Changes

==Explanations==

==Explanations==

There are many possible explanations for the effect, including a failure of general relativity at these speeds or distances.   

There are many possible explanations for the effect.

 

* The anomalous acceleration could be due to the spacecraft venting energy in certain directions.<ref>http://www.symmetrymagazine.org/breaking/2008/04/13/pioneer-spacecraft-a-step-closer-to-being-boring/</ref>.

* The [[theory of general relativity]] and the [[law of universal gravitation]] could be wrong; the gravitational force could be slightly stronger than predicted.  In this context, it is important to note that other spacecraft flying by celestial bodies have also experienced anomalous gravitational effects.

* There could be gravitational forces from other celestial bodies that have not been taken into account.  Dr. [[Russell Humphreys]] has explained the Pioneer Anomaly as part of [[Starlight_problem#Humphreys.27_model|his new cosmology]], as the pull from the center of mass of the universe.

{{Relativity}}

{{Relativity}}