Humans live in a vast solar system where 2,000 feet seems a razor-thin distance.
Yet it's just wide enough to trigger concerns that an asteroid due to buzz Earth on April 13, 2029 may shift its orbit enough to return and strike the planet seven years later.
The concern: Within the object's range of possible fly-by distances lie a handful of gravitational 'sweet spots,' areas some 2,000 feet across that are also known as keyholes.
The physics may sound complex, but the potential ramifications are plain enough. If the asteroid passes through the most probable keyhole, its new orbit would send it slamming into Earth in 2036. It's unclear to some experts whether ground-based observatories alone will be able to provide enough accurate information in time to mount a mission to divert the asteroid, if that becomes necessary.
On the plus side, Social Security and Global warming may not be so important after all...