Asteroid 2000 PH5: Earth's Annual Visitor

An asteroid approximately 120 meters in extent has been visiting Earth since 1999 and will continue to do so until 2006. During the 1999 through 2006 interval, asteroid 2000 PH5 made, or will make, an annual Earth approach in late July. It will make its closest approach to Earth this year (on July 25) and next year (July 26) to within 4.5 lunar distances, or about 1.1 million miles. There is no concern of any threat to Earth by this asteroid for at least two hundred years because its orbit is well-determined from both optical and radar observations. Asteroid 2000 PH5 was discovered on August 3, 2000 by the MIT Lincoln Laboratory's near-Earth Asteroid survey (LINEAR) just after the asteroid's close Earth approach in late July of that year. A so-called Aten asteroid, 2000 PH5 swings about the sun from just outside the orbit of Venus out to the region between the orbits of Earth and Mars. Because its orbital period is nearly equal to the Earth's one-year orbit about the sun, asteroid 2000 PH5 returns annually to the Earth's neighborhood in late July. However, since its orbital period is slightly less than that of the Earth, these annual visits to within 9.3 million miles will not continue beyond 2006.

For a look at the orbital characteristics of this asteroid, see here.