Scientists estimate that 100 to 400 billion planets exist in the Milky Way galaxy. Some studies suggest that the number of planets in the Milky Way is greater than the number of stars, proposing that an average of 1.6 planets exist per star.
In the Milky Way galaxy, approximately 8.8 billion planets are in the habitable zone. The habitable zone is an area that is an acceptable distance from the sun, which is expected to maintain optimal temperatures to support life. Scientists suggest that there are likely billions of other solar systems in the Milky Way galaxy, and billions of galaxies in the Universe.