An asteroid nine times the size of a cruise ship is dropping by Earth on Friday, and it's not coming alone. Asteroid 1998 QE2 will be about 3.6 million miles from our planet at its closest approach. And its proximity has already given scientists a surprise: It has its own moon, measured at about 2,000 feet wide.

The fly-by will mark the closest the asteroid comes to Earth for at least the next 200 years, according to researchers at who led the radar observations that spotted the asteroid's moon. The point of maximum proximity will come at 4:59 p.m. ET, or 20:59 UTC, Friday, according to the space agency.

"In the near-Earth population, about 16 percent of asteroids that are about 655 feet (200 meters) or larger are binary or triple systems," according to NASA. "Radar images suggest that the main body, or primary, is approximately 1.7 miles (2.7 kilometers) in diameter and has a rotation period of less than four hours."

Unless you can access a powerful telescope, you won't be able to see the asteroid, much less its lunar tagalong — 1998 QE2 will pass no closer than 15 times the distance between the Earth and its moon. You can watch live video of the asteroid's passage at , where a webcast will feature video from the Slooh Space Telescope and the Virtual Telescope Project.

hosted a special video on the asteroid Thursday; the agency also recommends the hashtag for those wanting to share thoughts about the asteroid on Twitter.

For amateur astronomers, NASA recommends trying to view the asteroid in the first week of June — particularly June 3 and 4 — when its sunlit side will face the Earth. As for the appearance of 1998 QE2, NASA says it reflects only 6 percent of the light that hits it, making it blacker than coal.

from: http://www.npr.org/blogs/thetwo-way/2013/05/31/18 7496903/huge-asteroid-makes-its-closest-pass-to-e arth-today