Nearest Star to Earth?

Jo wrote:

Basically it's 'each to their own'...and astronomy is not, and never has
been, one of my interests or whatever! Can any of those who made the smart
arse remarks tell me the content of Brass manufacture for ammunition? At
what rate does a 5.56mm round of ammunition travel in comparison with
7.62mm? What does PDW mean? How many stages of process does it take to
manufacture one round of 5.56mm from start to finish? How many stages of
process does it take to complete one Rarden Shell case? I could go on but i
think you get my point?!!


Thanks for that. The one I didn't know I found via Google and some US
DOD sites.Fascinating. Amazing what a bit of research digs up.

Now to go and shoot out some street lamps.
;-)

Steve

On Fri, 20 Feb 2004 22:48:47 -0000, "Jo" wrote:


"Steve Taylor" wrote in message
. ..
Jo wrote:

Basically it's 'each to their own'...and astronomy is not, and never has
been, one of my interests or whatever! Can any of those who made the
smart
arse remarks tell me the content of Brass manufacture for ammunition? At
what rate does a 5.56mm round of ammunition travel in comparison with
7.62mm? What does PDW mean? How many stages of process does it take to
manufacture one round of 5.56mm from start to finish? How many stages of
process does it take to complete one Rarden Shell case? I could go on
but i
think you get my point?!!

"Steve Taylor" wrote
Thanks for that. The one I didn't know I found via Google and some US
DOD sites.Fascinating. Amazing what a bit of research digs up.

Now to go and shoot out some street lamps.
;-)

Steve

Well just what did you manage to 'dig up' Steve? I don't read much from your
posting in the way of technical information.
Jo


These are astronomy groups, not munitions groups. So don't expect him
to post weapns stuff on this group.

His point, quite apt, was that a quick search of google would have
given you an answer.

Frankly, I'm amazed in this day and age that anyone could be so
uneducated as to be able to use the internet, but still not realise
just what a star is, how far away they are or that space is a vacuum.
Regardless of what their other interests are.

I went to a group of cub scouts. I didn't need to explain to them that
when launching rockets we need to avoid crashing into stars.

Basic understanding of nature and the world around you is one thing
pretty much everyone who has an education in the western world gets, I
would have thought. The same cannot in any way be said for the
manufacturing of weapons.

Your original post suggested that you were asking for a work
colleague.... really, are there two people as dumb as you in the one
place?


--

Find out about Australia's most dangerous Doomsday Cult:
http://users.bigpond.net.au/wanglese/pebble.htm

"You can't fool me, it's turtles all the way down."

On Fri, 20 Feb 2004 15:40:52 -0000, Jo wrote:

Basically it's 'each to their own'...and astronomy is not, and never has
been, one of my interests or whatever! Can any of those who made the smart
arse remarks tell me the content of Brass manufacture for ammunition? At
what rate does a 5.56mm round of ammunition travel in comparison with
7.62mm? What does PDW mean? How many stages of process does it take to
manufacture one round of 5.56mm from start to finish? How many stages of
process does it take to complete one Rarden Shell case? I could go on but i
think you get my point?!!

Are you suggesting that we on the newsgroup think of you as a total ass,
who knows absolutely nothing? No one said you weren't very knowledgeable in
some other field, it's just that some jokers on the group took a chance to
get a laugh out of all this. Some of us tend to think that questions like
yours were supposed to be answered back in elementary school and fall in
line with stuff like "how many planets are there in our solar system?"

We need a laugh on this newsgroup now and then, it'd be very dull
otherwise. I'm sure no one meant you any harm, so try to get over this
whole-non issue. Who knows, sometimes when/if you learn a lot more about
astronomy, you might look back at all this with a good laugh.
At the end, you did learn something new, didn't you?

Cheers.

--
The butler did it.

On Fri, 20 Feb 2004 16:30:27 +0000 (UTC), M Holmes wrote:

In uk.sci.astronomy David Knisely wrote:

The only star we need to worry about avoiding is probably the sun,

We don't have anything wiith the deltavee (*) capability of hitting the Sun
do we?

With chemical boosters?
That would probably depend on what mass you're trying to smash into the
Sun. Either way, 29 km/s isn't a piece of cake, doubt it anyone has
anything capable of this (except ion engines, as John pointed out, but
that's many a month long engine burn :-)

--
The butler did it.

M Holms wrote:

We don't have anything wiith the deltavee (*) capability of hitting the Sun
do we?

Well, probably with a small payload and maybe some gravity assists, we could
get something on a solar impact trajectory using something like a Titan IV.
In fact, there is a concept under development for a spacecraft known as SOLAR
PROBE which would travel on a close-approach trajectory (about 4 solar radii
from the sun) to analyze the composition of the solar Corona and gain
information about the sun at a very close range. Clear skies to you.
--
David W. Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/

**********************************************
* Attend the 11th Annual NEBRASKA STAR PARTY *
* July 18-23, 2004, Merritt Reservoir *
* http://www.NebraskaStarParty.org *
**********************************************

In article ,
burbled happily...

You really have no sense of humour whatsoever, do you?


Yes

Thanks for the confirmation.

Got one thanks....and i'm glad you find me boring as now you wont bother
replying with more smart arse comments.

I just may attempt to teach you how to use your newsreader software as
you seem to be having problems using its quoting ability. Thereagain I
may just conclude you are a trolling muppet and put you back in your
box.
--
Craig Oldfield

In article ,
burbled happily...

Basic understanding of nature and the world around you is one thing
pretty much everyone who has an education in the western world gets, I
would have thought. The same cannot in any way be said for the
manufacturing of weapons.

Your original post suggested that you were asking for a work
colleague.... really, are there two people as dumb as you in the one
place?

More to the point, do they let them near anything dangerous?
--
Craig Oldfield

Craig Oldfield wrote:

They launch during the day,
all the stars are on the other
side of the earth then.

Excellent point Craig. The United States Army's Jupiter C Rocket blasted
off during the night at Cape Canaveral, Florida, bringing our first
United States "Moon" into orbit around Earth in 1958. Because of the
overcast they could not see the stars which repeatedly brought down the
Navy's rockets in the months before.

Hope this helps,
Lou

DON'T FEED THE TROLLS!

In uk.sci.astronomy BenignVanilla wrote:

"M Holmes" wrote in message
...
In uk.sci.astronomy David Knisely wrote:
SNIP
* For Jo: this is just geek talk for change in velocity. The Earth is
whizzing round the Sun at a fair clip and in order for anything lauched
from Earth to hit the Sun, all that speed has to be cancelled so that
the spacecraft can just drop down to the Sun under the Sun's own
gravity. To do that a spacecraft basically has to leave Earth and speeed
up to the Earth's speed, only in the opposite direction so that it's not
moving at all around the Sun. As far as I knwo, we don't have spacecraft
capable of carrying enough fuel to achieve that and so hitting the Sun
is currently impossible without complex gravity assist missions - the
sort of spaceshots which use partial orbits of the other planets in a
sort of cosmic snooker shot.

Oooh....ooh...now this is a cool topic. Splain it more, splain it more.
Would it really take that much energy to get to the sub? I mean it's
gravitational effect holds the planets in place, how much could it take to
get sucked in? You'd just need to close, wouldn't you?

Assuming that you're not trolling here, the answer is basically no. The
Sun is in fact the hardest place in our slar system for a spacecraft to
get to.

I agree that intuitively, it seems like it should be easy. After all, it
has the biggest gravitational pull in the solar system. It's the
gravity, ironically, which makes getting there difficult. The reason has
to do with why orbits are orbits.

A body at rest, such as say you hanging fromn a hot air ballon on a
still day, will in a gravitational field, start down to hit the thing
causing the gravity once it's free to do so, such as when you let go the
balloon. The interesting thing is that there's gravity all the way down.
What this means is that you get to some speed in the first second of
falling, and during that time, gravity is still accelerating you and so
you go even faster in the second second, faster yet in the third second
and so on. In air, eventually air resistance gives you a top speed. In
space there's no air and so you can be falling pretty fast towards
something when you hit it if you started off high enough and it's big
enough to have a significant amount of gravity.

The most interesting thing about orbits is that you fall in them just as
fast as you would if you started off being still. Orbits are a kind of
way of falling to the ground and missing. What you need to be in orbit
is some sideways speed parallel to the ground you're falling towards. So
in that first second, you fall towards the planet or whatever and you
also go a bit sideways because you were already moving abit sideways. If
that sideways movement is just right then you end up falling to and
moving sideways enough so that you're the same height above the planet
as before, just above a slightly different part of the planet. You then
fall and go sideways again and eventually you traverse a circle. Allthe
time though, you're falling towards the planet and missing.

Note that orbits don't have to be circular, they can be elliptical
(oval) but the above still applies in that the sideways movement still
always compensates for the falling bit.

OK, if you haven't died of boredom already, you're thinking "what's this
got to do with not getting to the Sun?".

Well, the Earth is in orbit round the Sun, and seeing as the Sun is
pretty damn big and has a lot of gravity because of that, the Earth has
to go sideways at a pretty fair clip to keep falling into the Sun and
missing.

This is a problem for a would be lander on the Sun (there are oher
problems of course, but they don't apply if you can't even get there).
If a spacecraft takes off from Earth then when it leaves Earth orbit and
goes into orbit around the Sun, it inherits all of the Earth's sideways
speed because asit started on the Earth, it already had it to start
with. We're all moving at 18 miles per second around the Sun right now -
and a bloody good thing too or we'd all be steak by tea time.

So even if the spacecraft has a load of fuel, then just pointing at the
Sun and lighting up won't get it to the Sun. True it'll fall faster
towards the Sun than the Earth, but basically it still has all that
sideways movement that causes it to miss the Sun and all that would
happen is that it'd go into an elliptical orbit around the Sun where the
highest part of the ellipse was still as far away as Earth orbit. It'd
get closerto the Sun at the low part, but unless it loses a lot of that
sideways speed it got from starting at Earth, certainly not close enough
to get there.

Once you work it all out, what you pretty much have to do to get to the
Sun is to get out of Earth orbit and then point the rocket in the
opposite way to all that movement from the Earth and light uyp and head
backwards. If you can cancel all of the sideways movement around the Sun
then the Sun's gravity will take over and you'll go straight down
towards the Sun faster and faster like the guy letting go of the hot air
balloon.

That, in short, is how to get to the Sun.

The trick is that it takes a lot of rocket fuel to cancel 18 miles per
second of speedand to my knowledge, we don'tyet have any rockets which
could come near doing that. Therefore the idea of putting all the
nuclear waste into rockets and dropping it into the Sun will have to
wait.

Hopefully this is clear?

FoFP

--
"Why be politically correct when you can be right?"

-- Geoff Miller