The NEAR Shoemaker spacecraft made history once again today when it brushed over the "toe" end of Eros, less than two miles (2.74 kilometers) from its surface, at 5:41 a.m. EST (ground receive time). The daring pass-the closest any spacecraft has come to an asteroid-marked the conclusion of a 4-day series of low-altitude flyovers that is returning extraordinarily detailed images of the asteroid's surface.

The low pass sequence ended this afternoon at 1:22 p.m. EST (ground receive time), when a 3.8-second burst from the spacecraft's 5-pound thrusters pulled it away from its breathtaking vantage point, and back toward an orbit 22 miles (35 kilometers) above the asteroid. There it will remain circling Eros until a maneuver on Feb. 12 pulls the spacecraft out of orbit and into position for its descent to the asteroid. Several more engine burns will slow NEAR Shoemaker's descent, allowing it to settle on to the asteroid's surface at about 3 p.m. EST.

Fame is fleeting in the rapidly growing realm of Kuiper Belt objects (KBOs). Last March astronomers spotted 2000 EB173, which has an estimated diameter of 600 kilometers. But that object quickly lost its distinction as the year's largest discovery. On November 28th Robert S. McMillan and later Jeffrey A. Larsen found a 20th-magnitude blip designated 2000 WR106. Initially its size was uncertain, and for a while observers believed it might exceed the diameter of 1 Ceres, the largest asteroid (933 km), or even Pluto's moon, Charon (1,250 km).

Gauging the diameter of 2000 WR106 accurately required firmer estimates for its distance and the reflectivity of its surface. Fortunately, German amateur astronomers Andre Knoefel and Reiner Stoss identified the object on photographic plates taken in 1955 with the 48-inch Schmidt telescope on Palomar Mountain. Those positions proved crucial in clinching an orbit with a mean distance of 43 astronomical units (6.4 billion km) from the Sun, an eccentricity of 0.06, and an inclination of 17 deg.

Clues to the diameter of 2000 WR106 came on December 30th, when David C. Jewitt and Herve Aussel (University of Hawaii) used the James Clerk Maxwell Telescope on Mauna Kea to measure its brightness at a wavelength of 350 microns. Combining this data with the object's visual and near-infrared brightness yielded a very dark albedo of 7 percent (so its surface is unlikely to have a widespread coating of frost). The diameter lies somewhere between 750 and 1,000 km -- most likely near 900. Thus 2000 WR106 does indeed challenge Ceres for the title of "largest known minor planet."

On the first night of 1801, Giuseppe Piazzi saw a "star" that didn't belong in the field of his little refractor mounted atop the royal palace at Palermo, Italy. "I have announced this star as a comet," he wrote later that January, "but . . . it has occurred to me several times that it might be something better." He had, in fact, spotted the first minor planet, which was soon named Ceres, after the Roman goddess of the harvest and the patron goddess of Sicily.

Exactly 200 years later, an eclectic mix of astronomers, artisans, philosophers, and historians gathered in Palermo to celebrate the Theatine monk's discovery. In a lecture prior to the group's party to mark the beginning of the new, true millennium, Giorgia Fodera-Serio pointed out that Piazzi's then state-of-the-art telescope has now been completely restored. All its parts are original, except for the eyepiece, and it has been remounted atop the former palace.

At the time, Piazzi's discovery seemed to be the long-sought confirmation of what today is known as the Titius-Bode "law." First publicized in 1772, it neatly described the orbital spacings of the five planets then known. But there was one glaring glitch: the law predicted a planet between Mars and Jupiter, but none was known. Ceres seemed to fulfill the law's prophesy.

After the newcomer passed through the Sun's glare and emerged once again into the night sky, it was recovered by Franz von Zach the night preceding the first anniversary of its discovery. Three months later, Heinrich Olbers discovered the second minor planet, Pallas. That posed a serious problem for the Titius-Bode law -- now there were two planets where only one should be. But by then Piazzi and others had already begun to doubt that Ceres measured up to full-planet status. Even to these early observers, it was evident that Ceres was too small to qualify. Today we know that this largest minor planet is only about 930 kilometers in diameter, a quarter the size of the Moon. And we know that Ceres is accompanied by thousands of similar bodies that inhabit the so-called asteroid belt.