Scientists announced Thursday the discovery of a planet in the Milky Way galaxy that appears to be a solid diamond, dpa reported. But, at 4,000 light years from Earth, it is out of human reach - for now. A multinational team of planet-hunters tracked down the orb and established that it was not only the densest planet ever discovered but also that it was made of carbon and crystallized oxygen. One of the densest forms of carbon is diamond, formed under fierce compression, leading experts to conclude that the unnamed planet was made of diamond. The item is too distant to see from earth: one light year is about 10 trillion kilometres. The find, using the 64-metre-diametre Parkes radio-telescope in Australia, was made public in the US journal Science. German scientists in Bonn were part of the team that interpreted the data. The planet orbits a newly discovered pulsar - or very dense star - in the constellation Serpens. Astronomers believe the planet is the remnant of a much bigger star which probably used to be in mutual orbit with pulsar PSR J1719-1438 in a double-star system. Oscillations in the radio signal from the pulsar convinced scientists that it was being orbited at high speed by an object half as big as Jupiter in our own solar system. The orbit time is just 2 hours and 10 minutes.