Milky Way may have billions of planets in habitable zone

Our Milky Way galaxy may be home to billions of planets orbiting their host stars in a habitable zone, where there could be liquid water and possibility of life, a new study has found.

Using NASA’s Kepler satellite, astronomers have found about 1,000 planets around stars in the Milky Way and they have also identified about 3,000 other potential planets.

By analysing these planetary systems, researchers from the Australian National University and the Niels Bohr Institute in Copenhagen have calculated the probability for the number of stars in the Milky Way that might have planets in the habitable zone.

“The calculations show that billions of the stars in the Milky Way will have one to three planets in the habitable zone, where there is the potential for liquid water and where life could exist,” researchers said.

Researchers made calculations based on a new version of a 250-year-old method called the Titius-Bode law which correctly calculated the position of Uranus before it was even discovered.

The law states that there is a certain ratio between the orbital periods of planets in a solar system.

Therefore, if you knew how long it takes for some of the planets to orbit around the Sun/star, you can calculate how long it takes for the other planets to orbit and can thus calculate their position in the planetary system.

“We decided to use this method to calculate the potential planetary positions in 151 planetary systems, where the Kepler satellite had found between three and six planets,” said Steffen Jacobsen, of the Niels Bohr Institute.

The researchers evaluated the number of planets in the habitable zone based on the extra planets that were added to the 151 planetary systems according to the Titius-Bode law.

They predicted a total of 228 planets in the 151 planetary systems and one to three planets in the habitable zone of each.

Of the 151 planetary systems, they made an additional check on 31 planetary systems where they had already found planets in the habitable zone or where only a single extra planet was needed to meet the requirements.

“In these 31 planetary systems that were close to the habitable zone, our calculations showed that there was an average of two planets in the habitable zone,” said Jacobsen.

“According to the statistics and the indications we have, a good share of the planets in the habitable zone will be solid planets where there might be liquid water and where life could exist,” Jacobsen added.

If you then take the calculations further out into space, it would mean that just in our galaxy, the Milky Way, there could be billions of stars with planets in the habitable zone, where there could be liquid water and where life could exist, researchers concluded.

The research was published in the journal Monthly Notices of the Royal Astronomical Society .

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