Star polymers are prototype systems both for tethered chains as well as for branched polymers. In this study we present a thorough investigation of the single star form factors in dilute solutions spanning a range of functionalities from 8 to 128. Using the zero average contrast method the form factor determination was also extended into the semidilute regime. As a consequence of their very inhomogeneous monomer density distribution star polymers exhibit osmotic repulsion leading to ordering phenomena in the neighborhood of the overlap concentration. We present a detailed investigation of such ordering phenomena in star polymer solutions with varying functionality and molecular weight. In all cases we observe an interparticle structure factor which is most pronounced at the overlap concentration Φ*. The ordering tendency increases with increasing functionality. These results are compared with current theoretical predictions