What percentage of the planets are extrasolar?

Extrasolar planets

Planets seem to be something completely normal in the universe. Although the faint companions in distant stars are extremely difficult to detect, the number of known exoplanets has increased rapidly in recent years: more than 4600 extrasolar planets have already been detected. Some of them are similar in size to our earth - and some of them could even contain liquid water.

Is our earth the only planet on which life exists? A look at the starry sky makes this seem very unlikely - if only because of the sheer number of stars and galaxies. How many planets there are outside of our solar system is not exactly known. Scientists only detected the first such exoplanet almost thirty years ago. On March 3, 2021, 4690 extrasolar worlds in 3465 planetary systems were already known - and the number is steadily increasing.

So far, astronomers have only looked for exoplanets in a very small area of ​​the Milky Way. The most distant are just around 6000 light years away. For comparison, our Milky Way galaxy is over 100,000 light years across. The findings so far are unlikely to be representative either: Methodologically, preference is given to large planets that are orbiting close to their central star.