That is incorrect. What you describe is a dipolar oscillation. The simplest gravitational waves woudl have a quadrupole moment: stretch in one direction while c

That is incorrect. What you describe is a dipolar oscillation. The simplest gravitational waves woudl have a quadrupole moment: stretch in one direction while contracting in the direction perpendicular to it. Have a look at https://en.wikipedia.org/wiki/Gravitational_wave https://en.wikipedia.org/wiki/Gravitational_wave where there is an animation illustrating the simplest case.