There are 9 planets within our solar system and all of them are rotating around the sun thanks to its natural gravitational pull. Thats a pretty unique setup and until the mid 90s the idea of other solar systems in distant galaxies was mere speculation.

That speculation became a reality in 1995 when the first extra-solar planet called 51 Pegasi b was discovered. What exactly is an extra-solar planet then ? Well simply put it’s a planet that not only exists outside of our solar system but also has its own central star which it rotates around. These planets are known as exoplanets or extra-solar planets.

Most exoplanets are discovered by chance but certain signs such as the regular dimming of a star can indicate whether an exoplanet might exist. When a planet moves in a regular transit around a central star its mass causes the dimming of the central star. This dimming is a key sign and indicator of possible exoplanet existance.

Since 1995 more than 200 extra-solar planets have been found and all of these are as big if not bigger than Jupiter. As technology improves perhaps smaller exo-planets can also be found but for now the mere existance of these exoplanets is an amazing discovery and really brings the subject of extra terrestrial life to the forefront of scientific discussion.