London, January 22 (ANI): Reports of a tiny asteroid buzzing by Earth recently has suggested that our planet is vulnerable to objects whose peculiar orbits put them in a game of hide-and-seek with us.
According to a report in New Scientist, an Earth-based telescope spotted the 10-metre space rock hurtling our way just three days before a near miss on January 13, when it flew by at just one-third of the distance to the moon.
The asteroid is never expected to hit Earth and would burn up before hitting the ground in any case.
But its unusual orbit seems ingeniously designed to evade the surveys by scientists on earth.
It is likely that a handful of objects large enough to cause harm are hiding under similar circumstances.
Large asteroids are relatively easy to spot because they reflect the most sunlight.
But smaller asteroids, which can still damage Earth if they span at least 30 to 50 metres, are usually too dim for telescopes to detect except during brief close approaches to Earth.
For a typical near-Earth asteroid, these occurrences are a few years or decades apart.
However, the unexpected visitor on January 13, called 2010 AL30, kept far enough from Earth to be invisible for more than a century.
The prolonged avoidance occurred because the period of its solar orbit was 366 days - very close to Earth's year.
Like a slightly slower race car that is periodically lapped by its competitor on a circular track, it stays far from Earth for long stretches.
"2010 AL30 may become a sort of 'poster child' for hiding asteroids," said Alan Harris of the Space Science Institute in Boulder, Colorado.
Similar "synchronized" asteroids may be hiding with periods of very close to two, three, four years and so on, according to Harris.
"Those with periods of about four years pose the greatest risk to Earth, because they would be in sync with both Earth and Jupiter," said Timothy Spahr of the Minor Planet Center in Cambridge, Massachusetts.
Such asteroids would be particularly influenced by Jupiter's gravity, which could nudge them onto a collision course with Earth. (ANI)