Australian astronomers said they have spotted an exotic planet that is believed to be made of diamond in our galactic backyard. The sparkling world 4,000 light years away is 60,000 kilometers in diameter, five times that of the Earth, and is thought to be all that remains of a once-massive star which collapsed and was crunched down into crystalline. An international team lead by Matthew Bailes, from Swinburne University of Technology in Melbourne, said they have discovered a low-mass but dense object in orbit around a rapidly-rotating neutron star. He said the new planet is far denser than any other known so far and consists largely of carbon. The findings were reported in the journal Science.