A Pluto pilgrimage

The first thing you notice about the Lowell Observatory, the place where Pluto was discovered, is that the little guy gets top billing.

The road rises quickly from the city streets of Flagstaff, Ariz., up Mars Hill  and on to the entrance to the 115-year-old observatory's grounds. A pillar marks each side of the entryway. One pillar reads "Lowell Observatory," and the other pillar displays a column of nine runes that could have come from a chapter of Dan Brown's latest thriller, "The Lost Symbol."

These symbols stand for the solar system's worlds, and the symbol right on top is a combination of the letter P and L. That stands for Pluto, arguably the most controversial world in the solar system. It also stands for Percival Lowell, the observatory's founder - who was perhaps as controversial in his day as Pluto is today.

If any place on Earth should serve as a shrine to Percival Lowell and Pluto, it would be the 740 acres of forested grounds beyond the pillars. This is the place Lowell selected for his study of the "canals" he thought he saw on Mars. This is where he started the search for a "Planet X" that he was sure existed beyond the orbit of Neptune. This is where young astronomer Clyde Tombaugh followed up on Percival Lowell's predictions by poring through stacks of photographic plates. And this is where Tombaugh's painstaking effort paid off in 1930 with the discovery of Pluto.

It turns out, however, that the Lowell Observatory is about much more than the best-known dwarf planet.

For example, Vesto Slipher, the observatory director who presided over Pluto's discovery by Clyde Tombaugh in 1930, also came up with the telescope data that later led Edwin Hubble to conclude that the universe is expanding. Steele Wotkyns, Lowell's public relations manager, says that's one of the first things tourists are told.

"Of course we tell them about the discovery of Pluto, but we like to lead with that story about the expanding universe because it's a big one," he told me during my own tour of the place.

There are other big ones as well: Lowell's astronomers were in on one of the first direct observations of planets beyond our solar system. They've helped to chart clouds on Titan, arguably Saturn's most mysterious moon. They're part of the science team for New Horizons, NASA's mission to Pluto.

And that's just one side of the Lowell mission: The observatory is unusual in that it's also heavily engaged in public outreach. About 80,000 visitors come to the observatory's 740-acre spread every year, to see sights including the telescope involved in Pluto's discovery.

It was the Pluto connection that drew me to Lowell this week - not just because of the tourism angle, but also because the locale's history figures prominently in "The Case for Pluto," my newly published book about the controversy surrounding the whole idea of planethood.

For years now, astronomers and everyday people have been debating Pluto's proper place in the planetary scheme of things. Now that an array of Pluto-like worlds have been found on the edge of the solar system - including one that's bigger than Pluto - do all those things merit the "planet" label? It's my view that they do, but I wanted to see what Lowell's scientists thought.

It would be easy to enlist Lowell's scientists as the best defenders of the Plutonian faith - but that's not the case. Officially, Lowell's astronomers take no stand on whether the International Astronomical Union was correct when it voted to classify Pluto as a dwarf planet, yet a non-planet.

"I see it as an opportunity to talk about the process of science," Eileen Friel, the observatory's new director, told me. She said the debate over Pluto shows how new information can affect how scientists - and members of the general public - think about scientific concepts.

Just for fun, the observatory is conducting its own ballot on the issue. Donation boxes are set up in a row in the Rotunda, a 93-year-old exhibition space in the observatory's historic headquarters building. Visitors can register their "votes" on the planethood issue through their donations.

"At first, if you put something in the 'dwarf planet' box, people would give you this ugly glare," recalled Kevin Schindler, the observatory's outreach manager. As the controversy continued, the flow of donations ramped up to three times the normal rate, he said.

As of last month, $1,711.80 was tallied up in favor of calling Pluto a planet, compared with $640.05 for the "dwarf planet" label.

The Rotunda also houses a contraption called a "blink comparator," which Tombaugh used to compare photographic plates from the observatory's 13-inch Lawrence Abbott telescope, now known as the Pluto Discovery Telescope. Tombaugh spent thousands of eye-straining hours at the comparator, checking plates for the telltale signs of small objects in orbit. Even today, you can click-click-click between replicas of the original plates on which Pluto was found and try spotting the dwarf planet for yourself.

Schindler said Tombaugh's achievement stands as "a testament to patience and dedication."

"In today's world of attention deficit disorder, I don't think anybody could do this anymore," he said. Nowadays, computers sift through databases of images taken by computer-controlled cameras, alerting the humans only if they find something worth following up on. That's how Pluto's long-lost kin are being tracked down on the solar system's rim.

Many of the tourist stops on the Lowell Observatory's main grounds relate to its storied past: the 24-inch Clark telescope (which was installed in 1896 and is still used today for public viewing), Percival Lowell's mausoleum, the Pluto Discovery Telescope and the 350-foot-long planet walk that puts the distance between the sun and Pluto in perspective. (On that scale, the nearest star would be in Los Angeles, 464 miles away.)

To see Lowell's next landmark instrument, the Discovery Channel Telescope, you don't have to go as far as Los Angeles - but you would have to travel 40 miles southeast of Flagstaff, to a site known as Happy Jack. The telescope's 4.2-meter-wide (13.8-foot-wide) mirror is expected to reveal new frontiers in astronomy.

Friel said one of the telescope's first assignments will be to conduct an extended survey of the same region of outer space where Pluto was found. "It has direct relevance to the observatory's legacy," she said.

And so, almost 80 years after Tombaugh's discovery, the saga of Pluto and the Lowell Observatory is coming full circle.

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