"The second effect is the turbulence of the atmosphere makes
things fainter," Tholen said. "We had to keep trying over and
over until we got one of those nights when the atmosphere was
calm." Tholen and the team also discovered the asteroid is
elongated, so that as it rotates, its brightness changes. That
was another challenge for the astronomers: Because they didn't
know the asteroid's rotation period, they didn't know when it
would wax and wane, and when it would grow too faint to see.
"This object was changing its brightness by a factor of three or
four -- it was just enormously variable," Tholen said. "It was
hit and miss depending on which night you observed it." Many
predicted the end of the world would come Friday, the day on
which a long phase in the ancient Mayan calendar came to an end.
Some believe the day actually comes Sunday. Modern-day Mayans
say the end of the calendar phase doesn't mean the end of the
world -- just the end of an era, and the start of a new one.