A spacecraft with a yaw steering system performing yaw steering. The yaw steering includes steering the spacecraft to have a yaw angle (.psi.) for all sun elevation angles (.beta.) in accordance with a yaw steering guidance law that provides a yaw steering motion about a yaw axis which is smooth for all sun elevation angles (.beta.). At least part of the guidance law comprises a smoothing function (f), which is a function of an orbital position parameter (.eta.) of the spacecraft, the smoothing function (f) smoothing the yaw steering motion for values of the orbital position parameter (.eta.) where high rotational rates {dot over (.psi.)} or high rotational accelerations {umlaut over (.psi.)} would occur without the smoothing function (f).