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Why is dark matter only found away from Earth?

• dagss 11y ago
  It is certainly found at Earth too. But since you can only interact with it through gravity and the effect is very very small compared to earths gravitation it is not like you can take a picture...
• Jun8 11y ago
  See the answer here (http://physics.stackexchange.com/questions/161267/distribution-and-detection-of-dark-matter http://physics.stackexchange.com/questions/161267/distributi...). Currently we can only detect dark matter indirectly by measuring its gravitational effect. As far as I understand, at small scales (e.g. scale of solar system) it's density is very small.
• dcosson 11y ago
  Statistically, all matter on the scales we're used to is only found away from earth since the universe as a whole (including dark matter) is something like 10^30 times less dense than earth. So if dark matter is found independently of matter* there'd be on the order of 10's of mg of it in the whole earth which would seem impossible to ever measure via gravity. * Probably a huge if, it's just a thought experiment
• antognini 11y ago
  As the other answers have said, there is dark matter expected near the Earth, it's just at a very low density. There have been a number of experiments looking for some signature of weak dark matter interactions near the Earth. One of these, DAMA, has claimed a detection of an annually varying signal which would be consistent with the Earth moving with and against an ambient medium of dark matter over the course of a year. However, no other experiments have been able to verify this detection.