NASA’s new earthlike planet finder telescope will be looking once it is in space. Comparison data has been acquired from space by looking back at earth to see what earth looks like spectrographically. If they get a match so close, only 4 light years, try to not get caught in the stampede.
I heard they have problems with an egomaniac named eroGla! I hope they survive!
If an Earth-sized, water and habitable atmosphere containing planet is discovered in the Alpha Centauri system, that would be HUGE impetus to send probes immediately. NASA should be pulled from the basic science experiments, and pushed toward trying to make a workable magnetic field solar sail vehicle for the probes, and eventually for manned missions and colonization. Even a Project Orion with a launch site on the Moon might be considered.
The Alpha Centauri world might be the first non-Earth planet Mankind steps on, beating out Mars, if the planet is confirmed habitable.
Exoplanet ping.
Be there in 100 years? Not if it’s government work.
Kolob?
It can only have an oxygen atmosphere if it's developed life. Without plant and animal life in balance, we'd have a methane atmosphere.
But even further back along that food-chain, if we didn't have the moon, we wouldn't have waves to keep the oceans churned up, nor would we have tide-pools to concentrate the ingredients of life, all of which our current understanding of the way life formed on Earth, require.
It may be the same SIZE as the Earth, but it may share NONE of the other attributes that have developed over the past 3.5 billion years.
The development of life on Earth was a looooooong shot. And without life, it's likely to be a bare rock, if it exists at all.
Let's not forget that Mars is only marginally smaller than the Earth and it didn't have enough gravity to hold in it's atmosphere, and hence lost its oceans and possibly it's life as well.
There are a billion reasons a planet can fall apart from what we consider Earth-like.