A planet which is almost Earth's Duplicate !!

Do you know astronomers and scientist have discovered a planet, named Gliese 581g which is almost similar to Earth. And this news was told by team at the University of California, Santa Cruz, and the Carnegie Institution of Washington to the world. The reasons I say almost similar to Earth but not exactly same are as follows,

1. The planet discovered doesn't belong to our solar system.
2. The newly discovered planet revolves round the dwarf planet Gliese 581.
3. Gliese 581g's mass is 3 times that of Earth's mass, that is around 17.9226 * 10^24 kilograms (since earth's mass is 5.9742 * 10^24 kilograms and 17.9226 * 10^24 = 3 * 5.9742 * 10^24).
4. The average temperature as estimated by the astronomers is from -24 to 10 degrees Fahrenheit, that is around -31 to -12 degrees Celsius.
5. It is almost 20 light years away from Earth, that is around 1.89210568 × 10^14 Kilometers (since 1 light year=9.4605284 × 10^12 Kilometers).
6. Gliese 581g is rocky and the gravity is similar to that of Earth.

Now, what is the problem ?
Till now astronomers are not successful in detecting water on this planet.

So, still the biggest question with respect to astronomy is again unanswered, that is Is there any other planet which supports life?

And the mystery of Universe continues !!