The planet PSR J1719-1438 b is mostly made up of compressed carbon, or diamond. It is about 4,000 light years away from Earth and is about the same size as Jupiter, though it is 20 times as dense. The planet is actually the leftover core of a white dwarf that was part of a binary pulsar system. When the other part of the system became a supernova, PSR J1719-1438 b became a white dwarf and stabilized into its current form. It's probably one of the most beautiful and expensive planets in human standards anyway. But the fact that the planet is so dense means there's no way for us to harvest these expensive rocks and diamonds even if we wanted to.
More facts about PSR J1719-1438 b and other unusual planets:
- PSR J1719-1438 b actually has a very tight orbit around its host star, so much so that its entire orbit would fit inside the Sun.
- The coldest known planet outside the Solar System is OGLE-2005-BLG-390L b, which is about five times the size of Earth and has a surface temperature of minus-364° Fahrenheit (minus-220° Celsius). The hottest known planet is WASP-12b, which is about 4,000° Fahrenheit (about 2,200° Celsius).
- The planet HAT-P-1 is about 1.75 times wider than Jupiter but is believed to be lighter than what a cork ball of the same size would weigh.