Is the Earth the only place in the Universe where life exists? Most astronomers think not. The evidence suggests that living beings may be commonplace on the planets of other stars
IN November 1974, scientists in the US broadcast a radio message. Its content was not very exciting: descriptions of the materials that make up living cells and of the human population of the Earth. What was unusual was its destination. The scientists did not send their broadcast in the direction of any listener on the Earth. They sent it towards a cluster of stars some 24 000 light…
