Synopsis

In the year 2003, Professor Tenma is distraught when his son Tobio is killed in a car accident. He loses himself in his latest project, creating Atom, a robot boy programmed to be forever good.

Upset that his Tobio-substitute can never grow up, Tenma sells Atom to Ham Egg, the cruel ringmaster of a robot circus. Atom meets the kindly Professor Ochanomizu, who adopts him, inspires him to become a crusader against evil, and eventually builds him a robot "sister," Uran.

(Source: The Anime Encyclopedia)

"Tetsuwan Atom was the first television anime series to air in a 30-minute programming slot. It was broadcast by Fuji Television and aired on Tuesdays when broadcast began in 1963. The first episode debuted on New Year's Day with a 27.4% viewership rating, with the series later peaking at over 40% rating by the following year. From 1964 onward, the airing was changed to Saturdays. When American television producer the late Fred Ladd helped NBC Enterprises adapt the series for broadcast in the United States in 1963, the title Astro Boy was used instead of the manga's English title Mighty Atom. The change was forced because of its similarity to the contemporary American superhero character Mighty Mouse, which Osamu Tezuka used as a basis for the character Atom."