The sky is falling, and scientists are amped

Story highlights

• A space object is expected to fall to Earth Friday, probably in the Indian Ocean
• Observations suggest it's a spent stage from a man-made rocket

(CNN)Heads up!

A mysterious object is headed for a fiery collision with Earth on Friday, but scientists say there's nothing to fear.

Astronomers who've spotted the object streaking through space say it's too light to be a space rock. They think it's probably the abandoned upper stage from a man-made rocket finally coming home.

At a couple of meters (about 6.5 feet) in diameter, it will pose little danger to anyone on Earth, the European Space Agency says.

The bits of the object that don't burn up on entering the atmosphere should come down harmlessly about 100 km (62 miles) off the southern coast of Sri Lanka, the agency predicts.

"But the show will still be spectacular, since for a few seconds the object will become quite bright in the noon sky," the European Space Agency's Near Earth Object Coordination Centre wrote on its website.

A NASA illustration of space junk orbiting Earth.

Observers spotted the object, tagged WT1190F, on October 3, ESA said. According to the agency, they then realized it had been spotted before, in 2013, by the Catalina Sky Survey at the University of Arizona.

Now, astronomers are champing at the bit to observe the object as it approaches and enters the atmosphere.

ESA Astronomer Marco Micheli said it will provide "an ideal opportunity to test our readiness for any possible future atmospheric entry events involving an asteroid, since the components of this scenario, from discovery to impact, are all very similar."

The agency says it thinks the object is probably a spent rocket booster because analysis of its movements suggest it has a density of about 10% that of water.

"This is too low to be a natural space rock, but it is compatible with being a hollow shell, such as the spent upper stage of a rocket," the ESA said.

If it turns out to be man-made space debris, it would be "a lost piece of space history that's come back to haunt us," said Harvard-Smithsonian Center for Astrophysics astrophysicist Jonathan McDowell said in the science journal Nature.

That harkens back to the reentry of the Skylab space station, an event that became a media sensation back in 1979. Parts of the station survived the trip and showered Australia with debris.

Now that scientists know WT1190F is coming, they're organizing a worldwide campaign to observe its approach and impact.

Scientists have long been alarmed by the prospect that a previously unknown asteroid could suddenly pop into view on a collision course with earth.

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In fact, the encounter comes just a few weeks after a newly spotted asteroid, traveling 78,000 miles an hour, is expected to zip past Earth this Friday and Saturday at a distance of about 300,000 miles.

Dubbed the Halloween asteroid, that rock is some 15-30 times the size of an asteroid that exploded in the sky over Chelyabinsk, Russia in 2013, causing widespread damage and injuries.

Astronomers found the Halloween asteroid only in early October, and they were caught entirely by surprise by the Chelyabinsk rock.

As for this new object, the inevitable conspiracy theories have already popped up surrounding its name, whose "WTF" letters recall a common if profane acronym, and its projected date of impact: Friday, November 13. Some of the more suspicious among us believe space agencies are in the business of concealing alien life and claim the object is really an alien craft, or something else sinister.

"First things first before anybody shouts, this could very well be space junk, BUT the big question is, well we ever know??," the website UFO International Project wrote. "Unless we have millions of pounds worth of deep-sea investigating equipment it is extremely unlikely we will ever discover what this UFO called 'WTF' actually is!