Back in the eighties people laughed at scientists who talked about the threat from asteroids. Then we got better tools, and started tracking them. Now we are finding more every night.
Not only are there 27,000 near Earth asteroids that we know of, in the rest of the solar system we have found a few more, like 750,000. All this since the late 1990s.
Some computer somewhere is tracking all those orbits and arcs into the future. How often do these rocks run into each other and generate surprises?
Just how many threatening asteroids are there? It’s complicated.
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“If you talk to the scientists who were studying this in the ’80s, there’s a phrase they often refer to called the giggle factor,” Carrie Nugent, a planetary scientist at Olin College in Massachusetts, told Space.com. “They’re basically saying that they couldn’t talk about this scientific topic without people kind of laughing at them.”
It looks like we’ve probably found all the big one-kilometer-wide asteroids that might pose a problem. And the little rocks will just burn up on entry. So it’s the middle sized ones (140m – 1000m) that we don’t know about which pose the biggest threat.
Despite finding 27,000 near Earth objects, the experts guess that we still don’t know where 60% of the “half kilometer” type ones are.
For a change, it’s nice to talk about a science that’s not political.
If a big rock were on the way it would put Woke science back in its box.
Scientists believe they’ve found nearly all the largest asteroids — those larger than 3,300 feet (1 km) across — and know that these are the easiest to find anyway. And while tiny near-Earth asteroids are plentiful and difficult to find, they are also the most likely to fall apart harmlessly in Earth’s atmosphere.
So it’s the middle size category of asteroids — those more than 460 feet (140 meters) but less than 3,300 feet wide — that most worries planetary defense experts. “That’s where it’s more likely that an impact could happen,” Fast said. “Even with those, we’re talking maybe timescales of centuries or millennia.”
As of the end of 2020, estimates suggested scientists have found just 40% of near-Earth objects of this size; this year has added 500 to the tally. While that number is impressive, NASA’s planetary defense office estimates that at the current pace, it will take scientists 30 more years to have identified 90% of objects this size, a goal that Congress asked NASA to reach by 2020.
The dangers that lurk in the void,
Crossing paths with a vast asteroid,
An extinction event,
On destruction hell-bent,
Best nudged off its path to avoid.
–Ruairi