Cosmic Distances: Current Odds and Future Perspectives

We discuss recent theoretical and empirical results concerning cosmic distances and discuss the problems affecting the Cepheid and the RR Lyrae distance scales. In particular, we outline the key role that first overtone Cepheids can play to improve the accuracy of distance determinations to nearby galaxies. We also address the positive features of the K-band Period-Luminosity-Metallicity (PLZ_K) relation of RR Lyrae stars when compared to the M_V vs [Fe/H] relation. Moreover, we discuss the impact that accurate multiband data in external galaxies can have on the evolutionary properties of intermediate and low-mass stars. Finally, we introduce possible avenues of future research in stellar astrophysics.