Most stars in the Milky Way Galaxy are accompanied by one or more planets, according to a new study. In addition, the research finds that alien worlds are often found within the habitable zone of their solar systems, where liquid water is most likely to exist. This finding, if confirmed, could suggest that alien life may be more common than many astronomers currently believe.

Many astronomers believe that alien life is most likely to develop on worlds that are within the so-called Goldilocks Zone from their parent stars. These are the range of distances where temperatures are neither too hot nor cold for water to exist.

Our own solar system is starting to show that liquid water can exist in worlds far from a sun, as evidence of massive oceans on Jupiter's moon Ganymede has recently been detected by astronomers.

Researchers from the Australian National University and the Niels Bohr Institute at the University of Copenhagen estimate that billions of stars in our galaxy are accompanied by between one and three planets in their habitable zone.

The Titus-Bode Law was developed around the year 1770. This hypothesis predicts how planets in a solar system are spread out from their parent star. This law successfully predicted the orbits of Uranus and the dwarf planet Ceres. However, the formula failed to predict the location of Neptune.

Researchers applied the formula to 1,000 confirmed exoplanets, as well as 3,000 suspected alien worlds. A total of 151 solar systems containing between three and six planets were also examined, and 124 of these families of planets were found to be in close approximation to predictions made by the hypothesis.

The Kepler Space Telescope, launched in 2009, was used to find more than 1,000 confirmed exoplanets. Many of the systems found by the observatory contain between two and six planets, but many of these solar systems likely contain additional planets that have not yet been detected. Using the 250 year-old law, it may be possible to predict where these additional worlds may be located.

"Using T-B's law we tried to predict where there could be more planets further out in the planetary systems. But we only made calculations for planets where there is a good chance that you can see them with the Kepler satellite," Steffen Kjær Jacobsen of the University of Copenhagen said.

The group was able to develop predictions for 228 "missing" planets in 151 systems.

Analysis of Kepler data utilizing the Titus-Bode Law was published in the Monthly Notices of the Royal Astronomical Society.