Various high-resolution or high-frame-rate image sensors are used in star trackers to improve attitude accuracy and attitude update rate. However, the use of these high-performance image sensors has generated a new problem. The speed requirement of star detection and centroid calculation (SDCC) exceeds the capability of existing SDCC methods. Therefore, this paper presents a new real-time super-block-based SDCC method to resolve such a problem. In contrast to the traditional SDCC methods, the proposed method process the star images four by four and considering the continuous eight-connected pixels in the two lines as a super-block. The proposed method exhibits a speed that is four times faster than the previous SDCC methods. Thus, the performance limitation caused by the inadequacies of SDCC speed is solved. Experimental results indicate that the proposed method is correct and effective.