2015 SO2 is an Aten asteroid that is a temporary horseshoe companion to the Earth, the ninth known Earth horseshoe librator. Prior to its most recent close encounter with the planet (2015 September 30) it was an Apollo asteroid.

Discovery

2015 SO2 was discovered on 21 September 2015 by B. Mikuž observing with the 0.6-m f/3.3 Cichocki telescope at the Črni Vrh Observatory in Slovenia. As of 30 November 2015, it has been observed 84 times with an observation arc of 9 days.

Orbit and orbital evolution

2015 SO2 is currently an Aten asteroid (Earth-crossing but with a period less than a year). Its semi-major axis (currently 0.999115AU) is similar to that of Earth (0.99957AU), but it has a relatively low eccentricity (0.108105) and moderate orbital inclination (9.181°). Gravitational interaction with Earth causes its orbit to change so that its average period is one year. It alternates between being an Aten asteroid and being an Apollo asteroid, changing dynamical status every 113 years approximately. As of 30 November 2015, this object is the 14th known Earth co-orbital and the 9th known object following a horseshoe path with respect to our planet. Its orbital evolution is characterized by alternating horseshoe and quasi-satellite episodes.

Physical properties

With an absolute magnitude of 23.9, it has a diameter in the range of 50–111meters (for an assumed albedo range of 0.04–0.20, respectively).

Relative to Sun and Earth

See also

Notes

  • ^ This is assuming an albedo of 0.20–0.04.

Further reading

  • Bottke, W. F., Jedicke, R., Morbidelli, A., Petit, J.-M., Gladman, B. 2000, Science, Vol. 288, Issue 5474, pp.2190–2194.
  • Christou, A. A. 2000, Icarus, Vol. 144, Issue 1, pp.1–20.
  • Bottke, W. F., Morbidelli, A., Jedicke, R., Petit, J.-M., Levison, H. F., Michel, P., Metcalfe, T. S. 2002, Icarus, Vol. 156, Issue 2, pp.399–433.
  • Brasser, R., Innanen, K. A., Connors, M., Veillet, C., Wiegert, P., Mikkola, S., Chodas, P. W. 2004, Icarus, Vol. 171, Issue 1, pp.102–109.
  • de la Fuente Marcos, C., de la Fuente Marcos, R. 2016, Astrophysics and Space Science, Vol. 361, Issue 1, article 16 (10 pp).

External links