The planets in our own solar system come in a wide variety of forms, and their moons are just as unique.  What kinds of worlds might be found in orbit of other stars?  To date, we know only of  gas giants like Jupiter and Saturn, although of course there is the potential for variation even here.  But by and large, these planets are of a kind.  As our knowledge and technology grows, doubtless we will discover more and more different types, each one a testament to its own special evolution.

Ironically, the first planets ever discovered were of the smaller, terrestrial type.  Rocky worlds, possibly with atmospheres, but almost certainly nothing even close to what a Jovian planet has to offer.  But these worlds orbit dead stars known as pulsars, and inded they themselves may have formed from the debris of the star's death.  Certainly, they are not places one would expect to find life.  Worlds have also been found floating free in space, unbound by any star.  However, because their presence was betrayed only by the chance passing in front of a distant star, little can be told about these bodies save that they produce no light, and their apparent size.  And once the planet has moved on, it is impossible to see again.

By far the most intriguing worlds are those that have been found to orbit stars similar to our Sun.  They may be gas giants, similar to jupiter, but that does not lessen the momentous implications.  After all, if there are other Jupiters out there, then it stands to reason that there are other Earths as well.