Gravitational microlensing is a powerful method to search for and characterize exoplanets, and it was first proposed by Paczyński in 1986. We provide a brief historical excursus of microlensing, especially focused on the discoveries of free-floating planets (FFPs) in the Milky Way. We also emphasize that, thanks to the technological developments, it will allow to estimate the physical parameters (in particular the mass and distance) of FFPs towards the center of our Galaxy, through the measure of the source finite radius, Earth or satellite parallax, and/or astrometric effects.

中文翻译：

---

银河系中的自由漂浮行星

引力微透镜是一种寻找和表征系外行星的有力方法，它是由帕金斯基（Paczyński）于1986年首次提出的。我们提供了微透镜的简要历史资料，尤其着重于银河系中的自由漂浮行星（FFP）的发现。我们还强调，由于技术的发展，它可以通过测量源有限半径，地球或卫星视差来估算FFP朝向银河系中心的物理参数（尤其是质量和距离），和/或天文效应。