Free Republic

Earth has officially been joined in its orbit around the Sun by a new trojan asteroid. Named 2020 XL5, this chunk of rock is only the second object of its type ever to have been conclusively identified. Its discovery suggests that perhaps Earth trojans may be more common than we knew, and offers new insights into these mysterious rocks. Like the first trojan, astronomers predict that 2020 XL5 will hang around for at least 4,000 years before zipping off to parts elsewhere. "The discovery of a second Earth trojan asteroid may enhance our knowledge of the dynamics of this elusive...

While asteroids residing in the inner solar system will pass quickly through such small fields, trans-Neptunian objects (TNOs) orbit the Sun much more slowly. For example, Pluto, at an approximate distance of 40 A.U. from the Sun, along with the object Eris, presently the largest of the TNOs, has an apparent motion of about 27 arc seconds per day – although for a half year, the Earth’s orbital motion slows and retrogrades Pluto’s apparent motion. The 27 arc seconds is approximately 1/60th the width of a full Moon. So, from one night to the next, TNOs can travel as much...