But what is called "near-by" is quite relative, because we can ask "near-by compared to what?"
Well, compared to far, far, far, far away for example?
Never-the-less, astronomers are happy to have discovered the most earth-like planet orbiting a star as only one of several planets in that distant (or close?) solar system.
The red dwarf star Gliese 581 has not only six known planets, but it also has at least one planet that orbits at a distance that places it in what is called the habitable zone.
That zone is also called the Goldilocks zone, because planets within that zone are at a distance from the star so as to allow liquid water to exist in some places on those planets, which in itself makes it an interesting solar system:
Gliese 581 is a red dwarf located 20.5 light-years from Earth, in the constellation Libra. Like other red dwarfs, it's smaller and much dimmer than our sun. Scientists believe Gliese 581 is old — at least a few billion years — and relatively stable. Both are qualities conducive to the evolution of life, scientists have said.(Space; also White Paper PDF). So how excited should we get about this discovery, in terms of potential human space travel to check it out?
As was pointed out in an earlier post on Ecocosmology blog:
For example, our B.C.E. technology (burning chemicals to produce energy (thrust) in rockets) which we fondly call rocket science, is not going to get us to the part of "the block" where the "near" star with planet GJ-1214b is.(A Lovely Planet In The Neighborhood?). What that means is since the star Gliese 581 is half the distance to GJ-1214b, it would "only" take us 352,957.27 years (705,914.53 / 2) to get there, ONE WAY.
Light travels at about 670,618,800 miles an hour (186,283 miles per second x 60 x 60) or 5,878,644,400,800 per year (670,618,800 x 24 x 365.25). A planet orbiting a star 40 "light years" away, then, is 235,145,776,032,000 (5,878,644,400,800 x 40) miles away.
Our spacecraft Voyager I and II travel at about 38,000 miles per hour, or 333,108,000 miles a year (38,000 x 24 x 365.25).
So it would take them 705,914.53 years (235,145,776,032,000 / 333,108,000), one way, to get to that planet salaried scientists say is "on our block".
Many scientists' salaries come from military sources in the Pentagon budget. The military scientists are only concerned with being able to destroy things on the earth, so "rocket science" is the apex of their intellect. If it kills better than the last one they love it.
We see, then, that the science produced by our political systems on Earth is so heavily controlled by military considerations that we have unwisely focused on chemical propulsion for space travel.
Thus, we are still way, way out of range and cannot realistically consider travelling to Gliese 581, or any other star system for that matter, even though our continued existence depends upon the ability to do so.
Humanity has expressed hope, through the SETI program, to find another planet out there where a civilization exists that has the ability to do competent space travel, and could help us continue to survive when it gets close to the time when our solar system catastrophically dies out.
For now, then, all that any warmonger controlled planets like Earth can ask of "near-by" planets is the Mr. Robinson question, "would you be my neighbour?"