Planar zeros are an interesting feature of certain scattering amplitudes with one or more gauge bosons radiated, consisting in the vanishing of the amplitude for configurations where all momenta lie on a single plane. In this talk I shall study these planar zeros in various field theories at tree-level. In the case of theories with gauge invariance, the zeros are determined by the vanishing of a homogeneous polynomial in the stereographic coordinates determining the direction of flight of the particles involved. This projective property is absent in pure scalar theories. In gravitational theories, on the other hand, amplitudes vanish whenever the scattering is planar. String theory corrections to the field theory amplitudes spoil the projective nature of gauge planar zeros, as well as the vanishing of gravitational planar amplitudes.