As the world marvels at the first-ever close-up images of Pluto beamed to Earth, it is a reminder of a sharp global division: those with nine-planet childhoods vs. those now growing up in a solar system defined by eight planets.
The clear, striking pictures of Pluto, with its surprising heart-shaped region, has pumped new energy into the cultural debate over its status. Is Pluto a planet, or something less?
Susan German, a 45-year-old science teacher in Hallsville, Mo., is excited to use the new Pluto images in her eighth-grade science classes but says she also feels a twinge of unease.
"I grew up with nine planets, and I memorized the order," German said. "In my heart, I feel like Pluto is a planet."
She is among millions of Americans across generations who learned the solar system with the planetary mnemonic so many still reference: My Very Educated Mother Just Served Us Nine Pizzas (working outward from the sun, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto).
"The parents of my students, they'll ask about this," German said. "They'll say: 'Hey, we were talking around the table, and my daughter told me Pluto is no longer a planet, and she tried to explain it to me. I'm just checking to make sure she got it right.'"
Astronomer Clyde Tombaugh discovered Pluto in 1930, the same year that Walt Disney created the cartoon dog of the same name. It was a full-fledged planet for 76 years, until 2006, when the International Astronomical Union voted on the definition of "planet." Pluto didn't make the cut.
To qualify as a planet, astronomers agreed that a body must orbit the sun, be roughly spherical and must "clear its neighborhood," which means it dominates its orbit, consuming smaller bodies, pushing them away or turning them into satellites. Pluto meets the first two conditions but not the last. It was bumped down to the rank of "dwarf planet."
Controversy about that vote still abounds, with Pluto lovers arguing that the icy object at the far end of the solar system deserves to be reinstated.
"It's more an emotional argument," said Michael Burstein, a science writer and former teacher who, along with his wife, Nomi Burstein, founded the Society for the Preservation of Pluto as a Planet, or SP3. "Up until now, Pluto was the only planet discovered by an American astronomer, the only planet discovered in the 20th century and generations have learned about nine planets. It seemed abrupt that we would downgrade it."
The stars, the moon and planets are among the first facts that small children learn about science, and their galactic images are emblazoned on lunchboxes and place mats in millions of American households.
Burstein, who works in educational publishing, said most school textbooks now refer to Pluto as a "dwarf planet" and that children born after 2006 learn it that way. But the Society for the Preservation of Pluto as a Planet has many young fans, he said. "Mostly kids write to say 'I support you, and Pluto should be a planet' and they include lots of exclamation points," he said.
Mike Mangiaracina, 43, who teaches science at Washington's Brent Elementary School, says the demotion of Pluto is a "golden opportunity" to demonstrate how science works.
"Here's this thing that adults had assumptions about, and we're forced to rethink it," said Mangiaracina, whose smartphone is loaded with two different apps for New Horizons, the NASA probe that flew by Pluto and is sending images back to Earth. "That's what science is: It's about challenging assumptions and not getting too comfortable with your own theories. It's the idea that nothing is carved in stone, that we can get the best idea we can about something, but it's always subject to change. Always."
In mid-July, children who gathered for a Smithsonian Associates summer camp offered various ideas about Pluto.
Eleanor DeCarmine, 6, of Arlington, Va., said anyone visiting Pluto must keep their helmets on "or their heads will freeze off" because of the icy exterior, estimated at 400 degrees below zero.
Khalil White, 61/2 and a budding astrophysicist who keeps the NASA website on his home computer in Falls Church, Va., said he always associated Pluto with the Disney character.
And Brooke Brown, 8, of New York reported that a female astronaut had proved Pluto to be a dwarf planet. "She flew up there and stayed a few days and got evidence," Brooke said matter-of-factly. "This happened in 1996." (No human has visited Pluto, which is about 3 billion miles from Earth.)
Just one of the 19 campers admitted to arriving at camp thinking Pluto was a planet, but she quickly learned otherwise.
At the planetarium at Rock Creek Park in Washington -- the only one the National Park Service operates -- Pluto remains a planet, at least on an outdated display of the solar system.
Ranger Tony Linforth, 46, fired up the projector and gave a presentation he has repeated weekly for years. He introduced planets, scaled to size with his red laser pointer. In addition to the solar system's "rocky worlds" and "gas giants," Linforth set aside time for a tiny speck on the dome above: "Oh, my gosh, I see something else up there!"
On cue, kids from around the room shouted, "Pluto!" "It's not a planet!" "It used to be a planet!"
"You guys weren't even alive yet," an adult commented loudly.
Linforth said he makes it a point to talk about Pluto despite its reclassification. "People are so attached to Pluto," he said. "They want to see it; they want to talk about it."
A few hours later, about 100 parents and children gathered in the field outside the planetarium to stargaze. Linforth urged them to enjoy the view and pay attention to the images coming from the New Horizons mission.
It was the first many had heard of the Pluto flyby.
Stephanie Williams, 37, said she remembered learning about Pluto as the smallest planet. Her 7-year-old son, Aaron, countered that Pluto no longer met the definition.
Others said they thought Pluto's status did not matter.
"Which one got kicked off?" asked Val Korostyshevskiy, 39, who came to see the stars with his 10-year-old daughter, Sofia. "To me, it's just exciting that we're able to send a probe" to the end of the solar system.
Family on 07/22/2015