While driving south on u.S. 101 through south san jose, i suddenly noticed bright shining object ascending. when object flew under a cloud it stopped shining and was a solid black circle. i first thought it must be a small plane reflecting sunlight. there is a small airport, reid-hillview, nearby. when object flew under a cloud it was silhouetted as a solid black circle. it took me a few seconds to realize it wasn't a small plane like i first thought. it was ascending at about a 45 degree angle. when the circle got above the cloud back in the sunlight it started sparkling and shining to where i could not see any of the black circle.