"Superhabitable" planets

"Earth is not necessarily the best planet in the universe. Researchers have identified two dozen planets outside our solar system that may have conditions more suitable for life than our own. Some of these orbit stars that may be better than even our sun.

A study led by Washington State University scientist Dirk Schulze-Makuch recently published in the journal Astrobiology details characteristics of potential "superhabitable" planets, that include those that are older, a little larger, slightly warmer and possibly wetter than Earth. Life could also more easily thrive on planets that circle more slowly changing stars with longer lifespans than our sun...

Water is key to life and the authors argue that a little more of it would help, especially in the form of moisture, clouds and humidity. A slightly overall warmer temperature, a mean surface temperature of about 5 degrees Celsius (or about 8 degrees Fahrenheit) greater than Earth, together with the additional moisture, would be also better for life. This warmth and moisture preference is seen on Earth with the greater biodiversity in tropical rain forests than in colder, drier areas...

Among the 24 top planet candidates none of them meet all the criteria for superhabitable planets, but one has four of the critical characteristics, making it possibly much more comfortable for life than our home planet.

"It's sometimes difficult to convey this principle of superhabitable planets because we think we have the best planet," said Schulze-Makuch. "We have a great number of complex and diverse lifeforms, and many that can survive in extreme environments. It is good to have adaptable life, but that doesn't mean that we have the best of everything.""