The Atomic Energy Act of 1946
President Truman signs the Atomic Energy Act into law, laying the groundwork for both future military development of nuclear weapons and a civilian nuclear energy industry, though the latter will take time (and further amendments to the law) to develop. The primary development of the initial version of the law is the founding of the U.S. Atomic Energy Commission, a civilian agency intended to lead both areas of development (and intended to take over from the scientists who, up until now, had been operating in secret as part of the Manhattan Project). Over time, the Commission’s responsibilities will grow to include regulation, safety, and disposal of dangerous radioactive material. Major amendments will be made in 1954 under President Eisenhower to encourage the peacetime nuclear power industry to grow.
The 42nd episode of ABC’s science fiction anthology series, Tales Of Tomorrow, airs on ABC, with each episode’s opening titles proclaiming that the series is produced “in cooperation with the Science-Fiction League of America”, a collective of sci-fi writers including Isaac Asimov and Theodore Sturgeon among its members. This episode is missing from the archives and may be lost.
The BBC airs the 
The 36th episode of Doctor Who airs on the BBC. This is part six of the story now collectively known as 
Though every episode of the series to date has been flagged for indefinite retention due to its popularity in foreign markets, for the first time, the BBC archive issues instructions to erase most of the first three seasons of Doctor Who. This covers every episode from An Unearthly Child through the final episode of The Gunfighters, and it is at this point that many complete stories are lost forever in video form (such as Marco Polo and The Massacre), and huge swaths of the series’ run are erased as well (much of the 12-part epic The Daleks’ Master Plan). The series thus far has been produced in 405 line PAL videotape, and a new 625 line standard will become the default recording/transmission option in 1968. Many of the erased episodes are recovered years later from the foreign markets to which they were sold, from Africa to the Middle East, but many are never seen again.
NASA’s final Lunar Orbiter satellite is sent to the moon, with a goal of completing the mapping of the moon’s surface left unfinished by mechanical issues with its predecessor. Lunar Orbiter 5 completes the mapping of the lunar far side and helps engineers and scientists determine signal coverage from the Earth-based tracking stations that will help NASA stay in contact with future Apollo missions to the moon.
Atari releases the arcade game 
Cinematronics’ vector graphics arcade wargame 
MTV (Music Television), a New York City-based cable channel, goes on the air at one minute after midnight, premiering with the Buggles’ music video “Video Killed The Radio Star”. This heralds the beginning of the dominance of music videos in the music industry, though at first MTV’s format is to concentrate heavily on mainstream rock, new wave and semi-obscure acts (
ITV airs the 66th episode of the anthology series Tales Of The Unexpected. Edward Albert and Terry O’Quinn (Lost) guest star.
From within 500 million miles, cameras aboard NASA’s Voyager 2 unmanned space probe can now get a better look at planet Neptune than is possible with ground-based telescopes on Earth – even though, at present, that means a tiny disk only eight pixels across in images measuring 800 x 800 pixels. Voyager 2 is still over a year away from its closest encounter with Neptune, and even its own best photos don’t reveal any detail in the blue-green planet’s atmosphere. What is known is that, despite receiving less than half the sunlight and heat of the next innermost planet, Uranus, Neptune maintains the same temperature as Uranus. This means that Neptune is generating more heat than it receives from the sun.
The Soviet Union launches Soyuz TM-10, carrying cosmonauts Gennadi Manakov and Gennady Strekalov to space station Mir for a long-duration stay in orbit. After a 130-day stay aboard Mir, the TM-10 crew returns, bringing with them Japanese TV reporter Toyohiro Akiyama, who would arrive aboard Mir via Soyuz TM-11 in December. Strekalov will return to serve another tour aboard Mir in the 1990s, becoming the first Russian cosmonaut to arrive in a Soyuz and return home in an American space shuttle.
Baen Books publishes the seventh novel in the Honor Harrington series, “
Pay cable channel Showtime premieres the 
Running Press publishes John Sellers’ non-fictional recap of the video game industry’s early landmark titles, “
Sci-Fi Channel airs the third episode of the quirky modern-day science fiction series Eureka, starring Colin Ferguson, Salli Richardson, Debrah Farentino, Joe Morton, and Matt Frewer. (In the UK and elsewhere, this series is retitled A Town Called Eureka.) Tamlyn Tomita (Babylon 5, Star Trek: Picard) guest stars.
Syfy airs the 57th episode of the science fiction series Eureka, starring Colin Ferguson, Salli Richardson-Whitfield, and Joe Morton. Wil Wheaton (Star Trek: The Next Generation), Debrah Farentino (Earth 2), Felicia Day (Mystery Science Theater 3000), and Tembi Locke (Sliders) guest star.