Some Planets That Seem Life-Friendly Might Not Be. Here’s What That Means For The Search For E.T.

When looking for alien life, astronomers pay special attention to planets in the so-called “Goldilocks zone” — that is, planets that orbit their host stars at just the right distance for water to exist in a liquid state.

But a new study shows that some otherwise habitable planets might be rendered unsuitable for life because gravitational forces exerted by neighboring planets have nudged these “chaotic Earths” out of stable orbits and given them unstable climates.

“Just like people, some planets are victims of circumstance, and won’t enjoy a placid existence,” Dr. Seth Shostak, senior astronomer at the SETI Institute in Mountain View, Calif., who was not involved in the new research, told The Huffington Post in an email. “That might be bad news for them — at least in terms of harboring life over very long time periods.”

Planets go haywire. For the study, astronomers at the University of Washington built computer models of solar systems in which planets orbit their host stars in different planes. (The orbits of planets in our own solar system all lie in the same plane.)

The planets in the models had orbital periods that were integer multiples of one another, or in integer ratios. For example, if a planet orbits its host star in 200 days and another planet orbits the same star in 300 days, their orbital periods are related in a 2:3 ratio. This coordination causes the planets to pull on each other’s orbits in the same spot over and over again, which over millions of years can cause major changes in these orbits.

“What we found was that things go all haywire,” Dr. Rory Barnes, one of the astronomers and the study’s lead author, said in a written statement. “Those little perturbations that keep happening at the same point cause —> Read More