NASA is vigilantly scanning the skies for menacing asteroids.
Recently, the space agency captured its first detailed views of asteroid 2008 OS7, a rock some 650 to 1,640 feet (200 to 500 meters) across. It passed 1.8 million miles (2.9 million kilometers) from Earth in early February, which in cosmic terms is quite close. That's just 7.5 times the distance between our planet and the moon, NASA explained.
Fortunately, this asteroid's trajectory posed no danger to us Earthlings. Overall, there's little risk from large asteroids impacting Earth anytime soon.
"There was no risk of the asteroid — called 2008 OS7 — impacting our planet, but scientists at NASA’s Jet Propulsion Laboratory in Southern California used a powerful radio antenna to better determine the size, rotation, shape, and surface details of this near-Earth object (NEO)," the space agency said in a statement.
Below, you can see eight views of this asteroid, taken with a giant radio telescope in the California desert. (Radio telescopes capture images of asteroids by beaming a signal to the object of interest, and then an antenna captures the reflected radio waves.) These radio dishes can be huge. The instrument that captured these views of 2008 OS7, the Goldstone Solar System Radar, is 230 feet (70 meters) across.
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Though there are millions of asteroids in our solar system, today our cosmic neighborhood is much less chaotic than during its creation some 4.5 billion years ago, when objects were incessantly colliding (and some amassed together, forming planets and moons).
"The solar system used to be a lot more violent than it is now," Sally Dodson-Robinson, a planetary scientist at the University of Delaware, told Mashable last year.
"The solar system used to be a lot more violent than it is now."
Astronomers have already found over 90 percent of the half-mile-plus "planet-killer" asteroids that at times pass near Earth's neighborhood, and there's no known threat of collision from these giant rocks for the next century; meanwhile, the likelihood of an impact in the next thousand years is exceedingly low.
What's more, astronomers have found over 10,000 nearby space rocks ("nearby" often means many millions of miles away) that span over 460 feet across, with some 500 more such objects sleuthed from the dark skies each year. (These have the potential to cause vast regional destruction, and an estimated 15,000 remain undiscovered.)
It's normal for asteroids to pass through Earth's neighborhood, but a significant impact is indeed rare:
- Every single day about 100 tons of dust and sand-sized particles fall through Earth's atmosphere and promptly burn up.
- Every year, on average, an "automobile-sized asteroid" plummets through our sky and explodes, explains NASA.
- Impacts by objects around 460 feet in diameter occur every 10,000 to 20,000 years.
- A "dinosaur-killing" impact from a rock perhaps a half-mile across or larger happens on 100-million-year timescales.
Topics NASA
