11.   Extrasolar planets, whose existence astronomers only dreamed of proving just a few years ago, are becoming almost commonplace.

12.   Extrasolar planets are generally too small to be seen with existing telescopes.

13.   If they are clever enough, Lin said, theorists who wrestle with the discoveries should gain an understanding of the reasons for such manifest diversity in extrasolar planets.

14.   If Gray is right, then a few other reputed extrasolar planets also may be illusions.

15.   It is the first of the extrasolar planets that appears to have an Earth-like orbit.

16.   Next comes an estimate of the fraction of extrasolar planets that are habitable.

17.   Objects originally identified as extrasolar planets have proved to be illusions or non-planetary objects.

18.   On the drawing board is an advanced satellite called Planet Finder that someday could send back the first pictures of Earth-type extrasolar planets.

19.   Now, new research suggests that at one time, other so-called extrasolar planets must have existed as well.

20.   The dozen or so extrasolar planets discovered so far have been detected indirectly because their gravity makes their parent stars wobble.