According to Newton's law, the attraction exerted by the Sun on the Moon is greater than twice the attraction exerted by the Earth on its satellite, whatever the Moon's position during its motion. Nevertheless, the Moon's orbital plane around the Earth forms a 5.13 degree angle with the ecliptic's plane. The texts of astronomy I could so far access do either omit explaining this fact or clearly admit that current perturbation analysis does not provide any complete and clear explanation on the topic. It seems to be one of the anomalies detected within the solar system. Somebody might remark that it's a "neglible" aspect, whereas the fact seems to imply that the Moon orbits the Earth irrespective of the solar attraction. In this connection, there is also to consider that the centre of mass of the Earth-Moon system does also orbit the Sun out of the ecliptic, and not according to any plane curve as instead required by the dynamics of central motions. My question: is there any updated study relevant to the issue?