Helium and Hydrogen of the Local Interstellar Mdium Observed in the Vicinity of the Sun

The Sun illuminates the hydrogen and helium atoms of the interstellar medium through which it travels. As a result, the Sun and the whole solar system are imbedded in a glow of the resonance lines of hydrogen (H Lyman alpha; 121.6nm) and helium (58.4nm). From the intensity distribution of the glow in the solar system, the density of H and He in the local interstellar medium (LISM) and the direction of the relative motion between the Sun and the LISM in the vicinity of the Sun are derived. The velocity module and the LISM temperature are more adequately found from a measurement of the Lyman alpha line shape, which is an image of the velocity distribution of H atoms. The result is summarized and together the methods of interpretation and difficulties are dicusssed.