Any online certificate courses from reputed universities?

Do any of the big universities (Stanford, MIT, Oxford, etc.) offer online courses that we can pursue as a part-time study?

I am interested in courses that offer a formal certificate from the university.

I have wide interests – ranging from astronomy to music to business management – and would like to pursue these interests further. I am also wondering it would be worthwhile the effort if one can also keep a objective goal of achieving a certification from a much recognized authority. I am looking for a part-time, online course because I cannot take a break from work or travel to another country for this.

Any advice is appreciated. Thanks!