The swarm of objects beyond Neptune known as the Kuiper Belt just keeps getting curiouser and curiouser. Last December, while checking up on 1998 WW31, an object that had been discovered out there two years earlier, Christian Veillet and two colleagues realized that it sometimes appeared elongated while other times as a double blip. News of the binary's discovery was announced this week on IAU Circular 7610.

Veillet's team recorded 1998 WW31 with the 3.6-meter Canada-France-Hawaii Telescope in Hawaii and the facility's new 100-megapixel camera. Even so, at 23rd magnitude and 6.9 billion kilometers away, 1998 WW31 did not divulge much about itself. Fortunately, a series of observations taken nearly a year earlier also showed doubling and elongation, clinching its status as a binary. Veillet says the two components orbit at least 40,000 km apart, and that one is about 0.4 magnitude brighter than the other. This would make the bodies roughly 150 and 200 km across.

More than just dust was kicked up when NASA's Near Earth Asteroid Rendezvous spacecraft, NEAR Shoemaker, made a successful landing on asteroid 433 Eros on Feb. 12. Also disturbed were the memories of an experiment carried out more than three decades ago by a student of Thomas Gold, professor emeritus of astronomy at Cornell University.

Images of small craters on 22-mile-long Eros, sent back to Earth by the NEAR spacecraft's camera, revealed a fine-grain material that has somehow found its way to the bottom of the craters. The members of the NEAR imaging team, including the team's leader, Cornell astronomer Joseph Veverka, expressed puzzlement over the movement of the dust that had created flat, smooth floors in craters. There is, they said, some unknown mechanism that moves the dust around so that it slides down the craters' sides, "ponding" in the bottoms.

Gold was, perhaps, the only observer not surprised. Static electricity, he argues, causes dust grains to levitate downhill into the bottom of craters -- the same process, he believes, that has filled craters on the moon. "If you added a layer 1 micron [0.001 millimeters] thick in the time since the Pyramids were built [about 5,000 years ago], you could get a layer 1 kilometer in depth over a billion years," says Gold, who has long been known as one of the world's foremost cosmologists.

"The features on Eros are so similar to those on the moon, that dust levitation has now to be reconsidered for all large lunar features, and major conclusions of lunar research now have to be reconsidered," says Gold.

Electric charges on the grains, he says, were created by charged-particle bombardment from the sun's solar wind, a current of ionized atoms and particles such as electrons and protons that the sun spews from its surface. When electrons with a high enough energy hit the dust grains, they either cause the grains to gain more negative charge or more positive charge, depending on the substance. "It's a very intriguing possibility and one which we will be evaluating seriously during the coming months," says Veverka, who is chair of Cornell's astronomy department.

Gold's controversial theory dates back to stormy debates that continued through the 1950s into the early 1970s on the geology of the moon's impact craters and their flat, dust-filled floors. Gold himself had written his first paper on the subject in 1955. And in the late 1960s his graduate student, the late Gregory J. Williams, carried out research at Cornell's astronomy department, which Gold chaired from 1959 to 1968, into the electrostatic agitation of the surface layers of fine rock powders. In 1976, Williams' Ph.D. dissertation, Electrodynamics and the Moon -- Transport Mechanisms, expounded many of Gold's theories on the transportation of dust on the moon.

The laboratory experiments found that dust particles under lunar conditions move when different grains adopt very different charges. The electrical interaction sets up strong electric fields on a very small scale, allowing electrical forces to levitate and move the dust particles.

"Based on the details of reflection of sunlight, grains on the surface had to be small enough so they could pile on top of each other in a very loose formation, which my colleagues called 'fairy castle structures.' I can't understand any process that could occur on the moon that would lift up material the size of a brick, but I can understand processes that would lift up 50-micron-sized grains," says Gold.

This contradicted the view of many geologists, who believed that lunar craters typically were filled either by material ejected by meteoroid and asteroid impacts or by lava. However, says Gold, the smoothing and filling in of craters on the moon and asteroid Eros was not accomplished by falling debris from an impact (which would give a "snowed over" appearance to the land and rocks) -- and lava flows on tiny Eros are not possible.

"The amount of material that is missing from the craters on the side of the moon visible from Earth, if distributed all over that area, would make a layer between one and two kilometers deep. You either have to say that this material vanished from the moon, which is not likely, or that it had migrated downhill just as it would have done on Earth for different reasons," says Gold.

The filling in of craters from dust levitation on Eros appears to Gold to be similar in nature -- and to be taking place at about the same rate -- to the erosion present on the hidden side of the moon, which does not receive as intense an electron bombardment from the solar wind as does the side facing Earth. Since Eros lies 289 million miles from the sun, it is hit by fewer higher energy electrons than the facing side of the moon.

To Marc W. Buie (Lowell Observatory), 2000 CR105 was at first just another distant discovery among dozens found during his team's ongoing search for trans-Neptunian objects using 4-meter telescopes in Arizona and Chile. But its uniqueness became apparent when dynamicist Brian G. Marsden started cranking out possible orbits for this 24th-magnitude find. "It was obviously far away, 53 to 55 astronomical units," Marsden recalls, well beyond most objects known to inhabit the Kuiper Belt.

In the months that followed, an international team led by Brett Gladman (Nice Observatory) quietly tracked the dim interloper. Thanks to their year-long pursuit, it's now clear that 2000 CR105 has a highly eccentric orbit that stretches out to roughly 400 a.u. -- more than 10 times Pluto's mean distance from the Sun and far larger than that of any known Kuiper Belt object. But more puzzling to dynamicists is the orbit's perihelion distance. At 44.5 a.u. (6.7 billion km), it is well beyond the perturbing influence of Neptune, whose gravity has flung countless other bodies out to the solar system's most distant fringes. So how did 2000 CR105 end up stranded out there?

Gladman and six colleagues offer several possibilities in an article submitted to the journal Icarus and summarized here. According to coauthor Matthew Holman (Harvard-Smithsonian Center for Astrophysics), the orbit of 2000 CR105 is dynamically chaotic and may simply be the consequence of eons of erratic drift. But that's a statistical long shot, so the team has explored other ideas. Perhaps the Kuiper Belt formed with numerous planet-size bodies in its midst, which wreaked orbital havoc before themselves being heaved out of the region. Or Neptune itself may have ventured farther out before settling into its present orbit. And though the notion is highly speculative, a massive perturber may yet await discovery beyond the Kuiper Belt's known boundary. Holman notes that a body the size of Mars 200 a.u. away could easily have escaped detection to date.

Resolving this mystery will take time, but one implication is already clear. Objects like 2000 CR105 should be exceedingly rare, so if others are found then the Kuiper Belt is likely much more massive than currently envisioned.