Another Big Asteroid will Fly Past Earth: Why does this keep Happening?

It seems that in recent years, asteroids have been flying past Earth with increasing frequency.  Does it mean that more asteroids are coming around? Is it the beginning of the end? Will one of them hit us soon and doom us all?

Probably not, but there’s always a chance.

It’s almost certain that the reason we’ve been able to find so many new asteroids, and especially near-Earth asteroids, is because of the technology increase in Astronomy the past few years.  New telescopes and tracking methods exist with the sole purpose of finding near-Earth asteroids, somewhat of an early warning system for humanity.  The two that come to mind are LINEAR and NEOWISE, both NASA projects.

The scary part is that close calls have been a regular occurrence since the beginning  of the Solar System, except we had no idea about most of them.  We have had no clue how close we have come to total extinction.

On January 26th, another big Asteroid will come give us a shave.  Asteroid 2004 BL86 (discovered in 2004 apparently), which is about 550 Meters across, will come within 1.2 Million Km of Earth, about three times the distance between the Earth and the Moon.

Credit: NASA/JPL-Caltech

Now I know what you’re thinking.  1.2 Million Km is a long way away. But let’s think about Mars, at 401 Million Km.  And Mars is the second closest planet to us on average.  Suddenly the asteroid seems kind of close.

This also brings up another point – Earth is pretty small, so it seems really unlikely that anything will hit us any time soon.  How do we determine what’s dangerous in terms of Asteroids?  We use something called the Torino Scale.

The scale shows the danger of an impact in terms of impactor size and probability of hitting us.  The green part of the scale is interesting because it covers objects that range in size from 20m to 5Km in size.  They have the same danger level because they don’t have much of a chance of hitting us.  A 5Km impactor is crazy if it hits us, but with a 0.000001 % chance of hitting us, we aren’t too worried.  The real danger comes when you look at high probability hits.

Remember the Chelyabinsk Meteorite from 2013 in Russia? That was 20m across, and it caused a lot of damage.  A 5Km impactor would be like a thousand nuclear bombs going off.

The scariest part of all is that as time scales increase, the probability of an impact increases.  A 20m Asteroid is expected to hit us once every 100 Years.  A 5Km impact happens once every 20 Million years, okay not so often, except the Earth has been around for 4.5 Billion, so it has been blasted by large impacts time and time again.

The good side of this is that we are getting very good at detecting the biggest ones, that can cause the most damage.  Hopefully we can see them coming with enough warning to know what to do.

But what can we do?

(If you’re thinking about the movie Armageddon, don’t….it is ripe with scientific inaccuracy)


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