The story begins with a comet that touches the Earth during flight and collects a few small pieces. About forty people of different nations and ages are doomed to a two-year journey through a comet. They form a mini-society and cope with the hostile environment of the comet (mainly with cold). The size of the "comet" is about 2,300 kilometers in diameter - much larger than any comet or asteroid that even exists.
Book Off On A Comet! A Journey Through Planetary Space (by Jules Verne)