What is the Mojo layer inside the earth? How far down is it inside the earth?
The Moho, for Mohovorovicic Discontinuity, is the boundary between the crust and the upper mantle. On average it's about 35 km deep under the continents, 5-10 km under the oceans.
The Moho was discovered, via seismic wave measurements, by Croatian scientist Andrija Mohorovicic in 1909.
See below for a contour map of the depth of the Moho.
The map is linked to a Wikipedia article.