2 years ago
Last edited at 8:11AM on 3/16/2012
Voyager 1 is the farthest human made object from Earth. It is now far beyond Pluto orbit (approx 3 times farther). It is still sending back data. However, it would take several thousand years for it to reach the nearest stars.
Using current technology, astronomers can only guess if the planets orbiting other stars can harbor life (i.e. they have an atmosphere and liquid water). So they focus on finding Earth sized planets orbiting in the habitable zone of the star and this task is at the limits of the current technology.
Earth is an quot;M class planetquot; meaning it#039;s habitable by humans due to its atmosphere, oceans, forests and a lot more. So the answer to your question is astronomers focus on finding M class planets.