SUB-DEGREE ANISOTROPY OBSERVATIONS - GROUND-BASED, BALLOON-BORNE AND SPACE EXPERIMENTS

Extensive, accurate imaging of the Cosmic Background Radiation tempera ture anisotropy at sub-degree angular resolution is widely recognized as one of the most crucial goals for cosmology and astroparticle physi cs in the next decade. We review the scientific case for such measurem ents in relation with sky coverage, attainable sensitivity, confusing foreground radiation components, and experimental strategies. Although ground-based and balloon-borne experiments will provide valuable resu lts, only a well-designed, far-Earth orbit space mission covering a wi de spectral range and a significant part of all the sky will provide d ecisive answers on the mechanism of structure formation.