  The current attempt is aimed to honor the first centennial of Johannes
Diderik van der Waals (VDW) awarding Nobel Prize in Physics. The VDW theory of
ordinary fluids is reviewed in the first part of the paper, where special
effort is devoted to the equation of state and the law of corresponding states.
In addition, a few mathematical features involving properties of cubic
equations are discussed, for appreciating the intrinsic beauty of the VDW
theory. A theory of astrophysical fluids is shortly reviewed in the second part
of the paper, grounding on the tensor virial theorem for two-component systems,
and an equation of state is formulated with a convenient choice of reduced
variables. Additional effort is devoted to particular choices of density
profiles, namely a simple guidance case and two cases of astrophysical
interest. The related macroisothermal curves are found to be qualitatively
similar to VDW isothermal curves below the critical threshold and, for
sufficiently steep density profiles, a critical macroisothermal curve exists,
with a single horizontal inflexion point. Under the working hypothesis of a
phase transition (assumed to be gas-stars) for astrophysical fluids, similar to
the vapour-liquid phase transition in ordinary fluids, the location of gas
clouds, stellar systems, galaxies, cluster of galaxies, on the plane scanned by
reduced variables, is tentatively assigned. A brief discussion shows how van
der Waals' two great discoveries, namely a gas equation of state where tidal
interactions between molecules are taken into account, and the law of
corresponding states, related to microcosmos, find a counterpart with regard to
macrocosmos. In conclusion, after more than a century since the awarding of the
Nobel Prize in Physics, van der Waals' ideas are still valid and helpful to day
for a full understanding of the universe.
