There is a flurry of articles out this morning about the discovery of an “Earth-like” planet in old data from the now dead Kepler Space Telescope. Here is an artist’s rendering of it.
Some of you may remember that I recently completed a science fiction novel. I am currently sending it to the agencies who represent my favorite authors. I went to a lot of trouble to make the science of the book at least plausible, including trying to find an Earth-like planet. The first thing I did was look for planets in what is called the habitable or “Goldilocks” zone. this is the orbit range within which water is in a liquid state, so presumably life as we know it could flourish.
Unfortunately, all the planets we have discovered to date which reside within this zone also orbit red dwarf stars. So does the one in the articles mentioned above. This is a problem because red dwarf stars are much cooler than our sun, so the Goldilocks zone is much closer. This means that any planet within that zone is tidally locked like Mercury. Tidally locked planets have an orbit and rotation which are in sync so that one side of the planet always faces the sun, and one away from it. Not Earth-like.
One side of a tidally locked planet would be blazing hot, and the other bitter cold. There would likely be a temperate band around the middle where conditions would somewhat resemble those of Earth, so life could exist, but it would exist in permanent dawn or twilight.
Not a bad thing, and an interesting place to site a science fiction story, but not what I wanted, so I searched instead for a G-Type (sun-like) star. I chose Chara, which is about 27 light years from Earth. As yet we have detected no planets orbiting Chara, so I put some there. My story takes place on Chara IV.