A partially occulting MACHO-microlensing event in the Twin Quasar Q0957+561

A doubly-peaked quasar microlensing event in the lensed Twin Quasar Q0957+561 A,B (Colley and Schild 2003) is analysed within several lensing models. In the most realistic model a lens resolves in image B the ellipse shaped, bright inner rim of the quasar's accretion disk, intersecting it twice. This lens weighs 0.5 Earth mass and is located inside the Galaxy, at 3 kpc distance. During the passing, it partially occults the source, which allows to describe it as a primordial gas cloud of 1.4 Solar radius and 17 K temperature, in accordance with the theory of Gravitational Hydrodynamics. Lensing by such objects against the Magellanic Clouds and Galactic centre will also lead to occultation dips.