How is it known that the Milky Way is a spiral galaxy ?

wrote in news:1149050310.985264.243480
@y43g2000cwc.googlegroups.com:


Phineas T Puddleduck wrote:
In article .com,
wrote:

Hi,
I'm an absolute newbie
I just wonder how light propagates 13 billion years to hit our retina,
through void, with nothing to prop against?
And as in a crime novel, "cherchez la femme", if you look at the
universe, it's packed with light no matter
where you go, why is light so meaningful to understand the system?

De la discussion jaillit la lumière

Ishke Baha


Light is a self-propagating electromagnetic wave, and unlike sound
waves doesn't need a medium to wave against, per se. Light is a
electric and magnetic wave at right angles to each other, and to the
direction of motion.

The universe is currently dark energy dominated, but was matter
dominated and in the early days was radiation dominated. A quick readup
on the cosmic microwave background would give you a good starter to
cosmology.

--
The true enemy of science is psuedoscience...

Hi,
Light is a self-propagating electromagnetic wave
How can it propagate without consuming energy?

Newton's first law of motion:

Every object in a state of uniform motion tends to remain in that state of
motion unless an external force is applied to it.

As long as the photon doesn't interact with anything else it continues on
its' merry way.

The erroneous belief that things come to rest unless a force is applied,
was debunked by Galileo. A force is required to change the state of motion
as stated by Newton. The source of the error is that we are used to things
being slowed down by mechanical friction, air resistance etc.

I thought there was no such thing as perpetual movement

You thought wrong. You are probably confused with perpetual motion machines
of the first and second kind.

Klazmon.




SNIP

Llanzlan Klazmon wrote:
wrote in news:1149050310.985264.243480
@y43g2000cwc.googlegroups.com:


Phineas T Puddleduck wrote:
In article .com,
wrote:

Hi,
I'm an absolute newbie
I just wonder how light propagates 13 billion years to hit our retina,
through void, with nothing to prop against?
And as in a crime novel, "cherchez la femme", if you look at the
universe, it's packed with light no matter
where you go, why is light so meaningful to understand the system?

De la discussion jaillit la lumière

Ishke Baha


Light is a self-propagating electromagnetic wave, and unlike sound
waves doesn't need a medium to wave against, per se. Light is a
electric and magnetic wave at right angles to each other, and to the
direction of motion.

The universe is currently dark energy dominated, but was matter
dominated and in the early days was radiation dominated. A quick readup
on the cosmic microwave background would give you a good starter to
cosmology.

--
The true enemy of science is psuedoscience...

Hi,
Light is a self-propagating electromagnetic wave
How can it propagate without consuming energy?

Newton's first law of motion:

Every object in a state of uniform motion tends to remain in that state of
motion unless an external force is applied to it.

As long as the photon doesn't interact with anything else it continues on
its' merry way.

The erroneous belief that things come to rest unless a force is applied,
was debunked by Galileo. A force is required to change the state of motion
as stated by Newton. The source of the error is that we are used to things
being slowed down by mechanical friction, air resistance etc.

I thought there was no such thing as perpetual movement

You thought wrong. You are probably confused with perpetual motion machines
of the first and second kind.

Klazmon.




SNIP

Hi,

Newton's first law of motion:

Every object...

So you consider light is an object?

If you study the Meyer Zender interferometer, it would be an object
with a mind of its own?
So an electro magnetic wave is a thinking object?
What message does it carry across the universe?
Blue color would yield spleen, while orange is a symbol for democracy??

And in my hour of darkness, she is standing right in front of me
Speaking words of wisdom,
Let it be

Expert texperts choking smokers
Don't you think a joker laughs at you?

"Jonathan Silverlight" wrote
in message ...
In message , Mike Dworetsky
writes
"Weatherlawyer" wrote in message
roups.com...

When god parted the waters, was this space dust a layer of the watery
deep? God knows. No man alive can say at any rate. The only thing we
can say for certain apparently, is that we still don't have a parallax
on any of the stars yet.


An odd mix of bad theology and even worse science, Sunshine. Never heard
of
the Hipparcos Satellite?


Satellite? They didn't have satellites in the 19th century :-)
I'd guess that a well-equipped amateur could do it, but a quick web
search didn't find any recent examples.

Somewhere at home I have a series of imaged I have taken of proxima
centaurus taken over a number of years. They show sinusoidal movement in
position consistent with propper motion and parallax. It is not very hard to
do and I have pretty basic equipment. (CCD and a VC200L telescope)

Terry B

"Jonathan Silverlight" wrote
in message ...
In message , Mike Dworetsky
writes
"Weatherlawyer" wrote in message
roups.com...

When god parted the waters, was this space dust a layer of the watery
deep? God knows. No man alive can say at any rate. The only thing we
can say for certain apparently, is that we still don't have a parallax
on any of the stars yet.


An odd mix of bad theology and even worse science, Sunshine. Never heard
of
the Hipparcos Satellite?


Satellite? They didn't have satellites in the 19th century :-)
I'd guess that a well-equipped amateur could do it, but a quick web
search didn't find any recent examples.

An article in (I think) Feb 2006 Sky & Telescope is by an amateur who
measured the parallax of a newly discovered high-proper-motion star, using
amateur equipment. +/- one month on that memory...

--
Mike Dworetsky

(Remove "pants" spamblock to send e-mail)

"Weatherlawyer" wrote in message
ups.com...

Mike Dworetsky wrote:

When god parted the waters, was this space dust a layer of the watery
deep? God knows. No man alive can say at any rate. The only thing we
can say for certain apparently, is that we still don't have a parallax
on any of the stars yet.


An odd mix of bad theology and even worse science, Sunshine. Never
heard of
the Hipparcos Satellite?

Rewind we. Is that the one they fired a slug into a snow cloud from? Or
would you prefer it called an asteroid?


No. This was the one used to observe high precision stellar positions,
motions, and parallaxes for around 100,000 stars. You have just claimed it
couldn't be done.

For someone who likes to make wild claims and pronouncements, you don't
actually seem to know anything at all about the subjects.

You can call it the hemmaroid of god if you like for what the
difference was. It seemed very biblical to me, oh troll of very little
brain.


Ignorance in a normal person can be cured by education. Yet no amount of
education will help the wilfully ignorant, or the just plain stupid.

--
Mike Dworetsky

(Remove "pants" spamblock to send e-mail)

In article om,
Weatherlawyer wrote:

Phineas T Puddleduck wrote:

Light is a self-propagating electromagnetic wave, and unlike sound
waves doesn't need a medium to wave against, per se. Light is a
electric and magnetic wave at right angles to each other, and to the
direction of motion.

What light might be, remains to be seen (to coin a phrase.) I would
have considered it a measure of the power of heat in some way but how
can you say it is en example of elecromagnetic wave?

Get real. Something is either moving or the path it takes has
undulating features it can not "be" both.


Wow

You really are truly clueless about physics. If you want proof of the
wave nature of light, and the early beginnings of relativity - I
suggest you read up a little on Mr Maxwell and his equations - then
"get real" yourself.

--
The true enemy of science is psuedoscience...

In article .com,
wrote:


Hi,
Light is a self-propagating electromagnetic wave
How can it propagate without consuming energy?
I thought there was no such thing as perpetual movement

As explained by others, an object CONTINUES on its motion....

currently dark energy dominated
So when electromagnetic waves travel 4 billion years through o.k. void,
what happens when they enter dark energy territory?


The distinctions are time, not location based....

--
The true enemy of science is psuedoscience...

In article . com,
Weatherlawyer wrote:


Rewind we. Is that the one they fired a slug into a snow cloud from? Or
would you prefer it called an asteroid?

You can call it the hemmaroid of god if you like for what the
difference was. It seemed very biblical to me, oh troll of very little
brain.

Visits to nasa.gov and esa.int would do wonders for your (lack of)
education re modern astronomy. Perhaps some elementary reading on 20th
century physics too...

--
The true enemy of science is psuedoscience...

Phineas T Puddleduck has:
Catagorical and irrefutable proof that

Light is a self-propagating electromagnetic wave, and unlike sound
waves doesn't need a medium to wave against, per se. Light is a
electric and magnetic wave at right angles to each other, and to the
direction of motion.
WetherLawyer on the other hand:
Disputes this on the grounds that something can't be the pilgrim and
the sojourn thus

Get real. Something is either moving or the path it takes has
undulating features it can not "be" both.
Phineas T Puddleduck having:
Accepted by default the laws of motion propounded elsewhere in this
thread emiited
Wow

You really are truly clueless about physics. If you want proof of the
wave nature of light, and the early beginnings of relativity - I
suggest you read up a little on Mr Maxwell and his equations - then
"get real" yourself.

--
The true enemy of science is psuedoscience...

Define science, clot.
(But keep it to yourself. You have lost my attention.)

Mike Dworetsky wrote:

This was the one used to observe high precision stellar positions,
motions, and parallaxes for around 100,000 stars. You have just claimed it
couldn't be done.

Not quite.

I was informed that parallax had yet to be determined for any stars in
a thread some weeks back.

Obviously I should have kept up to date in the intervening weeks.