A stellar puzzle

This story is at www.sciencenews.org/view/feature/id/74449/title/Stellar_oddballs.html … the Kepler spacecraft has found a mystery – described as a treasury of wonders, even a freak show of oddball stars. The primary mission of Kepler is to look for planets orbiting around stars – that may have life. So far it has found 1200 planets, betrayed by small repetitive dips in the brightness of parent stars as the shadow of a planet crossing a star's face. A lot of stars do not have planets, it would seem – and there are so many stars on display with unexplained variations in brightness that have yet to be catalogued and thought about. There are stars that pulsate, double stars that are so close to each other that streams of plasma flow between them, immense star spots, unlikely rotations, collapsed white dwarfs etc. However, at www.nytimes.com/2011/05/19/science/space/19planets.html?_r=4&pagewanted=… where we learn that space it littered with hundreds of billions of planets that have been ejected from planetary systems that gave them birth according to a study in Nature by an international team of astronomers. There are two Jupiter mass planets for each of the 200 billion stars in the Milky Way galaxy, it is claimed. The technique used to discover this fact is interesting by itself, and is quite different to the Kepler spacecraft way of doing things. It involves what is called gravitational microlensing. It relies on a large object bending light and acting as a magnifying lens as predicted by Einstein's general theory of relativity. It has been asked if these are planets or failed stars but clearly there are things going on up there in the sky that until recently science had no idea – so do solar systems stay intact or do they rearrange themselves on occasion, are these lost planets loose cannons or looking around to gatecrash a family of other planets.