NASA is about to begin detailed observations of an asteroid nearly twice as wide as Canada's largest stadiums, scheduled to pass between the Earth and the moon's orbit next Tuesday.

The 400-metre-wide space rock known as 2005 YU55 will make its closest approach to Earth at 6:28 p.m. ET on Nov. 8. At that point, it will be just 324,600 kilometres away from Earth or roughly 85 per cent of the distance between the Earth and the moon. The last time an asteroid this big came this close to Earth was in 1976.

This radar image of asteroid 2005 YU55 was generated from data taken in April of 2010 by the Arecibo Radar Telescope in Puerto Rico. (NASA/Cornell/Arecibo) However, it isn't expected to pose any threat and its gravity will have "no detectable effect on anything here on Earth," NASA reported.

Astronomers anticipate that the close encounter will allow them to bounce radio waves off it and get images of the asteroid as detailed as two metres per pixel. Those are expected to provide information about its surface features, shape, dimensions and other characteristics.

NASA was scheduled to begin its measurements using the Deep Space Network Antenna in Goldstone, Calif., at 12:30 p.m. ET Friday and to continue daily measurements until Nov. 10. Starting Nov. 8, radar observations of the asteroid will also be made using the Arecibo Planetary Radar Facility in Puerto Rico.

2005 YU55 regularly passes close to Earth, but hasn't come this close in 200 years.

NASA said amateur astronomers interested in looking at the asteroid will need a telescope with an aperture of 15 centimetres or larger.