Now that we’re finding exoplanets (planets around stars outside of our solar system) in abundance, the next question we're beginning to ask is how habitable are those planets? And knowing what we know about water and its ability to sustain life, the most important point is whether these planets have the right environment to sustain liquid water. From what we know about habitable zones, we’ve laid out rules for what the perfect habitable exoplanet might look like and where it might be. However, thanks to some new research and computer modeling, our concept of the habitable zone is changing: some planets may be outside of what we consider the habitable zone, but would still be habitable, especially if they wobble.
These planets would normally be thrown out of consideration for the capability of sustaining life, but researchers think that if these planets wobble around a lot on their axes, it might keep them from being completely turned to ice. New computer models developed by Weber State University in Utah looked at this phenomenon by using planets similar to Earth’s size that orbit a star with a few large gas planets in the near vicinity. The idea is that those large planets pull against the Earth-sized planet and make its axis tilt at a more extreme angle over very short amounts of time, geologically speaking: mere tens of thousands of years.
This might sound strange, but we’ve already discovered a few planets doing this around a star called Upsilon Andromedae: two of its planets are tilted at 30 degrees relative to each other. Computer models showed that this sort of progressive wobble affects the planet’s climate because it allows more sunlight to reach the poles, causing ice to melt there. The models also suggested that such a planet could be habitable even if it is twice as far from its star as Earth is from the Sun. This confirms a recent theory that potentially habitable planets are much more common than we ever thought possible.