Free Astronomy Magazine January-February 2021

18 ASTRO PUBLISHING able to astronomers today. Thousands of these worlds may currently be be- yond our ability to observe them, but even assuming that there are twice as many of these worlds as there are de- tected ones (there are likely to be fewer), we find that planetary sys- tems have on average less than half the number of planets contained in our own solar system. According to the results of available observations, most planetary systems are composed of only one or two planets. Having said that, it is inevitable to wonder if Less eccentric orbits in the most crowded planetary systems T here are 3200 known planetary systems as of December 2020. These systems are home to at least 5700 detected planets, 4300 of which have been confirmed. Given the limitations of current research methods, we can reasonably assume that the number of planets hosted by those same systems is actually signifi- cantly higher – we simply do not have the resolution to observe them yet. Many planets may in fact be too small or too far away from their star to be discovered with any instrument avail- by Michele Ferrara revised by Damian G. Allis NASA Solar System Ambassador