on 9 January 2010
There were indeed some mysterious and as far as I am aware still unidentified 1920s and later radio signals.
This was one, if rather tortured, attempt to find some explanation for these signals by a reasonably reputable science writer. This book was really written at the beginning of the the space age and in the intervening years it has become obvious that there is no hibernatiing alien space probe in the Solar System.
This book originally rang some alarm bells in the scientific community and telescopes were swung on Epsilon Bootes. The original text books did give the distance of this star as about 250 light years. Using more modern methods this was updated to nearer 500 light years making it unlikely to be the source of the original signals.
Despite this the book is still an interesting example of the lengths that are still being taken to try and prove "that we are not alone".