Do small meteors have steeper (inital) angles?

A problem I have been contemplated lately is the following:

- It seems to me that there should be a difference in the angles
(to Earth's horisontal surface/top of atmosphere) which the
path of a meteor (or meteoroid) makes.
I have done no calculations on this, I just get a feeling for
this solution when loosely considering it.

Because, since a small meteoroid particle, say cm-size or smaller,
would have a far greater tendency to fall into the gravity well
of the Earth, while traveling a randomly path through the solar
system. Since it early on homes in on Earth, it would have
a greater tendency to come more or less straight down to the
atmosphere, having an angle close to 90 deg.
Consider then a large boulder of maybe several meters, or tens of
meters. Since according to Newton's laws it takes a much larger force
to deviate from its straight (more or less) path around the Sun.
So those of the larger ones that are atracted towards the environs of
the Earth, doesn't home in on the Earth, but rather develops a more or
less tangential path to the Earth.
Therefore if a large meteor is observed (not so often), a _typical_
characteristic should be a low angle path, probably less than 10
degrees from the horisontal/tangential.

An example of such was the August 1972 large fireball observed
and photographed in northern US/southern Canada - Utah/Wyoming/Alberta
area. It was big, sizes from 3-80 m have been infered!
It didn't come closer than about 53-58 km, but if it had hit
it would probably have impacted with the energy of a Hiroshima bomb.
So was it a coincidence that this almost approching Tunguska class
meteoroid had a tangential path? Tunguska itself is also said to have
a quite shallow angle path.
Of course a large meteoroid/small asteroid *can* come more or less
straight down - if it was heading our way in the first place - but
this would not be the typical path.

(As bigger meteoroids would maintain their speed and bearing right
down to the impact with the surface, while the smaller ones would be
braked down and always end up with just free fall speeed and coming
more or less straight down, I'm of course here always refering to the
initial angle at the top of the atmosphere.)

So am I wrong in my assumptions?
Can someone tell me if I'm wrong or not...

Is there given a certain distribution function of initial atmosphere
impact angles, given the size of the meteoroids/asteroids?
Any references to be recommended?

Regards,
Bjørn Sørheim

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In article ,
Bjørn Sørheim wrote:
Because, since a small meteoroid particle, say cm-size or smaller,
would have a far greater tendency to fall into the gravity well
of the Earth, while traveling a randomly path...
Consider then a large boulder of maybe several meters, or tens of
meters. Since according to Newton's laws it takes a much larger force
to deviate from its straight (more or less) path around the Sun...

However, the force exerted on it by a gravitational field is proportional
to its mass!

As Galileo showed in his (possibly apocryphal) demonstration from the
Leaning Tower, heavy and light objects respond equally to a gravitational
field. A dust grain and a boulder will follow exactly the same path when
approaching Earth, unless one or the other is also affected by
non-gravitational forces.

An example of such was the August 1972 large fireball observed
and photographed in northern US/southern Canada - Utah/Wyoming/Alberta
area. It was big, sizes from 3-80 m have been infered!
It didn't come closer than about 53-58 km, but if it had hit
it would probably have impacted with the energy of a Hiroshima bomb.

No, it is now thought to have been only about 100t, 2-3 meters across.
Early estimates of its size apparently contained a serious calculation
error.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

( Bjørn Sørheim ) wrote in news:J8LDb.6640$Y06.105436
@news4.e.nsc.no:


A problem I have been contemplated lately is the following:

- It seems to me that there should be a difference in the angles
(to Earth's horisontal surface/top of atmosphere) which the
path of a meteor (or meteoroid) makes.
I have done no calculations on this, I just get a feeling for
this solution when loosely considering it.

Because, since a small meteoroid particle, say cm-size or smaller,
would have a far greater tendency to fall into the gravity well
of the Earth, while traveling a randomly path through the solar
system. Since it early on homes in on Earth, it would have
a greater tendency to come more or less straight down to the
atmosphere, having an angle close to 90 deg.

Dead on arrival. A dust mote and a rock fall at exactly the same rate.
(given lack of air and ignoring radiation pressure, solar wind etc). This
was known to Galileo 400 years ago. It is even taught at school. You must
have been asleep that day.

Llanzlan

SNIP

Bjørn Sørheim wondered:

- It seems to me that there should be a difference in the angles
(to Earth's horisontal surface/top of atmosphere) which the
path of a meteor (or meteoroid) makes.

Because, since a small meteoroid particle, say cm-size or smaller,
would have a far greater tendency to fall into the gravity well
of the Earth, while traveling a randomly path through the solar
system. Since it early on homes in on Earth, it would have
a greater tendency to come more or less straight down to the
atmosphere, having an angle close to 90 deg.
Consider then a large boulder of maybe several meters, or tens of
meters. Since according to Newton's laws it takes a much larger force
to deviate from its straight (more or less) path around the Sun.

And that much larger force is there, according to Newton's law
of gravity. Galileo showed that all bodies accelerate at the
same rate in Earth's gravity. I betcha knew that.

-- Jeff, in Minneapolis

..

"Llanzlan Klazmon The 15th" wrote in message
7.6...
( Bjørn Sørheim ) wrote in news:J8LDb.6640$Y06.105436
@news4.e.nsc.no:


A problem I have been contemplated lately is the following:

- It seems to me that there should be a difference in the angles
(to Earth's horisontal surface/top of atmosphere) which the
path of a meteor (or meteoroid) makes.
I have done no calculations on this, I just get a feeling for
this solution when loosely considering it.

Because, since a small meteoroid particle, say cm-size or smaller,
would have a far greater tendency to fall into the gravity well
of the Earth, while traveling a randomly path through the solar
system. Since it early on homes in on Earth, it would have
a greater tendency to come more or less straight down to the
atmosphere, having an angle close to 90 deg.

Dead on arrival. A dust mote and a rock fall at exactly the same rate.
(given lack of air and ignoring radiation pressure, solar wind etc). This
was known to Galileo 400 years ago. It is even taught at school. You must
have been asleep that day.

Llanzlan


You seem to forget that the inertia of an object is greater the heavier it
is.
It makes perfect sense that it takes the earth longer to influence the path
of a massive object than that of a not so massive one.
They DID teach you about inertia at school, right?

"Laura" wrote in message
...
Dead on arrival. A dust mote and a rock fall at exactly the same rate.
(given lack of air and ignoring radiation pressure, solar wind etc).
This
was known to Galileo 400 years ago. It is even taught at school. You
must
have been asleep that day.

Llanzlan


You seem to forget that the inertia of an object is greater the heavier it
is.
It makes perfect sense that it takes the earth longer to influence the
path
of a massive object than that of a not so massive one.
They DID teach you about inertia at school, right?

Hi Laura,

If you go up to the top of the leaning tower with Galileo and measure, you
will find the lightweight ball does not have nearly as much inertia as the
lead ball of the same size. But when you drop them, even though they have
different inertia, they still are "influenced" at the same rate and hit at
the same time.

Clear Skies

Chuck Taylor
Do you observe the moon?
Try the Lunar Observing Group
http://groups.yahoo.com/group/lunar-observing/

"Laura" wrote in :


"Llanzlan Klazmon The 15th" wrote in
message 7.6...
( Bjørn Sørheim ) wrote in news:J8LDb.6640$Y06.105436
@news4.e.nsc.no:


A problem I have been contemplated lately is the following:

- It seems to me that there should be a difference in the angles
(to Earth's horisontal surface/top of atmosphere) which the
path of a meteor (or meteoroid) makes.
I have done no calculations on this, I just get a feeling for
this solution when loosely considering it.

Because, since a small meteoroid particle, say cm-size or smaller,
would have a far greater tendency to fall into the gravity well
of the Earth, while traveling a randomly path through the solar
system. Since it early on homes in on Earth, it would have
a greater tendency to come more or less straight down to the
atmosphere, having an angle close to 90 deg.

Dead on arrival. A dust mote and a rock fall at exactly the same
rate. (given lack of air and ignoring radiation pressure, solar wind
etc). This was known to Galileo 400 years ago. It is even taught at
school. You must have been asleep that day.

Llanzlan


You seem to forget that the inertia of an object is greater the
heavier it is.

Irrelevant.

It makes perfect sense that it takes the earth longer to influence the
path of a massive object than that of a not so massive one.
They DID teach you about inertia at school, right?



I hope that the tax payer didn't pay for you education. If so, they were
robbed.

Llanzlan.

"Chuck Taylor" wrote in message
...
"Laura" wrote in message
...
Dead on arrival. A dust mote and a rock fall at exactly the same rate.
(given lack of air and ignoring radiation pressure, solar wind etc).
This
was known to Galileo 400 years ago. It is even taught at school. You
must
have been asleep that day.

Llanzlan


You seem to forget that the inertia of an object is greater the heavier
it
is.
It makes perfect sense that it takes the earth longer to influence the
path
of a massive object than that of a not so massive one.
They DID teach you about inertia at school, right?

Hi Laura,

If you go up to the top of the leaning tower with Galileo and measure, you
will find the lightweight ball does not have nearly as much inertia as the
lead ball of the same size. But when you drop them, even though they have
different inertia, they still are "influenced" at the same rate and hit at
the same time.


So, you are saying that a light object moving at high speed, aimed to miss
earth by a small amount (though not close enough to enter the atmosphere),
would be deflected exactly as much by earth's gravity as would a very heavy
object moving at the same speed?
In the leaning tower example, that would be the equivalent of shooting the
two balls out of a cannon, across an airless version of Pisa, and having
them both land at exactly the same distance.
If that is so, I was obviously wrong in the previous post.

"Laura" wrote in message
...

"Chuck Taylor" wrote in message
...
"Laura" wrote in message
...
Dead on arrival. A dust mote and a rock fall at exactly the same
rate.
(given lack of air and ignoring radiation pressure, solar wind etc).
This
was known to Galileo 400 years ago. It is even taught at school. You
must
have been asleep that day.

Llanzlan


You seem to forget that the inertia of an object is greater the
heavier
it
is.
It makes perfect sense that it takes the earth longer to influence the
path
of a massive object than that of a not so massive one.
They DID teach you about inertia at school, right?

Hi Laura,

If you go up to the top of the leaning tower with Galileo and measure,
you
will find the lightweight ball does not have nearly as much inertia as
the
lead ball of the same size. But when you drop them, even though they
have
different inertia, they still are "influenced" at the same rate and hit
at
the same time.


So, you are saying that a light object moving at high speed, aimed to miss
earth by a small amount (though not close enough to enter the atmosphere),
would be deflected exactly as much by earth's gravity as would a very
heavy
object moving at the same speed?

Correct.


In the leaning tower example, that would be the equivalent of shooting the
two balls out of a cannon, across an airless version of Pisa, and having
them both land at exactly the same distance.

Correct. Given a "Pisa devoid of atmosphere", two cannons pointed in the
exact same direction (say exactly horizontally, for convenience), and the
two balls having the same muzzle velocity, they would hit at exactly the
same distance. If the two muzzle velocities differed, but both cannons were
still pointed exactly horizontally, the two balls would hit at different
distances but at the same time.


If that is so, I was obviously wrong in the previous post.

(Jeff Root) wrote:
Bjørn Sørheim wondered:

- It seems to me that there should be a difference in the angles
(to Earth's horisontal surface/top of atmosphere) which the
path of a meteor (or meteoroid) makes.

And that much larger force is there, according to Newton's law
of gravity. Galileo showed that all bodies accelerate at the
same rate in Earth's gravity. I betcha knew that.

-- Jeff, in Minneapolis

Well, I watched the video from Apollo 15 dropping a feather and a
hammer in no atmosphere just a couple of weeks ago, so I should have
remembered that. Seen it many times anyway.
But I guess I'm more of an experimentalist than theoreticist, so some
theoretical facts may slip my mind, sometimes.

I guess I was thinking of a well, with the shape of the Earth's
gravity field, and doing an experiment with such here on Earth,
complete with the atmosphere. A small wooden/metal ball at a given
speed would have a far greater tendency to fall in to the well than a
larger one, given air resistance.

Anyway, in real life - the atmosphere is there above us - vacuum is
not the norm. Since the atmosphere is extended - it has a thickness of
10 000 km - the smaller particles will be braked, also before they
become visible to us. After they start giving of light they will be
braked even so much more, until the end they fall almost vertically
down. Not so with the large ones, which of course maintain their
speed, angles and bearing (relative to a fixed direction), more so the
greater they are. (As long as they do not go through a terminal blast
at some point before impact, that is.)
So, in real life, on Earth, Venus, Jupiter, Mars etc. the smaller
meteors have a steeper angle - on average - than larger ones at any
point *in the atmosphere*, the only place we observe them!
Not so with the meteoroids outside the atmosphere - you found out -
thank you!
Deep down into the atmosphere, the angle difference between the
smallest and largest meteor, has grown to extremes! The largest
meteors still maintain their initial angles to a great extent.
The 1972 'Teton' fireball is here a good example again. A minute
'average' meteor would never have shown such a behaviour, leaving the
Earth for good again. It would of course have been braked drastically,
and come down as dust particles. So the large ones behave differently!

As my concern really was the average initial angles of large
meteoroids to the atmosphere (or to the Earth's surface, which would
be about the same for the really large ones), I'm more interested in
knowing some reliable figure for the average initial incident angles
for meteoroids, dependent upon mass or not.

Since a very low percentage of them are heading straight at the Earth,
it seems to me that most of them would develop a shallow initial angle
to the atmosphere, especially if the their speed relative to the Earth
is relatively low (but no zero), and taking into account that the
force of gravity grows exponentially with diminishing distance.

Again, any enlightening refs, sites, articles?

OK, I'll promise I'll do a computer simulation later, but I don't have
time right now...

Bjørn Sørheim







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