Unveiling the magnetic topology of prominences

Prominences are understood as plasma condensations supported against gravity by the magnetic field. This magnetic field not only gives birth to those solar features but it is responsible of most of the dynamics and evolution of the prominence itself , but also of its coronal and photospheric surroundings. Despite such starring role, prominence magnetic fields are scarcely measured. In this talk I will bring memories of the initial measurements of Leroy and Bommier and review recent works using the Hanle effect to directly infer the magnetic field in prominences and spicules. The measurement of this field as well as the background photospheric field at high sensitivity are constraining the models of the magnetic topology underlying prominences.