Does a galaxy move?

Perhaps a stupid question but i'm new to astronomy and i would like to know
if a galaxy moves or not and if it moves, how does it move? I mean, the
planets are moving around a sun so does a galaxy move around something or
does it just move because of the big bang or what?

On Wed, 14 Jan 2004 12:24:04 +0000, Passero wrote:

Perhaps a stupid question but i'm new to astronomy and i would like to know
if a galaxy moves or not and if it moves, how does it move? I mean, the
planets are moving around a sun so does a galaxy move around something or
does it just move because of the big bang or what?

Yes, galaxies do move, just as in our solar system where the planets orbit
around our sun, galaxies are in their own orbit. But instead of orbiting
around a star they orbit around the center of the mass of their galactic
group. This is all based on Keplers three laws:

1. The orbit of each planet around the sun is an elipse, with the sun at
one focus.

2. Each planet moves along it orbit so that the radius vector sweeps out
equal areas in equal time.

3. The square of the orbital period of each planet in years equal the cube
of the mean distance from the sun in astronomical units.

Be aware, that due to the distances involved each orbit will be very long,
probably multiples of billions of years.

Now the galactic groups are also moving away from each other due to the
big bang.

Terry

The sun is in orbit around the galactic center it rotates and us along with
it, Edwin Hubble found that all the galaxies are moving away from us.

So everything is moving somewhere.


"Passero" wrote in message
...
Perhaps a stupid question but i'm new to astronomy and i would like to
know
if a galaxy moves or not and if it moves, how does it move? I mean, the
planets are moving around a sun so does a galaxy move around something or
does it just move because of the big bang or what?

"Terry A. Haimann" schreef in bericht
news

Be aware, that due to the distances involved each orbit will be very long,
probably multiples of billions of years.


So our solarsytem does not "stay" at the same place in the univers?
Because of the orbit will be very long, does a galaxy stays at the same spot
at a specific time and place? for example when you look at a galaxy today at
22.30 and you look at the same place but in a few months, will you see the
galaxy or not? Or am i thinking wrong?

Now the galactic groups are also moving away from each other due to the
big bang.

Terry

"Mark F." wrote:

The sun is in orbit around the galactic center it rotates and us along with
it, Edwin Hubble found that all the galaxies are moving away from us.

So everything is moving somewhere.

In general the galaxies are moving away from each other because of the
overall expansion of the universe but at least one galaxy in our 'local
group', M31 'Andromeda', is approaching our Milky Way galaxy at a
velocity of about 125-km/s. If this continues we will collide with M31
in about 4.3-billion years but I wouldn't worry about it. :-)

You can read more about the 'local group' at:

http://nedwww.ipac.caltech.edu/level...er/node16.html


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"Passero" wrote in message
...
Perhaps a stupid question but i'm new to astronomy and i would like to
know
if a galaxy moves or not and if it moves, how does it move? I mean, the
planets are moving around a sun so does a galaxy move around something or
does it just move because of the big bang or what?

You don't see any movement, relative to the stars, within your lifetime.
Galaxies do move; the whole universe is expanding so they are all getting
farther apart. They rotate, too. And there are some other movements,
usually not very well understood.

"Passero" wrote in message
...

So our solarsytem does not "stay" at the same place in the univers?
Because of the orbit will be very long, does a galaxy stays at the same
spot
at a specific time and place? for example when you look at a galaxy today
at
22.30 and you look at the same place but in a few months, will you see the
galaxy or not? Or am i thinking wrong?

You will see a completely different part of the sky because the earth is
orbiting around the sun, so that the night sky (the side of the earth away
from the sun) faces in a different direction at different times of the year.

For example, Orion is high in the sky at midnight in January; in June it
won't be.

But all the stars and galaxies will "move" together (since it's really the
earth that's moving). That's why star maps are possible. You just have to
find out which part of the map is in the sky above you at the time.

While a Galaxy's speed is great, the area is so vast that it just craws along.


--
"In this universe the night was falling,the shadows were lengthening
towards an east that would not know another dawn.
But elsewhere the stars were still young and the light of morning
lingered: and along the path he once had followed, man would one day go
again."

Arthur C. Clarke, The City & The Stars

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"Passero" wrote in message
...

"Terry A. Haimann" schreef in bericht
news

Be aware, that due to the distances involved each orbit will be very long,
probably multiples of billions of years.


So our solarsytem does not "stay" at the same place in the univers?
Because of the orbit will be very long, does a galaxy stays at the same spot
at a specific time and place? for example when you look at a galaxy today at
22.30 and you look at the same place but in a few months, will you see the
galaxy or not? Or am i thinking wrong?

Now the galactic groups are also moving away from each other due to the
big bang.

Terry




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"Passero" wrote in message
...

"Terry A. Haimann" schreef in bericht
news

Be aware, that due to the distances involved each orbit will be very
long,
probably multiples of billions of years.


So our solarsytem does not "stay" at the same place in the univers?
Because of the orbit will be very long, does a galaxy stays at the same
spot
at a specific time and place? for example when you look at a galaxy today
at
22.30 and you look at the same place but in a few months, will you see the
galaxy or not? Or am i thinking wrong?

Everything is in motion. The motion of the local galaxies
with respect to each other is very slow from our point of
view, as the distances are so vast. So you won't see much
difference in locations over a mere matter of months. A
better timescale to watch the motions of the local galaxies
would be using "ticks" of a few million years or so.

Passero wrote:

Perhaps a stupid question but i'm new to astronomy and i would like to know
if a galaxy moves or not and if it moves, how does it move? I mean, the
planets are moving around a sun so does a galaxy move around something or
does it just move because of the big bang or what?

With respect to what? Everything is in motion with respect to something.
There is no absolute motion! There is much evidence that the universe is
expanding (hotter, denser and smallar in the past).

Suggested online resources:
http://www.astro.ucla.edu/~wright/cosmolog.htm
http://www.astro.ucla.edu/~wright/cosmology_faq.html
http://scienceworld.wolfram.com/physics/Velocity.html

Foundations of the Big Bang theory
http://map.gsfc.nasa.gov/m_uni.html

Tests of Big Bang Cosmology
http://map.gsfc.nasa.gov/m_uni/uni_101bbtest.html

-Sam Wormley
http://edu-observatory.org/eo/galaxies.html