The Mayans have plans for the Earth this Friday—destroying it to be specific. Let’s pretend, however, that that forecast doesn’t hold up to close scrutiny and that against all odds, we wake up in one piece on Saturday morning. That will free us to turn our attention to another way the world could end—rogue asteroids or comets—and those doomsday scenarios actually have the attention of scientists. The incoming ordnance the researchers most fear are those known straightforwardly as Near Earth Objects (NEOs). The dinosaurs could tell you a thing or two about the danger of such free-flying rocks. Oh wait, they can’t.
Not any object we can see earns the Near Earth label. It has to be on track to enter the air space of our solar system, passing within 1.3 astronomical units (AU)—or 121 million miles—of the sun. (A single AU is 93 million miles—or the Earth-sun distance.) Going by that standard, NASA estimates that there are thousands of NEOs out there, though the ones that worry them the most are the ones that measure 1 kilometer (.62 mi.) across—not that a smaller rock couldn’t do a whole lot of damage. (See, again, the ex-dinosaurs.)
NASA, in cooperation with a global network of optical and radio telescopes, has been standing watch against space rocks for a while, thanks to its Near Earth Object Observations Program. Telescopes in Kitt Peak, Flagstaff and Tucson, Arizona; Goldstone, Calif; Okayama, Japan; Padua, Italy and elsewhere keep the skies constantly scanned, feeding what they find into a global database of any and all menacing bodies. So far, the telescopes have spotted nearly 850 asteroids that cross the 1 km threshold, and hope to have 90% of all of them catalogued within 10 years.
On Dec. 12, one of these bruisers, known as Toutatis, caught the eye—or antenna—of the Goldstone radio telescope. Today, NASA’s Jet Propulsion Laboratory (JPL) released a wonderfully eerie video clip of the rock as it makes its slow, rolling approach. Toutatis measures 3 mi. (4.8 km) across and rotates on its axis once every 5.4 days. It processes—or wobbles on its axis like a badly thrown football—once every 7.4 days.
But if the Earth is Toutatis’s target, it’s going to miss. The 64-frame video was taken when the asteroid was at two slightly different distances—both about 4.4 million miles (7 million km) from here. That, by way of comparison, is 18 times the distance to the moon. Ever since, it has been moving away and the gap has been growing.
Toutatis won’t be back until 2069, when it will make an admittedly closer—but still safely remote—approach of 1.8 million mi. (3 million km). NASA puts the odds of its striking us on any of its approaches over the next 400 years at precisely—and comfortingly—zero. Still, Toutatis has thousands of brothers and sisters out there, and any one of them could turn out to be the delinquent in the family. For that reason, the telescopes will never blink. We can all go about our business, assuming we’re safe—until, that is, we’re not.