Interstellar radioactive material has been found in recently fallen Antarctic snow. The stunning discovery has thrilled scientists who say the rare substance fell to Earth in the form of space dust less than 20 years ago. The discovery of the rare isotope of iron, iron-60, backs up previous research which found that the substance was generated by supernovae, strong stellar explosions, within the last few million years and should be present in geological formations on Earth. Researchers from Germany wanted to see if iron-60 created in stellar explosions continues to reach Earth from space. They thought there could be some in dust particles in the Local Interstellar Cloud, an area of interstellar space through which the Solar System is currently traveling, and theorized that these particles should land on Earth as it speeds past them. The scientists took about half a tonne of snow from near the Kohnen polar research station in the Antarctic, an uncontaminated site. They melted it in