Discovering a new planet

Unit States have discovered a planet 20 light years that could satisfasy the condition necessary for life.
It is located at the right distance from its sun particular, the star Gliese 581, which would have the right temperature for that water and gravity necessary for existence of an atmosphere.
However, this planet most like Earth yet discovered, has some differences. His particular yer lasts only 37 days, and does not turn on itself, so that part is always another day and night.