Asteroid 2012 XE54 captured on December 11 by Remanzacco Observatory (Credits: Ernesto Guido, Nick Howes).
On the morning of December 11, asteroid 2012 XE54 – discovered just two days prior – passed within 230,000 km of Earth. The 36 m long asteroid passed well within the Moon’s orbit, experiencing an unusual surface eclipse as it passed through Earth’s shadow.
2012 XE54 highlights the need for improved cataloguing of potentially hazardous asteroids. Tuesday’s passage was quite close in astronomical terms and an object of that size could easily have caused significant damage if it impacted on the planet. The asteroid that exploded above Siberia’s Podkamennaya Tunguska River in 1908 destroying 2000 square kilometers of forest is thought to have been about the same size.
As an encore, asteroid 4179 Toutatis will make its closest approach to Earth on December 12. This 5 km long asteroid has been identified for some time. It was first discovered in 1934 but was promptly lost and not discovered again until 1989. The asteroid, which is in 1:4 orbital resonance with Earth, will pass within 18 lunar distances from the planet. In early January, the Chinese lunar probe Chang’e 2 is expected to fly by the body, hoping to catch some images from within 1000 km.
View of 4179 Toutatis on December 11 from Slooh Observatory:
![A trajectory analysis that used a computational fluid dynamics approach to determine the likely position and velocity histories of the foam (Credits: NASA Ref [1] p61).](http://www.spacesafetymagazine.com/wp-content/uploads/2014/05/fluid-dynamics-trajectory-analysis-50x50.jpg)
“2012 XE54 highlights the need for improved cataloguing of potentially hazardous asteroids. Tuesday’s passage was quite close in astronomical terms and an object of that size could easily have caused significant damage if it impacted on the planet. ”
Yes, but the object was discovered and is now catalogued.
Objects of this size would even be difficult to detect even for space-based systems. About 30 meters in size, its orbit takes it out to over 3 AU, where it would be very faint even for the largest ground based telescopes. Our best efforts must remain focused on the largest objects that can cause regional damage. Tunguska-like small bodies like this one are for the time being a fact of life (and death).
Ed