted at
15:10