Six Billion Earth-Like Planets in the Milky Way Galaxy?

Astronomers have estimated that there are almost six billion Earth-like exoplanets scattered throughout our galaxy based on a new study. However, the Milky Way has up 400 billion stars. So, even if there are six billion Earth-like planets, they are still spread far and wide throughout our vast galaxy. An Earth-like world is one that’s rocky, roughly the same size as Earth, and that orbits a Sun-like, or G-Type, star. Also, it’s worth noting that the most common type of exoplanet we’ve detected is a Neptune-size planet far from the habitable zone.

Moreover, there might be about one Earth-like planet for every five Sun-like stars in the Milky Way galaxy, according to the study published in the Astronomical journal. Also, the Researchers used data from NASA’s Kepler mission to calculate the potential number of planets in our galaxy that are around the same size as Earth and orbit their Sun-like star in its habitable zone, the region around the star that creates perfect surface temperature condition to host liquid water.

Michelle Kunimoto from the University of British Columbia explains in a statement, “Estimating how common different kinds of planets are around different stars can provide important constraints on planet formation and evolution theories, and help optimize future missions dedicated to finding exoplanets.” Kunimoto explains further that she then “compared the detected planets to my actual catalogue of planets. If the stimulation produced a close match, then the initial population was likely a good representation of the actual population of planets orbiting those stars.”

Meanwhile, the researchers used a technique known as ‘forward modelling’ which led them to a more accurate estimate as it is less likely to miss a planet compared to other techniques. Researchers first simulated all the exoplanets around stars found by Kepler and marked these individual planets as ‘detected’ or ‘missed’ depending on the likelihood of their search algorithm finding them. Previously, studies have estimated that there could be about 0.02 potentially habitable Earth-like per Sun-like stars but the new estimate brings that number up to 0.18 Earth-like planets per Sun-like star.

Besides, Jaymie Matthews, the co-author of the study elaborates on the approximated number of Earth-like planets stating that the “Milky Way has as many as 400 billion stars, with seven percent of them being G-type. That means less than six billion stars may have Earth-like planets in our Galaxy.”