Does every planet have a magnetic field?

Mars does not have a magnetic field. It almost certainly did once - we still see crustal remnants of this ancient field in some rocks - but then its liquid metallic core cooled and solidified. Jupiter has a magnetic field. It's incredibly strong - much stronger than any other planet. read more

Magnetic fields protect a planet from the charged particles streaming out from the Sun in the form of the solar wind. The particles are deflected outwards by the magnetic field lines. Earth has a strong magnetic field because it has a liquid conducting core composed of iron-nickel that rotates swiftly every 24 hours. read more

No, not all planets have magnetic fields. The four gas giants have extremely strong magnetic fields, Earth has a moderately strong magnetic field, Mercury has an extremely weak field, but Venus and Mars have almost no measurable fields. read more

On Earth we use the planets magnetic field for navigation, but there may be some planets where you would get lost. read more