Exoplanets Found in Habitable Zone Are More Common Than Once Thought


Astronomers have discovered thousands of exoplanets in the Milky Way Galaxy over the last few decades. By using periodograms and spectrography to analyze the validity of these planetary systems, researchers have found out that of the 100 billion stars in the galaxy, they believe a few billion of them have up to three exoplanets within the habitable zone. The habitable zone , or “Goldilocks zone,” is the area in which liquid water can exist on a planet, insofar as the planet is in the correct orbit around its host star that surface temperatures are between freezing and boiling. Thus, carbon-based life could exist on these exoplanets. This means that exoplanets found in the habitable zone in an extra-solar systems are more common than once thought. The study was published in the Monthly Notices of the Royal Astronomical Society.

By using NASA’s highly advanced Kepler satellite, astronomers have located nearly 1,000 exoplanets around stars that are floating about the Milky Way, as well as 3,000 other hopeful habitable worlds. A majority of the planetary systems are composed of two to six planets. Though, the documented stars could potentially have other planets that are yet to be observed due to stellar background radiation that would mask their presence.

The habitable zone is a very important factor to astronomers. In order to measure if the temperature on an exoplanet is too hot or too cold on the surface, a team of researchers from the Australian National University and the Niels Bohr Institute, located at the University of Copenhagen, used a new version of a 250-year-old method to calculate the viability for life on an exoplanet. This method is called the Titius-Bode law.

The Titius-Bode law was surmised in 1770, and anticipated the exact location of Uranus before it was ever discovered. The law states that there is a ratio between the orbital periods of planets in a system. Therefore, the ratio between the orbital period of the first and second planet is exactly the same as the ratio equivalent between the second and third planet – a multiple of two. The law applies to any number of planets in a system. In regards to the law, this means that if the orbit of Jupiter is calculated, and there is a multiple of four in the orbital gap in between Jupiter and Neptune, this must mean a planet is located in between the two aforementioned planets because the orbital stratification must be in multiples of two. Thus, calculating the position of Uranus.

exoplanetSteffen Jacobsen, a doctorate student at the Niels Bohr Institute, stated the team used this method to calculate the positions of missing exoplanets in 151 planetary systems, where the Kepler satellite showed signs of systems which had between three and six planets. The Titius-Bode law fit 84 percent of these systems, which calculated the positions of the missing exoplanets. Jacobsen stated the team found a correlation between the exoplanets in the system that fit the correlation of multiples of two in between orbital gaps of exoplanets.

The astronomers stated that if these calculations are used in other areas in the galaxy, it could mean there are billions of stars with exoplanets that orbit their host star in the habitable zone. Jacobsen explained he and his team of researchers want to encourage other astronomers to study the data that came from the Kepler satellite more thoroughly to find missing exoplanets. Furthermore, he said there are 40 other planetary systems they have predicted should be in the habitable zone where liquid water can exist and carbon-based life may thrive. Therefore, exoplanets found in the habitable zone are more common than once thought.

By Alex Lemieux


National Monitor

Earth Sky


Photo by Garysan97 – Flickr License

Photo by Matt Hendrick – Flickr License

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