wa2ise@cbnewsb.cb.att.com (robert.f.casey) (06/17/91)
This thought crosses my mind on the topic of dark matter: There can't be much of any sort that we are not familiar with in the solar system. Or else the laws of Gravitation that Newton discovered would be confused. If the solar system was imbedded in a sea of unusual dark matter, calculations on the interactions between planets wouldn't work out right. Maybe further out there is some dark matter to explain the deviations of Neptune that prompted the search that found Pluto. There can't be much in the inner solar system, or else our space probes, satellites and moons would travel on paths that wern't correctly predicted. Any of you rocket scientists in the know have comments?
pfennige@uni2a.unige.ch (06/17/91)
In article <10705@suned1.Nswses.Navy.MIL>, lev@slced1.nswses.navy.mil (Lloyd E Vancil) writes: ... > And I was wondering, why cant "dark matter" be planets, rocks, comets, etc etc? Heavy atomic elements heavier than He are thought to have been synthesized mainly by massive stars, because first these stars evolve in a short time (~10^7 y), and second they eject most of their processed mass back into the interstellar medium (such as supernovae). So the possibility of rocky planets such as the earth depends on the previous evolution of massive stars. Now, when stars form from a gas cloud, most of the mass is going into low mass stars, which evolve very slowly (>10^9 y). In conclusion it seems very difficult to make dark matter by mainly heavy elements, because their processing needs to lock even more mass in low mass stars, for a time as long or longer than the age of the Galaxy. Daniel Pfenniger