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On Mon, 10 Apr 2000, jennifer wrote:
> 1. Why do you think this subject has got so much attention lately? I mean=
> there has been made two great movies about it (Deep Impact and Armageddon=
).=20
> Could it have to do with what happened on Jupiter 1994?
Until recently, nobody thought that the Earth was in danger of being hit
by a comet or an asteroid. But the impact of comet Shoemaker-Levy 9
into Jupiter showed that impacts still happen in the solar system. Also,
in the past few years a giant (nearly 150 km) crater was found on the
Mexican coast, and the evidence seems to indicate that this crater was
caused by an asteroid impact that killed off the dinosaurs 65 million
years ago. So, suddenly the Earth doesn't seem as safe anymore.
> 2. Which do you think is the biggest threat, an asteroid or a comet? Why?
Personally, I think a comet is a bigger threat. Both would do about the
same amount of damage. But asteroids orbit the sun close to the Earth, so
we can use telescopes to search for them, and then we can use computers to
calculate their orbits thousands of years into the future. If the Earth
seems to be in danger from an asteroid, most likely we will have hundreds,
if not thousands, of years of warning, which gives us lots of time to come
up with a good solution.
Comets, on the other hand, spend most of their orbits far away from the
sun (up to a couple of light years away), and this is too far to be seen
by telescopes. So we don't find comets until they travel into the inner
solar system - usually less than a year before they pass by the Earth.
So, with a comet, we would only have, at most, a few years' warning of an
impact.
> 3. How soon (or late) can we discover a =93Doomsday=94 comet or asteroid?
There are efforts underway to look for near-Earth asteroids (the only
asteroids that are dangerous). The search only takes a few people using
fairly small telescopes, and so is relatively cheap. And, in a couple of
decades, we should know all the orbits of the most dangerous asteroids.
Then, we should have hundreds of years' of notice of an impact.
As I said above, for comets we would only have a couple years' worth of
warning.
> 4. What can we do to provide it from hitting earth?
This is still uncertain. Ideas range from putting a rocket engine on an
asteroid (if we know the asteroid's orbit far enough ahead, a tiny rocket
motor can avert disaster) to trying to use a nuclear bomb to force the
comet/asteroid into a different orbit. We know so little about comets and
asteroids, however, that we still don't know how to change their orbits.
One thing is certain, though - blowing an asteroid or comet to bits will
NOT protect the Earth. Whether an asteroid is one large rock or hundreds
of small rocks, it still carries the same amount of energy, and all that
energy would still hit the Earth. A sudden rain of billions of meteors
would heat up the atmosphere enough that we would all be cooked!
> 5. When do you think the next smaller asteroid, comet or meteor will come=
> and hit the earth and cause a local disaster, and when do you think the=
> =93Doomsday=94 comet or asteroid will come?
Meteors large enough to do damage on a local scale probably hit the Earth
a couple times a century or so. We don't notice most of these events,
because the meteors hit the ocean 3/4 of the time. In the 1910s,
something exploded in the air above Tunguska, Siberia, destroying trees
for many miles around, and killing a couple of people. If that object had
hit New York City, the entire place would have been destroyed completely.
Luckily, though, the amount of the Earth that is covered by people is very
small, so most localized impacts won't do much damage.
The rate of impacts large enough to cause large-scale catastrophes is
unknown. Estimates range from once every million years to once every few
hundred million years. The only thing we can say for certain is that
asteroids and comets DO hit the Earth, and those that do must cause
serious damage. But we know that these events must be rare, because mass
extinctions on Earth are fairly rare (and only a couple of these show
signs of being caused by impacts.)
> 6. If you have seen anyone of these two movies that I mentioned earlier,=
> what do you think about them? How much truth is it in them? For example, =
do=20
> you think that the authorities would try to hush it up, would that be=20
> possible?
The movie "Deep Impact" is much more scientifically accurate than
"Armageddon." We know comets exist and are a threat, but no asteroid the
size of the object in "Armageddon" exists in our solar system. =20
I think that, as humans, we would do all in our power to prevent an impact
and to protect ourselves if we could not prevent it. I doubt that such a
secret could be kept by the government - there are too many people
watching the skies and discovering asteroids and comets, and the
large-scale preparations needed to protect the Earth would involve too
many people to keep it a secret. Let's face it - if Monica Lewinsky made
the news (despite only a very few people knowing about her relationship
with the president), a looming major disaster would not remain a secret
more than a few days.
The chances of an asteroid impact occuring within our lives are EXTREMELY
low. The costs of looking for dangerous asteroids and comets are also low
- a few million dollars a year, or a penny from every man, woman and child
on the planet. So, as long as we keep a watchful eye on the sky, there is
no need to worry ourselves about an asteroid impact. It's like living in
California - we KNOW that a big earthquake will occur somewhere sometime,
but we don't let that fear control our lives. We take the necessary
precautions, and when it comes, most people will be ready. The same
should be true for a looming asteroid impact, except that the impacts
occur much, much less frequently then earthquakes. If we prepare and have
contingency plans, there is no need to live in fear. We have the ability
to spot danger and protect ourselves from it - it just takes a very small
amount of time and money and brain-power.
I hope this answers your questions!
Thanks for writing!
Sincerely,
Kurtis Williams
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