James D. Livingston

The evolution of life

Matt Damon in "The Martian"

Pluto's surface as seen by New Horizons

SpaceX's Falcon 9 rocket

Size comprison of the Earth, the moon, and Pluto (lower left)

Aerial view of Spaceship Two crash in Mohave Desert

Close-up of nucleus of comet 67P taken by ESA spacecraft Rosetta

Wernher Von Braun & engines of Saturn V

Steven Swanson (left) and Russian colleagues

Yutu, Chinese rover, on the moon

Comet ISON and its green tail

International Space Station, where NASA will continue to support the astronauts during the shutdown

Artist's version of Mars One colony (Bryan Versteeg)

Kepler Space Telescope (artist's version)

Pluto - the Former Ninth Planet

Virgin Galactic space plane over New Mexico's Spaceport America

Saturn - Lord of the Rings

Arizona's Meteor Crater

Radar view of the surface of Venus as seen by Magellan orbiter

Use of Terra, a spin-off of CheMin (instrument on Curiosity), in King Tut's tomb

Streambed found on Mars by Curiosity (compared to dry streambed on Earth)

Self-portrait of the rover Curiosity on Mars.


Poor Little Pluto

July 9, 2013

Tags: Pluto, Hayden Planetarium, definition of planet, Clyde Tombaugh, International Astronomical Union, New Horizons, Eris

Published in The Patriot Ledger April 13, 2013:

My Very Excellent Mother Just Served Us Nine Pizzas. That was never literally true in my case, but when I was young, that mnemonic helped us remember the sequence of the planets – Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. What do we do now that Pluto is no longer officially a planet? Does my mother just serve us Nachos, or perhaps Nothing?

Some date the downfall of Pluto to 2000, when New York’s redesigned Hayden Planetarium featured models of the four inner or terrestrial planets and the four outer “gas giant” planets, but omitted Pluto. Visiting children, who had been taught the nine planets in school, often asked, “Where’s Pluto?” That soon led to a front-page New York Times article headed, “Pluto’s Not a Planet? Only in New York.”

The planetarium was soon deluged with hate mail from angry schoolchildren, many of who loved Pluto in part because they associated it with Disney’s loveable cartoon canine of that name (although the planet was actually named after the Greek god of the underworld, far less loveable). “Pluto is my faveret planet,” wrote one third-grader, “You are going to have to take all of the books away and change them. Pluto is a planet!!!”

Pluto is small, with a diameter of only about 1500 miles, less than half the diameter of Mercury and even smaller than our moon and several other moons of the solar system. Many of the third graders suspected that the downgrading of Pluto was simply a case of size discrimination, a common bias with which they were personally familiar.

The term “planet” is derived from the Greek word for “wanderer,” since the planets move around the sky among the fixed stars. The first six planets were known to the ancients, and are visible to the naked eye, the Earth by looking down, the others by looking up. Uranus, the seventh planet, was first observed by telescope by William Herschel in 1781, Neptune, the eighth, by Johann Galle in 1846. Irregularities in the motion of Neptune suggested the possibility of another planet farther from the sun, and after years of search for this “planet X,” Pluto was finally discovered by Clyde Tombaugh in 1930.

In January 2006, NASA launched the New Horizons spacecraft to explore Pluto and its moons. Only seven months later, the International Astronomical Union met in Prague and voted to approve the first formal definition of a planet, a definition that officially demoted Pluto, supporting the stance taken six years earlier by the Hayden Planetarium.

To be a planet, the IAU ruled, an object must (1) orbit the sun, (2) be massive enough for gravity to make it spherical, and (3) have cleared the neighborhood around its orbit. It was the third rule that killed Pluto. By 2006, hundreds of other objects had been found orbiting the sun out in Pluto’s neighborhood. Most are smaller than Pluto, but one discovered in 2005, called Eris, is more massive than Pluto. Rather than call Eris the tenth planet, the IAU classifies it and Pluto as dwarf planets and trans-Neptunian objects, i.e., objects beyond the orbit of Neptune.

Meanwhile, the robotic spacecraft New Horizons continues its multi-billion-mile journey to the cold outer reaches of the solar system, and is expected to reach poor little Pluto in July 2015. To me, and to all those former third-graders, Pluto’s still the ninth planet. And I still prefer nine pizzas to nachos or nothing.

Selected Works

A brief sequel to Arsenic and Clam Chowder, in which Mary Alice travels north on the Klondike Gold Rush
A sensational murder trial set in 1890s New York
Popular Science
The first review of the many and varied forms of magnetic levitation written for a general audience.
A entertaining treatment of the history, legends, science, and technology of magnets for a general audience.
Historical Biography
The dramatic life story of an early feminist and abolitionist who was both witty and wise.
Undergraduate Textbook
A lively introduction to the electrical, optical, and magnetic properties of solids.

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