Science Fiction Day is celebrated unofficially by many science fiction fans in the United States on January 2. The date was chosen (not known by whom and when) because it is the birthday of famous science fiction writer Isaac Asimov.
Isaac Asimov was born on January 2, 1920, to a Jewish family on the border between Russia and Belarus, and at the age of three emigrated with his family to the US. He is responsible for several great literary works such as "Sunset," "I, Robot," "The naked sun" And more.
SFD is not an official holiday of any kind (in the sense that it is not recognized or declared by a government or an organization), but it is, to a certain extent, a feature of television on the Hallmark channel.
If you want to mention the science fiction day, spend it by reading a good science fiction book or watching a science fiction film.
Recommended partial list:
Books by Philip K. Dick or Kurt Vonnegut, Stanley Kubrick's Movie Marathon, 2001: Space Odyssey, Ridley Scott, Alien, or Garth Jennings, The Hitchhiker's Guide to the Galaxy.
In "Alien" you will see one of the most famous footage of the science fiction scam of all time, in a section on how "in space no one can hear you scream" and how a close encounter of the third kind becomes a jaws nightmare when an alien invades a spaceship. The "Hitchhiker's Guide to the Galaxy" is a comic science fiction film based on Douglas Adams's book about what happens just seconds before the earth is destroyed by a foreign construction team and Arthur Dent and his friend Ford Perfect are rescued as they travel to the Golden Heart as trams in the galaxy.
If you like science fiction, this is the day to celebrate your love. If not, this is the day to meet.