The prolate solar chromosphere

We present a comparative analysis of the chromospheric solar limb prolateness, using strictly simultaneous H\_alpha ground-based observations and Heriptsize$\{$II$\}$ space-based observations. The typical prolateness is found to be Delta D/D=5.5*E(-3) in Heriptsize$\{$II$\}$ and 1.2*E(-3) in H\_alpha . The first measurements in the 30.4 nm Heriptsize$\{$II$\}$ line over a period of two years, as well as coronal data, are discussed to explore further the origin of the prolateness and its possible consequences.