A galactic survey of epic proportions has concluded there are more planets than stars. The downside is that the survey only used a sample size of one – our own galaxy, the Milky Way. Which means the survey could be highly unreliable.

A team of scientists led by Arnaud Cassan at the Institute of Astrophysics in Paris, published their research in the journal Nature. They estimated each star has 1.6 planets. Looking up to the night sky, the vast array of stars we see have planets that are invisible to the naked eye, and even with telescopes, a lot of the planets are still invisible. The group used gravitational microlensing to deduce the number of planets in their sample. Microlensing occurs when light from an object (in this case, a star) is amplified or ”bent” by the gravitational effect of another star pasing in front of it when seen from earth.

The survey estimated that there were 800 billion planets in the Milky Way and 100 billion times that for the entire Universe. Which would give us a rough total for planets of;


which is 80,000 trillion planets.

The Milky Way galaxy alone could contain 100 billion exoplanets – planets that could be suitable for biological life.

You can see where I”m going with this. With so many planets in existence, the odds of us being alone in the universe are getting really, really, really slim. If we are the only life in the complete universe, then that means our odds at the beginning were 1 in 80,000 trillion planets.

The study also suggested that low mass planets like earth were more common than giants like Jupiter.

Artist Impression

Artist illustration showing how planets are the rule rather than the exception.Credit: NASA, ESA, and M. Kornmesser (ESO)