Less than a week after an intruder asteroid was found by astronomers using “defender” telescopes in Arizona and Hawaii, the world has a new potentially dangerous lump of rock to keep an eye on, and perhaps, one day, deal with before it burns a hole in a city.
The object called 2014RC will come within 40,000 kilometres of New Zealand at 6.18am local time this Monday.
It’s about 20 metres across, the same size as the Chelyabinsk meteorite, which injured 1491 people in the Russian city of the same name, over which it converted its kinetic energy into heat, light, and a deafening and structurally damaging shock wave at an altitude of around 90,000 feet during the morning peak hour of February 15, 2013.
Asteroid 2014RC will not result in anything like that spectacle, in which a section of that meteorite punched a hole in an ice-covered lake after the main air blast released the equivalent of 500 kilotonnes of high explosives, or about 30 times the energy unleashed by the Hiroshima and Nagasaki atomic bombs.
This newly discovered object is too high to be visible to the naked eye, unless it hits a fragment of orbital space junk. But it might be seen by amateur astronomers with reasonably powerful telescopes in Australia, over which the eastern sky will still be dark as 2014RC dips to its lowest point over NZ, just after local sunrise.
The real problem with 2014RC is that Earth is stuck with it and needs to remain vigilant, says NASA:
“While 2014 RC will not impact Earth, its orbit will bring it back to our planet’s neighbourhood in the future. The asteroid’s future motion will be closely monitored, but no future threatening Earth encounters have been identified.”
Computing the orbits of earth-crossing objects is a multi-body exercise including the gravitational influences of Mars, Venus and even Jupiter, as well as the perturbations caused by the Earth and its moon, and there are variable values for each that over a comparatively short period of time can produce markedly different results from those based on only a small number of observations.
2014RC doesn’t meet the internationally used metric of a diameter of 100 metres or more to be considered a potentially hazardous object to earth on a large scale. But neither did the estimated size (30-70 metres) of the Tunguska Meteorite of 1908, which would kill several million people had it struck this year, as there are now many cities found in that part of Siberia.
The world doesn’t yet have all the tools it needs to detect hazardous comets and asteroids. Tunguska, like Chelyabinsk, came from out of the direction of the sun. 2014RC was found against a dark sky, and it becomes the 1497th intruder known to science as an Earth-crossing object that will be on a watch list forever.