Dwarf spheroidal galaxies are the smallest and most tenous galaxies in the Universe, yet they might hold key information about the validity of lambda CDM. Recently, larger surveys have found a large number of such small galaxies around the Milky Way. Earlier, the low number of known dwarf spheroidal galaxies was a problem since lambda CDM predicted substantially larger numbers of such galaxies. I will briefly review this background and then present recent results for a few of the newly found dwarf spheroidal galaxies. In particular I will discuss the mass of Hercules, the metallicity and elemental abundances of Boötes I and the strange object in UMa II and connect our results to the broader picture of the role dwarf spheroidal galaxies play in the formation and evolution of large galaxies, like the Milky Way. (Host: Kambiz Fathi)
