Ahh, the habitable zone. Where everything is warm but not too warm, where water is free to be a liquid, where life can feel free to procreate without danger or freezing of boiling. This is the most important place for a planet to be if the planet wants little things crawling around and breathing on it. Recent studies on Red Dwarf type stars (Class M stars) by Manoh Joshi and Robert Haberle, have shown that, due to the type of light emitted by these stars, their planets can exist in a habitable zone 10% to 30% farther from their star than previously thought possible. This is extremely important because up to 80% of the main sequence of stars are Red Dwarf type stars. Red Dwarf stars are extremely common stars that are smaller then our own Sun, because of their size they also have a longer lifespan (100 to 1000 times the life of our Sun) and a red color. Our closest star neighbor, Proxima Centauri is a Red Dwarf type star, as well as 20 of the nearest 30 stars. Unfortunately due to their small size and low luminosity, no Red Dwarf type stars can be seen without the use of a telescope.
We have found planets in the habitable zone of Red Dwarf stars. Gliese 581 is a good example especially because it is only about 20 light years away from Earth. The planets Gliese 581 C, G, and D may all exist within the habitable zone of that star. It was recently thought that Gliese 581 D was on the outer edge of the habitable zone and probably couldn’t support life, but with these new findings it puts this planet clearly into the habitable zone. While Gliese 581 D is probably too large to be a rocky planet, it is quite possible that it could have moons that would be habitable.
We need as many habitable planets as close to Earth as possible if we are ever going to have a possibility of colonizing them for human use. This new discovery about the way light acts around stars with different spectra allows us to refine our searches to places that are more likely to support life and this also increases our possibilities significantly that someday we will be able to reach out to another planet to make sure that we will be able to continue humanity for billions of years to come.