@classmethod
def from_ephem(cls, attractor, ephem, epoch):
    """Create osculating orbit from ephemerides at a given epoch.

        This will assume that the `Ephem` coordinates
        are expressed with respect the given body.

        Parameters
        ----------
        ephem : ~poliastro.ephem.Ephem
            Ephemerides object to use.
        attractor : ~poliastro.bodies.Body
            Body to use as attractor.
        epoch : ~astropy.time.Time
            Epoch to retrieve the osculating orbit at.

        """
    return cls.from_vectors(attractor, *ephem.rv(epoch), epoch, ephem.plane)
