Comet Elenin started breaking up in August after being blasted by a huge solar storm, and a close pass by the sun on Sept. 10 apparently finished it off, astronomers say. So what will cruise within 22 million miles (35.4 million kilometers) of our planet Sunday is likely to be a stream of debris rather than a completely intact comet.
And the leftovers of Elenin won't return for 12,000 years, astronomers say.
"Folks are having trouble finding it, so I think it's probably dead and gone," said astronomer Don Yeomans of the Near-Earth Object Program Office at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
That means it probably won't present much of a skywatching show Sunday, scientists have said.
The doomsday comet
Elenin's apparent demise may come as a relief to some folks, since apocalyptic rumors circulating on the Internet portrayed the comet as a major threat to Earth.
One theory claimed Elenin would set off havoc on Earth after aligning with other heavenly bodies, spurring massive earthquakes and tsunamis. Another held that Elenin was not a comet at all, but in fact a rogue planet called Nibiru that would bring about the end times on Earth. After all, the comet's name could be taken as a spooky acronym: "Extinction-Level Event: Nibiru Is Nigh."
Those ideas were pure nonsense, Yeomans said.
"Elenin was a second-rate, wimpy little comet that never should have been noted for anything, really," he told SPACE.com. "It was not even a bright one."
Elenin's remains will not be the only objects about to make their closest pass of Earth. One day after the Elenin flyby, the small asteroid 2009 TM8 will zip close by. Like Elenin, it poses no risk of striking our home planet.
Asteroid 2009 TM8 is about 21 feet (6.4 meters) wide and the size of a schoolbus. It will come within 212,000 miles of Earth – just inside the orbit of the moon – when it zips by on Monday morning (Oct. 17).
Say goodbye to Elenin
Elenin was named after its discoverer, Russian amateur astronomer Leonid Elenin, who spotted it in December 2010. Before the icy wanderer broke up, its nucleus was likely 2 to 3 miles (3 to 5 km) in diameter, scientists say.
Elenin never posed any threat to life on Earth, Yeomans said. It was far too small to exert any appreciable influence on our planet unless it managed to hit us.
"Just driving to work every day in my subcompact car is going to have far more of a gravitational effect on Earth than this comet ever will," Yeomans said.
Elenin's supposed connection to earthquakes was just a correlation, and a weak one at that, he added. Relatively strong earthquakes occur every day somewhere on Earth, so it's easy — but not statistically valid — to blame some of them on the comet's changing position.
Yeomans views the frenzy over Elenin as a product of the Internet age, which allows loud and often uninformed voices to drown out the rather more prosaic results that scientists publish in peer-reviewed journals.
"It's a snowball effect on the Web," Yeomans said. "You get one or two folks who make an outrageous claim, and a bunch of others pile on. Some folks are actually making a living this way."
Elenin's crumbs will soon leave Earth in the rear-view mirror, speeding out on a long journey to the outer solar system. But Yeomans doesn't think the departure will keep the conspiracy theorists down for long.
"It's time to move on to the next armageddon," he said.