Planet solar wind around itself called the magnetosphere, which the wind cannot penetrate. The magnetosphere can be much larger than the planet itself. In contrast, non-magnetized planets have only small magnetospheres induced by interaction of the ionosphere with the solar wind, which cannot effectively protect the planet. Of the eight planets in the Solar System, only Venus and Mars lack such a magnetic field. In addition, the moon of Jupiter Ganymede also has one. Of the magnetized planets the magnetic field of Mercury is the weakest, and is barely able to deflect the solar wind. Ganymede's magnetic field is several times
Orbit of the Moon rearward loops in the Moon's solar orbit. Considering the Earth–Moon system as a binary planet, its centre of gravity is within Earth, about or 72.6% of the Earth's radius from the centre of the Earth. This centre of gravity remains on the line between the centres of the Earth and Moon as the Earth completes its diurnal rotation. The path of the Earth–Moon system in its solar orbit is defined as the movement of this mutual centre of gravity around the sun. Consequently, Earth's centre veers inside and outside the solar orbital path during each synodic month as the Moon