How many solar systems exist and what is the average number of planets in those solar systems?

Answer

Hi Hermine,

My answer to your question is valid on Monday 26 May 2008. Why? Because planets and planetary systems are discovered almost every day, and so the numbers change. Now the counter stands at 293 planets outside of our solar system. These are in about 270 systems such as our solar system. But we will discover many more in the coming years.

I will not give a statistical answer to your question about the average number of planets per system. After all, we still know very little about the planetary systems outside our own. With current techniques and telescopes, we usually only discover the heaviest planet around another star. This greatly distorts the average number per star. However, there is no reason that the number of planets around another star should be limited to one or two. We’ll know more in a few years.

Greetings,

Jean-Pierre De Greve