2004 FY31 (Potentially
hazardous asteroid passing by Earth)
Discovered on 31 March 2004 by Brian Skiff using the 0.59-m
Schmidt at Lowell Observatory as part of the LONEOS survey, it was already mag +18, at a high northern
declination and predicted to pass Earth less than two weeks later at
12.1 times the distance of the Moon (12.1 LD).
The images above were obtained during the object's approach to Earth
and show its change of direction and motion over a period of a week as
it approached the North Celestial Pole, then travelled rapidly South
East towards the Summer Milky Way.
Each frame in the animation consists of 15 images stacked together.
Those taken at the start have a longer exposure than those taken when
nearer the Earth, the exposure length chosen to keep the asteroid's
image from trailing. The length of the star trails therefore does not
properly reflect the increasing speed of motion.
The same frames used in the animation are shown below, together with
the track of the asteroid during the same period as a