According to astronomers, the Earth’s home of the Milky Way galaxy already contains hundreds of millions of planets similar to that of Earth. However, the astronomers believe that this only represents a small fraction of the total number of such planets that might develop throughout the universe in the future.
This prediction was made as astronomers used data that was obtained from the Hubble Space Telescope. Researchers used the telescope to estimate the rates of star and planet formation that had already occurred within the universe.
The data that was obtained was combined with data from prior studies that had produced estimates regarding the amounts of hydrogen and helium in the universe which is still left over from the big bang. Scientists say that this hydrogen and helium will eventually go on to produce planets and stars.
Based on previous research, when our solar system formed roughly 4.6 billion years ago, only about 39% of the hydrogen and helium within the Milky Way galaxy had collapsed to form into clouds that would later evolve into stars.
Using these numbers, scientists determined that 61% of the hydrogen and helium contained in the Milky Way galaxy was still available to form future solar systems. Such solar systems could possibly contain planets that are similar to that of Earth, making them suitable for supporting life.
Meanwhile, in the universe as a whole, only about 8% of the total hydrogen and helium had been used by the time that the Earth had been formed. Scientists believe that the other 92% will eventually form into stars, many of which will support solar systems that will contain billions of planets similar to that of Earth.
Thus, only a small fraction of planets similar to Earth have been formed so far, and billions more will be formed in the universe in the future.
Scientists estimate that the universe is about 13.8 billion years old.