*SPOILER ALERT FOR PRISONER OF AZKABAN* Sirius didn't actually betray the Potters at all, that was Peter Pettigrew.
Sirius Black
Sirius Black
When Lily and James Potter decided to go into hiding using the Fidelius Charm, they were going to use Sirius, James' best friend, as the Secret Keeper, but at the last moment changed to Peter Pettigrew after Sirius suggested that Voldemort would never guess that Peter was the Secret Keeper. Peter, who was secretly a Death Eater, then betrayed the Potters. So the Potters' Secret Keeper was Peter Pettigrew.
Sirius is more of a friend of Harry's. He was best friend to Harry's deceased father, James. James made Sirius Harrys' godfather.
Because harry potters dad, James, had a friend called Sirius and Sirius was a werewolf and to keep Sirius company whilst he was a werewolf he learned to be an animagus.
No. Sirius Black was one of James Potter's best friends. Upon discovering that Voldemort was hunting them, the Potters' went into hiding, naming Sirius as their Secret Keeper, meaning he was the only one to know where they were. At the last moment, Sirius switches from this role with Peter Pettigrew, whom he believed they could trust. Pettigrew betrays the Potters' to Voldemort which results in Voldemort's murdering them, and pins it on Sirius.
Sirius Black was locked away in Azakaban prison.
Anthony
Sirius Black, Remus Lupin, Peter Pettigrew
He is called Sirius Black after the constellation, Sirius. All the people in the Black family are named after constellations. James Potter picked Sirius as his sons godfather because they had been best friends since the age of eleven.
there's a star named Sirius, but no planet .... sorry
Well , no they are not ..Sirius Black is known to be Harrys GODfather with wishes from his dad but there is no blood relation and the weasleys are not related by any way ..:)