Planets may form from material spewed from the explosive death of a star, US astronomers said. Using Nasa's infrared Spitzer Space Telescope, Massachusetts Institute of Technology (MIT) skygazers detected a telltale disk of what could be early planetary debris encircling a pulsar, as the remnants of a supernova are called. The cloud of gas and particles, which orbits the pulsar at 1.6 million kilometres, may eventually stick together by gravitational force to form a planet that could be the size of the Earth, the astronomers suggested.