[meteorite-list] No, Asteroid Aphophis STILL Won't Hit Us in 2036

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 13 Jan 2016 16:27:35 -0800 (PST)
Message-ID: <201601140027.u0E0RZps010796_at_zagami.jpl.nasa.gov>

http://www.slate.com/blogs/bad_astronomy/2016/01/04/asteroid_apophis_will_not_hit_earth_in_2036.html

No, the Asteroid Apophis STILL Won't Hit Us in 2036
By Phil Plait
January 4, 2016

We are safe from an Apophilypse.

Wait, what? People are still fearmongering about Apophis? Seriously?

OK, let's start this off with the conclusion: Like the title says, the
asteroid Apophis is not going to hit us in 2036. In fact, the cumulative
chance it will hit us in the next century is less than 1 in 100,000.

In other words, we're safe.

So, what's going on?

This latest doom crying nonsense to abuse astronomy comes to us from Sputnik
News. It got picked up at various other places, including Christian Today
and that bastion of peer-reviewed science, Facebook.

The article is interesting; it has some things in it that are true, some
that are kinda half-true, and others that are just outright misleading.
For example, it says,

Apophis will approach Earth at a distance of 37,000-38,000 kilometers
on April 13, 2029.

This is true. Apophis was discovered in 2004, and after a few observations
it was determined that it would make a very close approach to Earth in
2029, even closer to us than orbiting geosynchronous satellites! Still,
the chance of an impact was small, and as more observations were made
it became clear it would definitely miss us on that date.

However, shortly thereafter things got sticky. It was discovered that
while it would miss us in 2029, it will pass so close to Earth that our
planet's gravity would strongly affect the asteroid's orbit. The closer
it got to us, the more its path would be warped. And if it passed at just
the right distance, its trajectory would be changed by just the right
amount to bring it back to Earth in 2036 - and possibly impact us.

Yeah, that's a problem. Apophis is about 325 meters across, and so massive
that were it to hit, it would release the energy equivalent to more than
1 billion tons of TNT exploding, at least 20 times more than the largest
nuke ever detonated!

So that is something we'd rather not see happen. But would it?

The exact path of the 2029 pass is critical for the 2036 collision. In
the earlier encounter, the asteroid would have to pass through a very
narrow volume of space near the Earth called a "keyhole"; if it got too
close to Earth, then its orbit would change so much it would miss in 2036,
and if it didn't get close enough then again, the change in its orbit
would guarantee a miss. But if it got it just right, drilled right through
the keyhole, then seven years later: bang.

The question then became, will it miss the keyhole, or are we in serious
trouble?

The more observations of an asteroid we make, the better we can determine
its orbit. As more astronomers watched Apophis, the chance of an impact
dwindled; over time it became clear it was unlikely to pass through the
keyhole in 2029, so a 2036 impact was unlikely as well.

Then, in 2013, we got great news: Radar observations, which are extremely
accurate, ruled out a keyhole shot in 2029. That means that in 2036, Apophis
will miss us by more than 20 million kilometers (50 times the distance
of the Moon). We're completely safe.

So why then is Sputnik News reporting we might get it in 2036?

The article is confused at best, saying the asteroid may hit us, and also
saying it won't. The headline reads, "Russian Astronomers Predict Apophis-Earth
Collision in 2036," but then the very first line is

Russian astronomers have predicted that asteroid Apophis may strike Earth
on April 13, 2036 [emphasis mine].

What is it? "May" or the implied "will" in the headline? Sigh.

The Christian Today article is even worse. The headline there is, "Giant
Asteroid Could Hit and Destroy Earth on April 13, 2036, Russian, U.S.
Scientists Warn". Um, no. Even though an Apophis impact would be really
bad, it would be far smaller than, say, the one that wiped out the dinosaurs,
and note that the Earth is still here.

But then, amazingly, the article gets even worse than that. They quote
American asteroid astronomer Don Yeomans:

"There is a chance in 2036 [that Apophis will hit Earth]," Donald Yeomans,
head of NASA's Near-Earth Object Program Office, recently told LiveScience.com.
That struck me as odd; I know Don and I'm pretty sure he wouldn't say
that. I emailed him, and he replied:

99942 Apophis has no chance of hitting Earth in 2036 and that has been
the case since at least early 2014. I think I've been misquoted - if
indeed I talked to these folks at all. I could not have talked to them
recently since I've been semi retired since January of 2015 and have not
been the Manager of NASA's Near-Earth Object Program Office since then.
Heh. So maybe he said something like this back before 2013, when there
was still a very small chance of a 2036 impact, but a quick Web search
by the article author would reveal it's no longer the case. So that article
stretches the word "recently" past the breaking point. Update, Jan. 5,
2015, at 14:00 UTC: That interview Don gave was to LiveScience and was
from 2011, long before the new radar observations, as I had surmised.
Thanks to Peter Thomas for pointing that out.

Not surprisingly, I got emails and tweets about this from people who were
curious and/or frightened about this news. So let me reiterate what I've
said so many times before: When it comes to asteroid impacts, do not trust
the non-science media.** Not because of any conspiracy or anything like
that; it's simply because the vast majority don't have the scientific
expertise to correctly evaluate this sort of news. There used to be good
science coverage in American news, but most agencies have cut back on
their science reporting in recent years. Couple that with rampant click-baitery,
and the result is nonsense like this story.

And the one before it. And before that. And before that, and before that,
and before that. And and and.

If it's space or astronomy news, go to a good news source. This very blog,
for example, or Universe Today; or you can follow real astronomers on
Twitter. Or, y'know, NASA.

If there really is a chance of an actual asteroid impact, then you can
be sure we'll be talking about it. And best yet, we'll be talking about
it rationally, realistically, and scientifically.

* Correction, Jan. 5, 2015, at 14:00 UTC: I had included a radar observation
of an asteroid that I identified as Apophis, but it was actually an asteroid
called 2007 PA8. To avoid any further confusion I simply removed it.

**Have you ever noticed how "non-science" and "nonsense" sound so similar?
Huh.
Received on Wed 13 Jan 2016 07:27:35 PM PST