def METHOD_NAME(theta, phi, theta0, phi0):
    """ Find the phase angle of the point closest to the given point on the great circle. 
    Arguments:
        theta: [float] Inclination of the point under consideration (radians).
        phi: [float] Nodal angle of the point (radians).
        theta0: [float] Inclination of the great circle (radians).
        phi0: [float] Nodal angle of the great circle (radians).
    Return:
        [float] Phase angle on the great circle of the point under consideration (radians).
    """
    def _pointDist(x):
        """ Calculates the Cartesian distance from a point defined in polar coordinates, and a point on
            a great circle. """
        # Convert the pick to Cartesian coordinates
        point = polarToCartesian(phi, theta)
        # Get the point on the great circle
        circle = greatCircle(x, theta0, phi0)
        # Return the distance from the pick to the great circle
        return np.sqrt((point[0] - circle[0])**2 + (point[1] - circle[1])**2 + (point[2] - circle[2])**2)
    # Find the phase angle on the great circle which corresponds to the pick
    res = scipy.optimize.minimize(_pointDist, 0)
    return res.x