25 years after the seminal
intuition by Bohdan Paczynski, microlensing has rapidly evolved into
a new promise for modern astronophysics. Indeed, the detection of
celestial bodies by their gravitational effects on the light of
background sources has proved to be a very powerful tool for the
study of many aspects of our Galaxy and beyond.
The original proposal of using microlensing to estimate the amount
of baryonic dark matter in the form of compact substellar bodies is
still topical. The observation of microlensing events toward nearby
galaxies still represents a hard challenge for present observational
facilities. Very strong efforts are under way for upgrading the
current strategies in particular toward the galaxy M31.
Hundreds of microlensing events are discovered toward the Galactic
Bulge every year. This considerable amount of statistics can be used
to characterize the stellar populations of the bulge and the disc of
our Galaxy. After several years of observations, the significance of
the microlensing sample in the characterization of our Galaxy is
growing more and more.
Yet, the most intriguing perspective offered by microlensing is
represented by its power to discover new extrasolar planets of very
low mass, down to Earth-size or below. Several planetary events have
already been detected and studied, while many more are expected as
soon as future dedicated telescopes become operational.
Interestingly, microlensing is already being used to estimate the
abundance of planets around stars in the disc of our Galaxy and to
characterize their distributions in distance and mass. As the
planetary anomalies typically last only a few hours, the cooperation
among all observing groups is mandatory, in order to characterize
the events properly and maximize the scientific achievements. Even
amateur astronomers are now giving their fundamental contribution.
In this respect, microlensing stands as a perfect example of how
science can unite the whole mankind in a common path toward pure