Mark Twain and Halley's Comet will share honors on a 36-cent aerogramme to be issued Dec. 4 by the United States Postal Service. The aerogramme commemorates the 150th anniversary of the birth of Samuel Langhorne Clemens, who adopted the pseudonym Mark Twain. It will have its first day of issue in his hometown, Hannibal, Mo.

Mark Twain's 1835 birth came in the same year as an appearance of Halley's Comet. He died in the year of its next appearance, 1910. Because of these coincidental events, the Postal Service decided to note the reappearance of the comet on the Mark Twain aerogramme. Although Mark Twain was born in the small village of Florida, Mo., he moved to Hannibal at the age of 4. The memories of his childhood on the banks of the Mississippi influenced his two best-known novels, ''The Adventures of Tom Sawyer'' and ''The Adventures of Huckleberry Finn.'' Issuance of the aerogramme also celebrates the centennial of the publication of the latter work.

Samuel Clemens adopted his pseudonym while working as a newspaper reporter, taking the name from the term meaning ''two fathoms deep,'' the minimum depth required for a riverboat's safe passage. During his career he also used the pen names ''Sergeant Fathom,'' ''Thomas Jefferson Snodgrass'' and ''W. Epaminandos Adrastus Blab.'' In addition to his novels, Mark Twain also is remembered for his skills as a riverboat pilot, travel writer and popular humorist and lecturer.

He is quoted as having said in 1909 that he expected to die the following year, noting ''The Almighty has said, no doubt, 'Now here are these two unaccountable freaks; they came in together, they must go out together.'' His prediction came true, but he could not have realized that his fame would continue into the next appearance of the comet, not to mention its future visits.