I believe gp's point is that Neutron Stars often have diameters around 10 km (so says Wikipedia anyway ). So, if you're comparing by-diameter and you count neut

I believe gp's point is that Neutron Stars often have diameters around 10 km (so says Wikipedia anyway ). So, if you're comparing by-diameter and you count neutron stars as stars, then a neutron star can absolutely be smaller than a planet. If, on the other hand, the comparison is by-mass, it's a different story. All the best, -HG