Exoplanets or “extrasolar planets” are planets found outside our solar system. They are designated by affixing a lowercase letter, starting from “b” towards “z” depending on order of discovery, to their parent star’s Flamsteed designation or catalogue numbers.
When PSR1257 + 12 B and PSR1257 + 12 C (they used uppercase letters for these very first ones because they did not yet use the current nomenclature), and later 51 Pegasi b, the first confirmed exoplanets were discovered in the early 1990’s, they were hailed as the most significant breakthroughs in the field of Astronomy since the Copernican Revolution and caused an uproar in the scientific community, and revived hopes of finding Earth-like planets and perhaps life outside the Solar System. Before those discoveries extrasolar planets were deemed nonexistent by most reputable astronomers and mere mention of their existence was treated as science fiction such that no self-respecting scientist took them seriously until relatively recently. Since then Exoplanetology, the study of exoplanets has evolved rapidly into a new branch of Astronomy, uncovering more than 400 such planets (30 of which in the month of October 2009 alone), but most of them were disappointingly similar to the first ones: hot bloated gas giants revolving very close to their star with orbital periods measured in days – sometimes termed “roasters,” and brown dwarves – failed stars which can be easily mistaken for the most massive planets.
The most plausible explanation for this is that the commonly used indirect methods of exoplanet detection are biased towards large, massive objects with short orbital periods which make them the easiest to identify. Every once in a while though, with the help of advanced technology and new innovative means of improving our detective capabilities and a bit of luck we get a few surprises:
PSR B1620-26 b (discovered: May 30, 1993, confirmed: July 10, 2003)
PSR B1620-26 b, nicknamed “Methuselah” for biblical reasons, is the oldest exoplanet found to date at 13 billion years old, possibly the oldest ever considering the Universe itself is only a little older at 13.7 billion years old! It was found deep inside the core of what is called a “globular cluster” of stars, which are composed of the very first stars that were formed right after the Big Bang. And based on our knowledge of planet formation planets are born soon after their parent star, so if the exoplanet’s star is really old, then the planet itself must be really old as well. It was confirmed to be a planet only in 2003 which is good news for planet-hunters because if planets can be readily formed as quickly as stars just after the Big Bang then they must be as common too.