We show a laboratory experiment in which students can learn the use of interferometry as a valuable
tool in astronomy. We detail experiments based on the use of the classic Michelson stellar
interferometer able to reproduce the size of single stars and to characterize double star systems.
Stellar sources, single and double, are reproduced by a laser light emerging from the circular end
faces of one or two step-index polymer optical fibres. Light coming from the fibre end faces passes
through two identical pinholes located on a lid covering the objective of a small telescope, thus
producing interference fringes. The measurement of the fringe visibilities allows us to estimate
both the diameters of the simulated stars and the separation between them, with errors lower than
18% for a range of light sources that can recreate the apparent size of the outer Solar System
planets Uranus and Neptune and the binary properties of the Alpha Centauri system. The exercises
here described illu…