A few decades ago, astronomers weren’t sure that other planets exist in our galaxy except for the ones present in our Solar System. In other words, they suspected that exoplanets exist (planets from other solar systems), but they weren’t convinced.
We all have to admit that the Milky Way galaxy is pretty huge compared to Earth. Having a diameter of about 100,000 light-years, our galaxy could host many more planets than many thought possible. Most of the exoplanets from the Milky Way discovered by astronomers so far are relatively close to our Solar System. The huge size of the galaxy is what caused astronomers to not find exoplanets that are too far away. But according to SciTechDaily.com, a new discovery offers more opportunities for exploring those hidden and remote worlds.
Using gravitational microlensing
Researchers led by NASA and the Osaka University have used observations based on gravitational microlensing to determine how planet-hosting probability can vary with the distance from the Galactic center. Gravitational microlensing implies that planets can act as lenses, meaning that they bend and magnify the light coming from distant stars. Cold planets like those similar to Jupiter and Neptune can be detected by this method.

Daisuke Suzuki, who is co-author of the new study, declared as quoted by SciTechDaily.com:
Gravitational microlensing currently provides the only way to investigate the distribution of planets in the Milky Way,
But until now, little is known mainly because of the difficulty in measuring the distance to planets that are more than 10,000 light years from the Sun.
Wikipedia informs us that as of September 1st, 2021, there are 4,834 confirmed planets that exist in other solar systems.
The new study was published in The Astrophysical Journal Letters.