“As I remember it, the serial numbers are set like this: the prefix digits represent the order of discovery; the letters J, E, and X stand for Jupiter-type planets, Earth-type planets, and other planets, respectively; and the digits following the letter indicate the number of that type of planet in the system.” “That’s right. 244J2E1 is a star with three planets, two of them Jupiter-type and one Earth-type.”
