Book written in 1954 by Eleanor Cameron, telling the tale of two boys who find a mysterious ad in a newspaper asking for two young boys to build a space ship. The two boys build a space ship quickly, out of old tin and scrap wood, and bring it to the advertiser, the mysterious Mr. Bass, a scientist living in an observatory who goes unnoticed by most of the townspeople for some reason. He shows the boys a previously undetected satellite of the earth, the eponymus planet, that can only be seen with a special filter he has concocted. He gives them some special fuel he invented to power their spaceship, and tells them to fly to the mushroom planet (after getting their parent's permission). He warns them that their trip will only be succesful if they bring a mascot.
When it is time for launch, they grab a hen at the last moment for a mascot, and rocket into space. They wake up on the mushroom planet, a small, verdent world covered in soft moss and tree size mushrooms. They quickly meet some residents of the mushroom planet, small men with large heads and slightly green skin, the cousins of the mysterious Mr. Bass. They tell the boys that their planet has had a crisis and everyone is slowly dying. The boys meet up with the king of the planet, the Great Ta, and end up solving the natives' problem, before returning to earth.
This book is very imaginative, especially considering the brief size and the vocabulary limitations of the audience it was written for. A small undetected satellite of the earth, covered with mushrooms and inhabited by spore people. The only problem is the fact that very little time is actually spent on the mushroom planet, and it is not described in as much detail as I would hope. This book was also written at the request of the author's son, and is (like Deltron 3030) a blend of science and magic. 1954 was a year when the idea of science and progress still reigned supreme, so the book focuses around the boy's spaceship. However, the book also has a very magical feel to it, in the person of the mysterious Mr. Bass, who in addition to being a spore person and a scientist is later (in the sequels) revealed to be both a galactic traveller and a magician, as well as a Welsh bard, and so on.