Of smaller size but which remains imposing and of different design, let us quote also the radio-telescope of Nançay of the CNRS installed in the Cher in France put in …

It has been known since the discovery of Heinrich Hertz in 1887 that radio waves are of the same nature as light waves. In particular they propagate in a vacuum …

While the eye is sensitive only to the light perceived instantly, the silver medium (photo plate and films) that was still used until the 1980s can record the light received …

It is enough to have spent a few seconds on the eyepiece of a so-called azimuthal instrument, mounted on a tripod, to be aware of the sidereal movement which causes …

Around the world, about thirty observatories have dedicated at least one telescope to the study of the Sun. Given the atmospheric turbulence, it is almost impossible to use instruments over …

Since the manufacture of the 5 m diameter mirror of the Mount Palomar Observatory in 1939, because of their gross mass exceeding 40 tons, the mirrors of the large telescopes …