The virtual gravity solution is probably the easiest but the article seems to make a meal of it . talk ) 13 : 43, 8 June 2010 ( UTC)
2.
The 2006 observation of a pair of colliding galaxy clusters known as the " Bullet Cluster ", poses a significant challenge for all theories proposing a modified gravity solution to the missing mass problem, including MOND . Astronomers measured the distribution of stellar and gas mass in the clusters using visible and X-ray light, respectively, and in addition mapped the inferred dark matter density using gravitational lensing.