A story about debris from outer space was unclear about the size of asteroid 2012 DA14 relative to the size of the meteor that struck Russia. Its diameter was three times larger. Its volume, assuming it was a perfect sphere, was 27 times larger.
While Earthlings were looking one direction, we got nailed from another.
Confident that we would dodge a celestial bullet on Friday morning -- the largest recorded space object ever to pass so close to Earth -- we gazed skyward at asteroid 2012 DA14, relieved that it was a comfy 17,000 miles away and is departing for a very long time.
But outer space had the last laugh.
In a cosmic coincidence, an unpredicted space rock hit us from a different corner of the sky -- injuring and terrifying residents of Russia's Ural Mountain city of Chelyabinsk with its 300 kilotons blast.
It's a troubling reminder of that inevitable day when we cross paths with far more catastrophic space debris.
What happened? Why were we warned only about the rock that didn't matter?
Here's Friday's teachable moment: NASA is quite good at finding the big stuff. It says it's found about 95 percent of all the large asteroids with the potential of entering the inner solar system.
But there are many more small, unruly and elusive meteors -- which are still plenty dangerous.
"Small objects are very difficult to detect, and therefore defend against," said Paul Chodas, research scientist in the Near Earth Object Program Office at NASA's Jet Propulsion Laboratory in Pasadena.
Large asteroids reflect the light of the sun, so they're more easily seen, according to Foothill College astronomer Andrew Fraknoi. Small meteoroids are almost invisible. If Earth were a basketball, they'd be just a grain of flying sand.
About 80 tons of meteorite material rains down upon the Earth every day, said Bill Cooke of the Meteoroid Environments Office at NASA's Marshall Space Flight Center in Huntsville, Ala., in a Friday afternoon teleconference.
Car-sized objects land every month or two, he said. Something the size of what hit Russia might land every decade or two. Friday's two incidents are unrelated; they came from different directions, with different velocities, Cooke said.
The one that shook Siberia was tiny, an astronomical perspective that Russians might dispute. It only measured about 50 feet in diameter, and it exploded before it hit the Earth.
If instead Earth had been hit by an asteroid like DA14 -- which is three times larger, at
Such close encounters could add fuel to the effort to better track flying space rocks. Apollo 9 astronaut Rusty Schweickart's B612 Foundation has been warning about the dangers for years. Schweickart believes the government should boost its $20 million a year budget for asteroid detection; he says it deserves $250 million a year.
Congress also weighed in on Friday, according to The Associated Press.
"Today's events are a stark reminder of the need to invest in space science," said Rep. Lamar Smith, R-Texas, chairman of the House science, space and technology committee. He called for a hearing in the coming weeks.
Once they're found hurtling toward our planet, of course, there's a new challenge: what to do with them.
While scientists have some good ideas, they're still unproven.
Some rely on direct destructive methods, such as a nuclear bomb. Others involve indirect tricks to change a space rock's course, such as "gravity tractors," laser cannons or rockets. Because many asteroids are just flying rubble piles, it may be enough to just loosen up the cluster, rather than destroying or deflecting it.
"Clearly,'' said NASA's Chodas, "more work has to be done."
Contact Lisa M. Krieger at 650-492-4098.
Meteors and meteoroids: A meteoroid is a small rocky or metallic object -- usually between the size of a grain of sand and a boulder -- that orbits the sun. When one bursts into Earth's atmosphere and vaporizes, it's called a meteor, or a "shooting star." Millions of meteors enter Earth's atmosphere every year; most of them are tiny and burn up in a streaking flash across the night sky.
But some crash to the ground. When that happens, they are called meteorites.
Asteroids: They are larger. Rocky or metallic, they also orbit the sun. Historically, objects larger than about 33 feet across have been called asteroids; smaller ones have been called meteoroids.
Comets: These are large bodies of ice, rock and dust -- "dirty snowballs" that can be several miles wide -- orbiting the sun. Debris from comets are the source of many meteoroids.