The name of Clyde Tombaugh, discoverer of Pluto, is a step closer to being formally affixed to the planet’s most recognizable feature, a heart-shaped region that was informally called “Tombaugh regio” when the New Horizons spacecraft sent back the first pictures of the planet in July 2015.

The International Astronomical Union has approved the naming strategy devised by the NASA space mission’s operators, clearing the way for Tombaugh, Percival Lowell, the UA’s Michael Drake and a host of science-fiction creators and characters to be honored with their names on features of Pluto or its moon Charon — including characters from “Star Wars,” “Star Trek” and Sigourney Weaver’s “Ripley” character from the “Alien” movies.

The union, the same body that stripped Pluto of its planetary status in 2006, announced in a news release Thursday that it had approved the “naming themes” for Pluto and Charon.

In addition to names associated with mythology (Pluto is the Roman god of the underworld), the union said it would consider the names of “scientists and engineers associated with Pluto and the Kuiper Belt, pioneering space missions and spacecraft, and historic pioneers who crossed new horizons in the exploration of the Earth, sea and sky.”

That clears the way for Tombaugh to be honored with a “regio” or region of Pluto, along with Percival Lowell, who established the Flagstaff observatory from which Tombaugh found the planet in 1930.

The late Michael Drake, former head of the University of Arizona’s Lunar and Planetary Lab, who chaired the committee that approved the New Horizons mission, has a crater tentatively named for him.

The IAU approved honoring authors, artists and fictional space explorers on Charon. Craters, chasms, regions and mountains on Charon had been informally named for characters in science fiction books and movies.

“Star Wars” names include Leia, Skywalker and Vader, while “Star Trek” is represented by Spock, Kirk, Sulu and Uhura — all located in Vulcan Planum.

Film director Stanley Kubrick and novelist Arthur C. Clarke, both of “2001: A Space Odyssey” fame, are also named.

Back on Pluto, there is a crater named for Venetia Burney, who suggested the name for the planet shortly after it was discovered. She was 11 at the time.

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Honored space missions include the Columbia and Challenger shuttles, Pioneer, Voyager and the Soviet Sputnik satellite.

Terrestrial explorers include Leif Erikson and Sir Edmund Hillary.

Maps of the features and their names are posted on the New Horizons “Our Pluto” page at ourpluto.org

The names are not yet official. After the mission formally submits them, they need approval from the IAU’s Working Group for Planetary System Nomenclature.

Alan Stern, who led the New Horizons mission and who waged a very public spat with the IAU over its demotion of Pluto, praised the action.

“I’m very happy with both the process and partnership that New Horizons and the IAU undertook that led to wonderful, inspiring, and engaging naming themes for surface features on Pluto and its moons,” Stern said in a news release.

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