The number of confirmed planets in other star systems has reached about 6,000. But few of those planets are likely homes for life. Most are too hot, too cold, too “gassy,” or they’re zapped by too much radiation by their star.

A few planets are in the “well, maybe” category. They might be suitable for life, but the conditions aren’t perfect.

An example is a planet in the star system 82 Eridani. The system is about 20 light-years from Earth, and its star is similar to the Sun.

Astronomers have confirmed three planets in the system, with hints of more. Two of the planets are quite close to the star, so they’re too hot for life like that on Earth. But the third planet is more intriguing.

It’s about six times the mass of Earth, so it could be dense and rocky. Its average distance from the star is about a third farther than Earth’s distance from the Sun. At that range, the planet spends most of its time in the star’s habitable zone – the region where conditions are most comfortable for life.

But the planet’s orbit is so lopsided that the distance varies by more than a hundred million miles. So as the planet moves around 82 Eridani, surface temperatures range from hot enough to boil water to cold enough to freeze the entire surface. That makes it unlikely that anything lives on the planet. It is possible that life could exist below the surface – avoiding the extremes on this “yo-yoing” planet.

Script by Damond Benningfield