Habitable planets

Space.com explains a new idea that the “goldilocks” zone around suns may be different than previously thought.

Some extrasolar planets that one might assume are too cold to host life could in fact be made habitable by a squishing effect from their stars, a new study found.

A planet’s midsection gets stretched out by its star’s gravity so that its shape is slightly more like a cigar than a sphere. Some planets travel non-circular, or elongated paths around their stars. As such a world moves closer to the star, it stretches more, and when it moves farther away, the stretching decreases.

When a planet’s orbit is particularly oblong, the stretching changes are so great that its interior warms up in a process called tidal heating.

“It’s basically the same effect as when you bend a paper clip, and it gets hot inside,” said researcher Brian Jackson of the University of Arizona’s Lunar and Planetary Laboratory.

Jackson and colleagues created a computer model to simulate this effect on exoplanets, and found that the process could shift the range and distance of the “habitable zone” around a star in which planets would have the right temperatures needed to harbor life.