One U.S. communications satellite has collided with one defunct Russian satellite in space, NASA said Wednesday.

The first such collision in space occurred Tuesday nearly 805 km over Siberia, NASA spokesman Kelly Humphries said.

A pair of massive debris clouds was produced after the crash, the spokesman said, adding that the magnitude of the accident was still unknown.

Pope Benedict XVI has told Jewish leaders that any denial of the Holocaust is intolerable and unacceptable, especially if a priest does it.

Benedict said during a meeting on Thursday at the Vatican with about 60 American Jewish leaders that he is preparing to visit Israel.

The audience was scheduled after Benedict lifted the excommunication of a traditionalist bishop who denied the Holocaust, sparking outrage among Catholics and Jews alike.  

Physical exercise triggers brain activity that may help reduce craving for cigarettes.

For the first time, researchers used functional Magnetic Resonance Imaging (fMRI) to investigate how the brain processes images of cigarettes after exercise.

The study backs up previous studies, which have shown that just one short burst of moderate exercise can significantly reduce smokers’ nicotine cravings.

Kate Janse Van Rensburg, doctoral student at the University of Exeter, who co-authored the paper, said: “Our findings add to a growing body of evidence suggesting that exercise can help people give up smoking”.