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LOS ANGELES — A small asteroid or piece of space junk recently discovered by scientists has a 1-in-500 chance of hitting the planet in 30 years, far greater odds than any similar object yet found, experts announced Friday. 

Though the chance of a collision remains small, it is about a thousand times greater than for any other asteroid-like object yet discovered, said Paul Chodas, principal engineer of the Near-Earth Object Program Office at NASA’s Jet Propulsion Laboratory. 

The object, designated 2000 SG344, is believed to be 98 to 230 feet long. It was discovered Sept. 29 through a telescope in Hawaii. 

Current projections are that it will reach Earth on Sept. 21, 2030, but miss the planet by 15 times the distance between the Earth and moon. 

However, scientists are uncertain about the exact orbit so cannot rule out a collision.  

The possibility of an Earth-impacting orbit was confirmed this week by experts at JPL and in Finland and Italy. 

More observations are needed to pin down the object’s size; right now, it’s just a bright spot in space.  

But if it turns out to be an asteroid – and a collision occurs – more than 23,000 tons of rocks could come hurtling through the atmosphere. 

“It would be equivalent to a fairly sizable nuclear blast” if it actually hit, said Donald Yeomans, manager of the near-Earth office. 

For now, though, that is “fairly low in terms of concern,” he said in a teleconference call. 

Scientists aren’t sure whether the object is a chunk of space rock or perhaps something manmade. 

The orbit – circular, close to the sun and in about the same plane as Earth’s – is unusual for an asteroid, leading to suspicions that it might be a used rocket stage, possibly one jettisoned from an Apollo launch in the 1970s, scientists said. 

In that case, the object would have much less mass and wouldn’t pose any danger in a collision because it would burn up in the atmosphere. 

The object currently is about 8.4 million miles from Earth and moving away.  

Further observations must be made before it drifts out of sight around the sun, which it orbits about every 354 days.  

The orbit is faster than Earth’s, so the object pulls ahead of the Earth, which catches up about every 30 years. 

The object’s discovery is the product of an asteroid-hunting program that found more than 8,600 more benign objects in September alone. 

Yeomans said that the odds of the object hitting the Earth actually are smaller than the likelihood of a collision “by an object of comparable size that we don’t know about” in any given year. 

“The interest in this object is that we know it’s there and we know it’s coming,” he said. 

On The Net: 

JPL: http://neo.jpl.nasa.gov.