There could be billions of Earth-like planets in our galaxy

Scientists are trying to find habitable planets like the earth in our universe so that we could possibly find another planet to call home.

A new research conducted by researchers from Penn State University highlights promising results about the existence of earth-like planets in our universe. They expect that there can be about one planet for every 33 stars. Let's get into the details. 

How have they found earth-like planets in the universe? 

If you remember, NASA sent up the Kepler space telescope in 2009 to find earth-like planets orbiting the stars in our universe. The telescope discovered hundreds of thousands of stars and planets with a wide variety of sizes, compositions, and orbits. The mission ended in 2018 after it ran out of fuel. 

Researchers wanted to use those discoveries from Kepler to improve their understanding of planet formation and to plan future missions in our search for earth-like planets. But according to Eric B. Ford, professor of astronomy and astrophysics at Penn State, and one of the leaders of the research team, "Simply counting exoplanets of a given size or orbital distance is misleading, since it’s much harder to find small planets far from their star than to find large planets close to their star.”

To overcome this problem, researchers designed a new method to find the occurrence rate of planets. The new model simulates the universe of stars and then observes these simulated universes to determine how many of the planets would have been discovered by Kepler in each universe.  

Danley Hsu, first author of the paper, says, “We used the final catalog of planets identified by Kepler and improved star properties from the European Space Agency’s Gaia spacecraft to build our simulations,”. 

He also added, "By comparing the results to the planets cataloged by Kepler, we characterized the rate of planets per star and how that depends on planet size and orbital distance. Our novel approach allowed the team to account for several effects that have not been included in previous studies.”

What did the simulation find? 

The simulation created by researchers looked for planets with a size similar (three-quarters to one-and-a-half times) to the earth with orbital periods of 237 to 500 days. It found that these types of planets occur in approximately one-in-four stars. The model quantifies the uncertainty in the simulation and suggests that the range of finding an earth-like planet varies from as low as about one planet for every 33 stars, to as high as nearly one planet for every two stars. 

If we estimate the number of stars in our universe to be hundred billion, we can expect 10 billion earth-like planets to exist in the universe.

How is the discovery of planets going to help? 

The stars and planets discovered by the Kepler mission are too far away to infer more details such as the composition and atmosphere. However, knowing the rate of occurrence of these planets will help in designing our future astronomical missions.  

The rate of occurrence of these planets were found with the help of Kepler's data. 

The researchers are looking for biomarkers in the habitable zone of a star system. Biomarkers are molecules that indicate the existence of life, and the habitable zone is the range of orbital distances from the parent star that might help in producing liquid on the surface of these planets.  

According to Ford, "Searching for evidence of life on Earth-size planets in the habitable zone of sun-like stars will require a large new space mission.”