Ancient Planet

Earth is four and a half billion years old. On the timescale of the universe, that makes it a youngster. The earliest planets probably were born more than eight billion years earlier — when the universe was only about one billion years old.
One of the oldest planets yet discovered orbits a pair of dead stars. The system is known as PSR B1620-26. It’s in an ancient star cluster that’s more than 12,000 light-years away.
The planet is bigger than Jupiter, the giant of our own solar system. And it has an interesting history.
It probably was born around a Sun-like star. The system zipped through the densely packed center of the star cluster. There, it passed close to a binary — two stars locked in orbit around each other. One member of the system was a neutron star — the corpse of an exploded star. In a complex gravitational dance, the neutron star changed partners. It grabbed the Sun-like star and its planet, and kicked out its original companion.
Later, the planet’s original star reached