Re: Norway hit with Hiroshima scale metorite

On Mon, 12 Jun 2006 20:59:22 GMT, "Jerry Okamura"
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"Rumpelstiltskin" <PleaseDoNotReplyByEmail@xxxxxxxxxxx> wrote in message
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On Mon, 12 Jun 2006 18:06:08 GMT, "Jerry Okamura"
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"Rumpelstiltskin" <PleaseDoNotReplyByEmail@xxxxxxxxxxx> wrote in message
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On Sun, 11 Jun 2006 11:28:22 -1000, Alvin Toda <aet@xxxxxxxx> wrote:

On Sun, 11 Jun 2006 02:50:13 GMT, Rumpelstiltskin
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On 10 Jun 2006 06:56:59 GMT, Earl <neptune@xxxxxx> wrote:


Yes the sky is falling

http://www.aftenposten.no/english/local/article1346411.ece


I ran into the article below about Earth's temporary moons
while trying to find more about this asteroid. One of the
temporary moons, 200 meters in diameter, is thought to have
been in orbit around the earth for the last 500 years so far.

http://www.hypography.com/sciencearticle.cfm?id=7036

and here's something on the crater under Antarctic ice that
might have triggered the greatest of all the great extinctions,
the Permian extinction, 250 million years ago. The article
may be gone soon, judging from the brevity of the URL.
It's dated
Earth Science News: Monday, June 05, 2006

http://geology.com/news/

This asteroid seems to be about the size that a telescope nearby on
Maui is attempting to detect. But perhaps the scope's main job really
is to look for something coming from North Korea?


We know about all the really big ones that are in stable
earth-crossing orbits, but even little ones can do a lot of
damage. And what about something that just got knocked
out of the Asteroid or Kuiper Belts or Oort cloud and is
heading toward us for the first time? Earth is a tiny target
compared to Jupiter, but nevertheless, that plume and
earth-sized cloud of disturbance on Jupiter after it was
hit by a big comet a few years back does give one
something to think about.

I found a list of the big Kuiper Belt objects found so
far. One of them seems to be bigger than pluto.
http://www.ifa.hawaii.edu/faculty/jewitt/kb.html
Larger still than Pluto and the newly discovered Kuiper
Belt object is Neptune's moon Triton, whose orbit
around Neptune is anomalously retrograde, inclined far
from the usual plane of the planets and large moons
in the solar system, and in an unstable orbit which is
spiraling toward Neptune such that it will collide with
the planet on a time scale very short compared to the
time scale of the solar system. Many people suspect
that Triton is a captured Kuiper Belt object.

I was watching one of my favorite channels last night...I think it was the
Science Channel. In that segment, they were showing what scientist would
believe would happen if a large asteroid hit the ocean off Southern
California. But in response to your posting, the people who do try to
find
and track large asteroids, pointed out that they have catabloged only
about
10% of the asteroids in near earth orbit.




Those 10% include all the big ones (I hope), though as noted
even the little ones can do a lot of damage, especially if they hit
a city. There's a lot of space out there to investigate. Just a
few years ago, if I recall aright, the earth was passed within
about three times the distance to the moon, which is close by
solar-system standards, by an earth-crossing asteroid that nobody
knew about until they spotted it as it was leaving.

Nope. Apparently the only way they can detect any of them is by their
movement. So, they take images of the area they have their telescopes
pointed at twice (I think it was in a twenty four hour period). They then
visually inspect the images. They know that the object is moving, because
it is in a different location from the first image they took. Now these are
not big spots on their telescopes, but really really small spots. Kind of
like a brute force way to finding these things. And that only applies to
asteroids. As I understand the issue of space objects, it does not include
comets, which are generally not detected (at least the new ones), when they
pass close to the sun, at which time you see that tell tale tail of the
comet, as it starts to shed its moisture. Shoemaker Levy is a good example.



The technique for finding small moving objects is called
"blink photometry" I think, though I did only get one google
hit on that term when I checked. That technique is to
take photographs of the same patch of sky at different
times, then project two such photographs alternately on a
screen in rapid succession. Anything that moved will seem
to jump back and forth, which of course really stands out
for humans because that's one of the ways we've evolved
to quickly separate tigers running toward us from the trees
that stay pretty much in the same place all the time. That's
why I say we've probably found all the big earth-crossing
objects. (An "earth-crossing" object conventionally means
something that's in an orbit that repeatedly crosses very
close to earth's orbit, not something that's just passing by
one time.)

Even though Pluto is sometimes closer to the sun than
Neptune, they're not "crossing" because Pluto's orbit
is very eccentric, and tilted compared to the orbit of
Neptune, so they're in no danger of colliding. Imagine
cutting through a hula hoop and slipping one side of another
hula hoop past the cut, then sealing the cut again.
If you don't hold the hula hoops so that they're at the same
slant, there are lots of ways to hold the two hoops such
that no part of either comes very near a part of the other.
The two hula hoops would by like the orbits of Neptune
and Pluto. You in the middle would be the Earth or
the Sun.

 
"Necessity is the plea for every infringement of human freedom: it is the
argument of tyrants; it is the creed of slaves" -- Wm. Pitt the Younger
.

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