How many solar systems in a galaxy
Pro Research Analysisby 
Searched over 200M research papers
Number of Solar Systems in a Galaxy
Introduction to Galactic Solar Systems
Understanding the number of solar systems within a galaxy is a fundamental question in astronomy. A solar system, defined as a star and its orbiting planets, is a common structure in the universe. Recent research has provided insights into the prevalence of these systems within our galaxy, the Milky Way.
Prevalence of Planetary Systems
Estimations and Theories
Early theories, such as those proposed by Jeans, suggested a very limited number of planetary systems in the galaxy. For instance, it was once hypothesized that there could be at most two planetary systems in the entire galactic system1. However, this theory has been largely debunked by more recent calculations and observations.
Modern Calculations
Contemporary research indicates that planetary systems are far more common. It is now estimated that approximately one in six stars could be accompanied by planets. This would imply that the number of planetary systems in our galaxy is not in the single digits but rather in the tens of thousands of millions1. This significant increase in estimated numbers highlights the vastness and richness of our galaxy in terms of planetary systems.
The Solar System's Context
The Milky Way and Beyond
Our solar system is just one of potentially billions within the Milky Way galaxy. The Sun, our central star, is one among billions of stars in this vast expanse. The discovery that planets are common in our galaxy further supports the idea that solar systems are a widespread phenomenon2. This understanding places our solar system in a broader context, emphasizing that it is not unique but rather a typical example of a galactic planetary system.
Conclusion
In summary, the number of solar systems in a galaxy like the Milky Way is estimated to be in the tens of thousands of millions. This estimation is based on the prevalence of stars with accompanying planets, which is now understood to be a common occurrence. The early theories suggesting a very limited number of planetary systems have been replaced by a more accurate understanding of the galaxy's structure and composition.
Sources and full results
Most relevant research papers on this topic
OBSERVATIONS OF HIERARCHICAL SOLAR-TYPE MULTIPLE STAR SYSTEMS
The PALM-3000 adaptive optics system at the 5 m Hale telescope has confirmed 20 multiple solar-type star systems, confirming their physical status and resolving five close sub-systems.
Highly CitedAbout 30% of Sun-like Stars Have Kepler-like Planetary Systems: A Study of Their Intrinsic Architecture
About 30% of Sun-like stars have Kepler-like planets, and the fewer planets in a system, the hotter it is dynamically.
Highly CitedThe HARPS search for southern extra-solar planets - XVII. Super-Earth and Neptune-mass planets in multiple planet systems HD 47 186 and HD 181 433
Two new multiple planet systems have been detected orbiting solar-like stars, increasing the number of close-in low-mass exoplanets to 20 and highlighting the presence of 80% in multiple planetary systems.
Highly Cited