The Essential Role of Space Astronomy

Abstract.

It is a great honour for me to be here, addressing some of the most talented and renowned astronomers of this century on the occasion of his 70th birthday. Referring to Lo Woltjer, age has no meaning. It is another honour to be the last to speak among so famous people and to close what has been a fascinating symposium. My task is not made easier by the title of this paper which sounds a little strange to celebrate the former Director General of one of the most prestigious Earth-bound astronomical observatories. However, the deep involvement and pioneering contribution of Lo Woltjer in the interpretation of the X-ray background, renders my talk a little easier.