Abstract: The recent launch of the Solar Orbiter (SolO) mission in 2020 has offered new opportunities for the study of the physical processes occurring in the solar atmosphere from a vantage point of observation of about 0.3 AU. The Metis coronagraph aboard the SolO spacecraft is able to take images of the inner corona in visible light and in ultra-violet, in the Ly-alpha line of the neutral hydrogen at 121.6 nm, in a narrow region between 1.7 and 3.1 solar radii from the disk center. Simultaneous observations of the corona in visible and UV light open the possibility to infer velocities of plasma in the corona by adopting the Doppler dimming technique. In this talk we review the first observations collected by Metis, with a special focus on the observations of sungrazing comets, which offer a further way to diagnostic the local properties of the coronal plasma.