Satgen446 Leonids Meteor Buildup by GM4IHJ (BID SGEN446) 11 Oct 97 Each succeeding year for the past few years, the zenith hourly rate of the November 17th Leonids meteor shower, has increased steadily. We are not due for the 33 year "Special" Leonids cyclic maximum until 1998 or 1999, but we should get a strong shower this year, even if it does not match up to the famous Leonids of old ( 1866, 1900 and 1996) which caused song writers to write " Stars fell on Alabama". Comet Temple-Tuttle is the progenitor of the Leonids, and the comet is approaching the Sun now, and should be visible via small telescopes next year. This year the Earth is due to pass through the plane of the comets orbit at 1240 ut on the 17th of November next. But meteor watcher may recall that last year a very good peak occured about 90 minutes before calculated passage throught the orbit plane. As the peak occurs in daylight for them, Europeans will hopefully have a good radio shower but will see almost nothing of the visual shower. By contrast, in the western USA it will be early morning for both the predicted plane passage and any earlier repeat of last years " 90 minutes early event". So hopefully Californians will hear a good radio shower and see an excellent visual meteor display. Fortunately all these meteors should be small ones. Unlike the shower of sizeable collision debris recorded by the recent Clementine US military Lunar mapper which imaged the Moon so spectacularly and found large relatively young craters on the Moon's farside. Subsequent examination of Clementine records suggests these craters are young by Lunar standards, being about 545 million years old. A long way in the past for us but much more recent than any of the other lunar craters though they are dated by coincidence to the time when life on earth suddenly exploded into generation of many of the basic shapes and forms of life we see around us now. For it is very probable that what hit the Moon was accompanied by a lot of material which hit the Earth. But here on earth, weathering and erosion effects have wiped out most if not all of the traces of craters from that period. Though satellite viewers who live in North America or indeed even in Scotland , can see one crater regularly on Wefax pictures of Quebec Canada. Where, not even the glaciers of recent ice ages have wiped out the 61 Km "eye" of the circa 200 million year old Manicouagan crater at 51.5N 68.6W, just north of the Gulf of St Lawrence. Even bigger , and a lot older is the half crater in the east side of Hudsons Bay , often seen on the same pictures as Manicouagan. The Hudsons Bay crater has lost its western wall but still retains the central islands which like the peaks in the middle of lunar craters , are a feature of very big craters , where the centre rebounds to form a local mountain. Unfortunately for comparison with Clementines Lunar farside 545 million year old craters , the Hudsons Bay one is reckoned to be a minimum of 600 million, maximum of 1000 million years old. So it too is unlikely to have any connection with the Clementine craters.