An Amateur's Mercury Odyssey

Mercury from Mount Wilson and from Messenger
At left is a composite of 40 near-infrared images of Mercury taken in 1998 with a video camera attached to the 60-inch telescope on Mount Wilson (and, at center, as reprocessed in 2007). Compare them to the nearly identical — but much more detailed — view acquired last year by the Messenger spacecraft. Among the many features in common is the very bright spot above center.

Today amateurs routinely employ stacking — selecting and then combining the very sharpest images to yield the best possible detail. Programs like Registax do this almost automatically. But Dantowitz first had to digitize the analog video and then painstakingly find the best frames by hand. "Stacking" as we know it today hadn't been invented yet. The team called its technique "selective image reconstruction."

Fortunately, all that effort paid off. The resulting composite view showed never-before-seen details on a side of Mercury that had been totally missed during Mariner 10's flybys in the mid-1970s. Particularly intriguing was a very bright 100-mile-wide spot, located at 35°N, 300°W, that the team imagined to be some kind of impact feature. The three amateurs published a tidy article in the Astronomical Journal's May 2000 issue, and that should have been the end of the story.

But as the years went by, Dantowitz kept wondering about the nature of that bright feature. In 2008, knowing that NASA's Messenger spacecraft would soon reveal the true nature of his find — and the entire planet, for that matter — he petitioned the International Astronomical Union to have the bright spot named for American composer Aaron Copland. (The IAU names craters on Mercury after artists, musicians, painters, and authors.)

"Copland wrote Fanfare for the Common Man, one of the most recognizable pieces of 20th-century American classical works," Dantowitz noted in his petition. "This Mercury feature was discovered by using common, off-the-shelf commercial video equipment installed by an elementary-school science teacher doing research at a professional observatory. A true discovery that is a 'Fanfare for the Common Man'!"


Mercury from Messenger
The Messenger spacecraft captured this false-color view of Mercury during its third flyby of the planet on September 29, 2009. The bright spot seen from Earth doesn't look like other craters, and its origin remains unclear. The IAU has assigned the name Copland to the large basin just to the spot's east (arrowed). Click on the image for a larger view.

Last year Messenger did reveal an intriguing bright spot exactly where the Mount Wilson team had spotted it more than a decade earlier. But it's very strange — probably volcanic in origin — so the IAU's planetary moniker-makers and Dantowitz agreed to assign Copland to a true impact basin, 129 miles (208 km) across, adjacent to the mysterious white spot. The naming was announced last week on the Messenger website.

"I finally feel happy about the Mercury work!" Dantowitz exults. Revealing an unseen side of the planet, armed with $100 videocams and sheer determination, was a real triumph. "If only I had then the cameras and computers that I have now," he muses.