Astronomers at the European Southern Observatory have discovered an "Earthlike" planet orbiting star Gliese 581, only 20.5 light-years away. This planet (foreground) has mass 5 times that of Earth and orbits the star every 13 Earth-days. Because Gliese 581 is a dim red dwarf, this leads to conditions favourable to life. The planet's mean temperature is between 0 and 40 degrees Celsius, suitable for liquid water.
Our own planet occupies a very narrow habitable zone, where the porridge is neither too hot nor too cold. As we have seen before, Earth's temperature has remained comfortable because light has been slowing according to GM=tc^3. The same equation that keeps our Sun relatively stable applies to Gliese 581 and any other star. If c did not slow, the habitable zone would expand to pass Earth by. Life would have difficulty evolving on any planet anywhere.
The High Altitude Radial Velocity Planet Searcher (HARPS) mounted on the 3.6 meter telescope has discovered many planets. Around Gliese 581 it has also discovered a Neptune-sized planet, pictured in blue, orbiting the star every 5 days. In the distance another planet orbits in 84 days. The painting is very pretty; one can easily imagine some future starship enjoying this same view.
We can only imagine what sort of life would evolve here. This planet's gravity would be about 2.2 times that of Earth, so they might be more solidly built. Since the star's light is redder than ours, their eyes would be sensitive to longer wavelengths, as a snake can see in infrared. Our red would be white to them.
(ESO, are you there? I appreciate the notices but the lighting is all wrong. The "Earthlike" planet seems to be lit from a yellow Sun-like star somewhere off to the right. The blue Neptune-like planet seems to be lit from a different source entirely. Many science fiction movies make similiar mistakes. I can happlily correct this painting for you. )