In 1939, Harold Spencer Jones, our tenth Astronomer Royal wrote a paper titled: Is there life in other worlds? Spencer Jones was not only well regarded and honoured by his peers, he was also a great populariser of astronomy. So it is perhaps no surprise that in 1940, he published a popular book under the title: Life on other worlds. It gives 'a balanced popular survey of current astronomical knowledge and speculation' at that time and was described by the novelist HG Wells as a 'charmingly lucid book'.

So what did Spencer Jones have to say in his chapter Mars - the planet of spent life? He started with some of the practicalities of observing Mars and obtaining images, before going on to look at the work of Schiaparelli and the later work of Lowell. Schiaparelli was the first to observe the so called Martian Canals, whilst it was Lowell who worked up the theory that they had been created by intelligent life. Discarding the evidence on which Lowell based his conclusions, Spencer Jones went on to say that 'it is almost certain that there is some sort of vegetation on Mars'. Spencer Jones' popular books all went through many editions. If you are one of those who likes to browse through a physical rather than an electronic book, there are cheap second-hand copies available on the internet.