From: alain245@videotron.ca   
      
   On Aug/12/2020 at 19:43, JF Mezei wrote :   
   > On 2020-08-12 15:32, Snidely wrote:   
   >>> Comet Swift-Tuttle last reached perihelion – closest point to the sun   
   – in   
   >>> December 1992 and will do so next in July 2126.   
   >>>    
   >   
   > Thanks was unaware of the link between the two.   
   >   
   > I recall meteor showers in august since I was a kid. Does this mean that   
   > prior to 1992, the showers I saw were leftovers from Swift Tuttle's 1858   
   > crossing of Earth's orbital path leaving a trail of debris that is so   
   > longthat we get some every time we pass through that path in August for   
   > 134 years until comet passes again?   
      
   No, the showers that you saw were leftovers from Swift-Tuttle's passing   
   long before 1858. The debris Swift-Tuttle left in 1858 are still near   
   the comet, so they weren't hitting Earth in 1989 or in 1995 when   
   Swift-Tuttle was far from Earth. The debris Swift-Tuttle has shed in say   
   188 can be quite far from the comet by now and can hit Earth many years   
   before or after the comet passes close to Earth.   
      
   > The comet has no precession and always passes through the exact same   
   > spot at its perigee, a spot which corresponds to where Earth passes   
   > roughly august 11 ?   
      
   Swift-Tuttle has a period of about 133 years. Its precession will change   
   its orbit by a very small amount every 133 years. By the time precession   
   will have a significant effect, the comet will probably be dead.   
      
   > is it correct to state that the debris left by Swift Tuttle rekain in   
   > the same orbit as the comet, with same energy/speed/altitude form sun   
   > and same eccentricity?  Over time, would debris tenmd to clump together   
   > due to each rock's gravity and all of then traveling at same speed/vector ?   
      
   They follow orbital paths very close to the path of the comet, but not   
   exactly the same. We are talking about debris about the size of grains   
   of sand, their gravity is negligible, so they won't clump together. With   
   time, they tend to spread out, that is why we get the meteor showers   
   even on years were the comet is far away.   
      
      
   Alain Fournier   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)