A mysterious anomaly in space seen on two NASA probes that has caused scientists to question the laws of physics may  just be a trick of the light, a new study suggests.

The study may answer questions dating back more than a decade, when anomalies were seen in the trajectories of the identical Pioneer 10 and 11 deep space probes as they hurtled out of the solar system. Both seemed to experience a tiny, mysterious amount of acceleration that seemed to hold them back as they headed away from the sun.