Lucky Starr and the Big Sun of Mercury

From Wikipedia-- Lucky Starr and the Big Sun of Mercury is the fourth novel in the Lucky Starr series, six juvenile science fiction novels by Isaac Asimov that originally appeared under the pseudonym Paul French. The novel was first published by Doubleday & Company in March 1956. Since 1972, reprints have included a foreword by Asimov explaining that advancing knowledge of conditions on Mercury have rendered some of the novel's descriptions of that world inaccurate. Cover artist Darrell K. Sweet