There are six billion planets in the Galaxy.
New astronomical data indicate that only in our Milky Way galaxy there are six billion stars in the orbit of which the existence of planets similar to Earth is possible. The new research could be a major boost to the search for alien life elsewhere in outer space.
In one Milky Way galaxy, there are up to 400 billion stars, or trillions of planets. If you take our Solar system as a model, according to new research, most of these planets are likely lifeless and barren, but billions of years ago it could have been very different.
Scientists from the University of British Columbia (UBC) analyzed data from the Kepler telescope to determine the likelihood of Earth — like planets-rocky worlds that may contain water.
According to a study published in the Astronomical Journal, to be considered terrestrial, a planet must orbit a star like our Sun, known as a G-type star. In addition, the planet should be in the habitable zone, not too hot and not too cold for life. Here’s what UBC researcher Michelle Kunimoto, co-author of the new study, said about this:
“My calculations put an upper limit on the coefficient of 0.18 for Earth-type planets in the orbits of G-type stars. Estimating the prevalence of different types of planets around different stars can provide important constraints for theories of planet formation and evolution, and help optimize future missions dedicated to finding exoplanets.”
UBC astronomer Jamie Matthews added:
“Our Milky Way has 400 billion stars, with seven per cent of them being G-type. This means that at least six billion stars can have Earth-like planets in our Galaxy.”
Previous estimates suggested that the coefficient does not exceed 0.02 for Earth-type planets in the orbits of stars like the Sun. However, Ms. Kunimoto used a technique known as “direct modeling,” which allowed her to create a clearer picture.
“I started by modeling the full population of exoplanets around the stars that Kepler was looking for. I have marked each planet as “discovered” or “missed” depending on the probability that my planet search algorithm will find them.”
“After that, I compared the discovered planets with my actual catalog of planets. If the simulations produced a close match, then the initial population was likely a good representation of the actual population of planets orbiting these stars.”
The study should also shed more light on the “radius gap”:
“The radius gap shows that planets with orbital periods of less than 100 days are not 1.5-2 times the size of the Earth.”
According to Kunimoto, the radial gap exists in a much narrower range of orbital periods than previously thought. Her observations allow us to impose new constraints on the models of planetary evolution that explain the characteristics of the radial gap.