Expert: Tom Whiting - 9/29/2006

Question
Thank you for the information you have sent me, but i was watching a show last night on the History channel about asteroids and comets and how everything happened., and in it they said the reason that the dinosaurs were exterminated because of the gases and smoke and ash covered the globe trapping in the heat and setting fire almost everywhere. And that this is one reason that the ice age occurred. Isn't this a possible outcome of our future if this asteroid hit the earth. couldn't we also be exterminated like the dinosaurs were? Thank you, i'm excitedly waiting to hear your response.

Tanner
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Followup To

Question -
I dont know the difference between astronomical and astrological so im sorry if i get this wrong. Do you know an approximate year that the world will end? And can you give me any information on the closest object to us in space that is a threat? Thank you very much.

Tanner

Answer -
Hi Tanner,
Well, astronomical, or astronomy, is the scientific study
of the Universe and the bodies contained therein....
Whereas astrological, or astrology, is the false belief
(some claim a false *religious* belief) that by some mysterious mechanism (as yet to be determined  ;-) a person's life is ruled or dominated (or pre-determined ??)by the positions of the moon, sun, and planets at the time of your birth.  Which, of course, is ridiculous to the discerning logical thinking student.  {It might interest you to know that not
one true astronomer subscribes to astrology....as we know
better}. This is also true of fortune telling, ghosts, UFO's
Alien lifeform visitations, goblins, Ouiga boards, the occult...we subscribe to none of that stuff.

End of the world, for sure?
Yes, the Earth, Venus, and Mercury will come to their end
(for sure!!) about 4,000,000,000 AD common date, plus or minus a few hundred million years, when our sun begins to run out of hydrogen fuel and begins to swell into the Red Giant stage of its life cycle.  
But not to worry, as 4 billion years gives us plenty of time to find a .....new planetary home around another star.  Hopefully, next time, we will find a suitable planet around a little red dwarf star, because those types of  stars have lifespans that are about 6-10  *trillion* years before using up all their hydrogen fuel.  (That's right, the bigger and hotter the star, the faster it uses up its fuel supply!!)   The big, bright
blue-white supergiant stars like Deneb and Rigel have lifespans of  "only" 20-25 million years, before they go supernovae!!  Whereas our own sun, a solar-type star,
has a total lifespan of about 10 billion years, and we've
already used up about 1/2 of that time.  But we still have
plenty of time left.....4 billion is a BIG number.

Closet object to us that is a rare, but possible threat? Only one known at this time.
In fact the November 2006  issue of Sky & Telescope
magazine (our 'bible' as it does not sensationalize astronomy)
has an excellent article about a 1000 foot diameter
(320 meters) asteroid called Apophis (also called asteroid
2004MN4) which will miss the Earth by only 2.5 Earth diameters (about 20,000 miles) on April 13, 2029.  That is
no problem, but there is a one in 48,000 chance this
asteroid will hit "The Keyhole"....a region of space close
to the Earth that insures an impact trajectory exactly 7 years
later.....April 13, 2036.  While this is still a very low
probability, it presently does have NASA's attention.  They are already in the planning stages to send a mission with a
transponder on board to soft land on the asteriod, which
would provide us accurate location information such that
we could pre-determine a very accurate orbit of this asteroid,
better than either visual or radar sightings can provide us.  This is a possible planned launch in 2013.  Fortunately, we still have lots of time on our side.

In any case, a 1000 foot diameter impact would not mean
total devastation worldwide....an asteroid that size hitting,
say, in the Atlantic Ocean would produce the tsunami-sized
waves that struck Indonesia and Thailand back in 2004.
A ground hit would be devastating to a particular area of
about 300 miles across, so it would knock out one state, or
one European country.   
Even at the Creataceous-Tertiary event 62 million years ago,
that took out 70% of the lifeforms (including the dinosaurs)
that body was estimated to be 6 miles in diameter.
It's estimated that an asteroid would have to be over 10
miles in diameter to eliminate all life on the surface of the
Earth.....and nothing like that is anywhere near us, at present.
But for updates on asteroid Apophis, just google it and I'm
sure all sorts of website information will .....pop up.  ;-)

Hope all this helps,
Clear Skies,
Tom Whiting, Pres. ECMOG
Erie, PA

PS....actually your initial statement should have read,
" I don't know if this is astronomical, or science fiction.....

But no, this is not sci-fi....this is the straight skinny that I've
given you above.



FOLLOW UP:
You have to be careful what website you use for Apophis....
due to a small probability of collision,
it has brought out a lot of sooth-sayers, crazies, nuts,  and sensationalists.... so the best one I just found, and most accurate is
http://en.wikipedia.org/wiki/99942_Apophis

Clear skies,
tom

Answer
Hi Tanner,
Well, this rock, 99942 Apophis, isn't big enough to pull that
trick off --a major extinction.  Of course, we could be hit again with a 6-10 mile size rock eventually.  That's why about 10-15 years ago, we started the NEA (Near-Earth Asteroid) program, trying to classify and find every body that is in our region that is over 50 feet in diameter, and we expect to have found nearly 90% of them by the year 2020.  In fact, it was that very program that discovered Apophis.

Well, as far as taking a big hit....I mean we get hit everyday
by micrometeoroids, and perhaps once a month with a football sized rock.  It's all in the odds which is based on size.

Typically every 100 years or so, we take a hit by something
100 feet in diameter or thereabouts.  And of course, 7 out of
10 will be oceanic hits (oceans cover about 70% of our surface)....
But the timeframe really increases as you go up in size
from there.
I think we can expect a 3-6 mile diameter hit every 100 million years or so, so it could happen tonight, or it could happen 100 million years from now.  There is just no way of knowing, but I wouldn't lose any sleep over it, because (1) the odds are
very low (when is the last time you saw that happen? - about
62 million years ago, and even then, 30% of the lifeforms on
the Earth survived it-fortunately for us the mammals survived it too), and (2) there is probably nothing we can do about it
anyway, if the rogue asteroid comes from the sunward side
of the Earth...we wouldn't see it coming in.  (the sun blocks
about 15% of our sky at any one time).
But in any case, that's the whole purpose of our current
NEA program....we realize that we live in a dangerous
Universe, and it would be nice to find out well ahead of time
that anything is coming our way, and maybe we can do
something about it.

Realize too (and this will help you sleep better tonight) that
the Earth is a very small, very fast moving target, and very
difficult to hit.  I've read that it is equivalent to you flying
in a light plane, diving at 150 miles per hour on a rabbit running at full speed on an open field, and you have a .22 rifle and you get one shot per year at that rabbit, diving down on it at 150 miles per hour, without using any sighting or
aiming device while hanging out the door of the light plane.  It will be many years of trying before you
score even a partial hit...and even when you do, the odds
are you'll just wound the rabbit, not kill it.
Oh, and did I mention that you are blindfolded too; as the
asteriod doesn't know that the Earth is up ahead.

The Earth is quite small as planets go, only about 8,000 miles
in diameter, and we're moving at 18.5 miles per second
around the sun, which means we move our own diameter
every 432 seconds, or 7.2 minutes.  Also, space is 3-dimensional....so a particular rogue "rock" not only has
to be crossing the ecliptic (Earth's orbit) at the moment
it encounters the earth, (otherwise it will pass above or
below the Earth) but it has to also be ON TIME, within that
7.2 minute timeframe (otherwise it will pass either ahead of,
or behind the Earth).....so a rogue asteroid has to not only
be on the right orbit, it has to be on the right time!
Bottom line is....we are one tough target to take a random hit
from outer space!

So that's why I don't lose any sleep over it.
And you shouldn't either, plus we have thousands of us
astronomers watching the sky every night, in addition to
those Goverment funded programs mentioned above.
So I guess we're doing the best we can at keeping us all safe.

Hope all this helps,
Clear Skies,
Tom Whiting
Erie PA