VY Canis Majoris (VY CMa). University of Minnesota professor Roberta M. Humphreys estimates the radius of VY CMa at 1800 to 2100 solar radii.

"VY Canis Majoris (VY CMa) is a red hypergiant star located in the constellation Canis Major. It is possibly the largest known star and also one of the most luminous known. It is located about 1.5 kiloparsecs (4,900 ly) away from Earth." "University of Minnesota professor Roberta M. Humphreys estimates the radius of VY CMa at 1800 to 2100 solar radii. To illustrate, if our Sun were replaced with VY Canis Majoris, its surface might extend to the orbit of Saturn. Assuming the upper size limit of 2100 solar radii, light would take more than 8 hours to travel around the star's circumference, as opposed to 14.5 seconds for the sun. It would take over 7,000,000,000,000,000 (7 Quadrillion) earths to fill Canis Majoris." Source and further information: http://en.wikipedia.org/wiki/VY_Canis_Majoris Further information: http://en.wikipedia.org/wiki/List_of_largest_known_stars http://www.techdo.com/images/largest-know-star.htm Universe size comparison http://www.youtube.com/watch?v=EDNEV9EW06g The biggest star known to man http://www.youtube.com/watch?v=I34FNr_peUk Our Size in the Universe http://www.youtube.com/watch?v=WcZkAZebK1U

Here you go VY canis majoris

Rosie O'Donnell? I dunno about "star", but she must go about 300, no? ;-)