Andromeda Galaxy

I understand it is 2.5 million light yrs away, so we see it as it looked
2.5m yrs ago.

However I understand it is moving towards us, so how far away is it
right now, as opposed to when the light reaching us left the galaxy? I
presume it's been travelling for 2.5 million yrs towards us since the
image we see in telescopes.

Any good guesses?

"Astronomer" wrote in message...
...

I understand it is 2.5 million light yrs away, so we see it as it looked
2.5m yrs ago.

However I understand it is moving towards us, so how far away is it right
now, as opposed to when the light reaching us left the galaxy? I presume
it's been travelling for 2.5 million yrs towards us since the image we see
in telescopes.

Any good guesses?

A good guess would be about 1,000 light years closer.
If you start with Andromeda at 2.5 million light years
away from us now, then 2.5 million years ago that
galaxy was 2,501,000 light years away from us.

This uses the relative velocity between the Milky Way
and the Andromeda galaxies of 120 km/s.

If you don't mind, i'd like to say a couple of things
about all this.

1) Evidently scientists think that the Milky Way and
the Andromeda galaxies will be colliding in 2.5 billion
years. This figure, however, uses a relative velocity
of 300 km/s, which is the relative velocity between
the Andromeda galaxy and our Sun. When the motion
of our Sun and Solar system within the Milky Way
galaxy is taken into account, it is found that the
relative velocity between the Milky Way galaxy and
the Andromeda galaxy is 100 - 140 km/s.

This means that if a collision between the galaxies is
actually to take place, it would happen in 6.25 billion
years, not in 2.5 billion years.

2) Also, you'll note that these relative velocity figures
are those for RADIAL velocity only. The Andromeda
galaxy has not been being observed long enough for
the tangential velocity (side-to-side or lateral velocity)
to be perceptible. So several possibilities exist...

A) The Milky Way and Andromeda galaxies are heading
in opposite directions and toward each other,

B) The galaxies are heading in the same direction and
the Milky Way is leading (this would be like two race
cars on a track--the Andromeda galaxy racer would be
"closing" on the Milky Way car),

C) The galaxies are heading in the same direction and
Andromeda is leading,

D) Because the tangential, side-to-side velocity of the
Andromeda galaxy is unable to be measured, then we
have no way of knowing the true relative vector of the
Andromeda galaxy. The lateral vector could be very
long or very short. So there are any number of
directions that the Andromeda galaxy could actually be
headed (as long as the radial velocity vector stays the
same at 100 - 140 km/s, and the shift remains blue).

I personally like to think that the three main galaxies
in the "Local Group", the Milky Way, the Andromeda
and the Triangulum galaxies, as well as the many tiny
galaxies also in this group, are all revolving around a
common gravitational center. Astronomers believe
that the entire Local Group is traveling together in the
direction of the center of the Virgo cluster, which is the
cluster of galaxies that contains us. And again, to me
it is more likely that the Local Group revolves around
that center, and so is "falling" toward it...

http://www.atlasoftheuniverse.com/localgr.html

happy days and...
starry starry nights!

--
Indelibly yours,
Paine

P.S. Thank YOU for reading!

P.P.S. (shh) Some secret sites...
http://painellsworth.net
http://savethechildren.org
http://eBook-eDen.secretsgolden.com

On Apr 9, 6:15*am, Astronomer wrote:
I understand it is 2.5 million light yrs away, so we see it as it looked
2.5m yrs ago.

However I understand it is moving towards us, so how far away is it
right now, as opposed to when the light reaching us left the galaxy? *I
presume it's been travelling for 2.5 million yrs towards us since the
image we see in telescopes.

Any good guesses?


It is always confusing wherher astronomers are referring to the
distance to the image they see, or the distance to the object's
estimated current location.

Double-A

At those distances it doesn't matter, DA!

The accuracy is not that great. One or two significant figures?
That's all! lmao!

So 2,500,000 lys + or - 100,000 lys. Get it?

Saul Levy


On Thu, 10 Apr 2008 14:46:45 -0700 (PDT), Double-A
wrote:

On Apr 9, 6:15*am, Astronomer wrote:
I understand it is 2.5 million light yrs away, so we see it as it looked
2.5m yrs ago.

However I understand it is moving towards us, so how far away is it
right now, as opposed to when the light reaching us left the galaxy? *I
presume it's been travelling for 2.5 million yrs towards us since the
image we see in telescopes.

Any good guesses?


It is always confusing wherher astronomers are referring to the
distance to the image they see, or the distance to the object's
estimated current location.

Double-A

Double-A I can relate what you posted to being inside a spaceship going
at light speed,and what that would mean,and an outside observer watching
the spaceship coming towards him at 'c'. Its altogether different They
are in reality in to different spacetimes. They are in two different
time zones. They can't relate to each other. Those inside the space ship
could just as well be inside a black hole(not be part of the universe)
Reality is all light coming from stars about 11 billion years ago (Earth
time) could never trace back their source of light go figure Bert

Cactus Saul The best theory I ever read on the universe uses the word
"approximation" Bert

Yes, BEERTbrain, you ARE an approximation! lmao!

Saul Levy


On Fri, 11 Apr 2008 11:12:19 -0400, (G=EMC^2
Glazier) wrote:

Cactus Saul The best theory I ever read on the universe uses the word
"approximation" Bert

Andromeda has twice as many medium size stars in its spiral arms. In 2
million years our spiral arm and Andromeda's spiral arm will merge
together,and humankind by that spacetime will meet Andromed'a's high
life forms. Lets hope they can shake hands Bert

"G=EMC^2 Glazier" wrote...
in message ...

Andromeda has twice as many medium size stars in its spiral arms. In 2
million years our spiral arm and Andromeda's spiral arm will merge
together,and humankind by that spacetime will meet Andromed'a's high
life forms. Lets hope they can shake hands Bert

Bert? Didn't you read my post? Andromeda and the
Milky Way are approaching at about 120 km/sec. This
means that even on the waay outside chance there will
be a collision between the galaxies, it won't be until
6 1/4 billion years from now.

If humankind still exists at that time, they will be living
in another place, because Earth and Sun will be long
gone.

happy days and...
starry starry nights!

--
Indelibly yours,
Paine

P.S. Thank YOU for reading!

P.P.S. (shh) Some secret sites...
http://painellsworth.net
http://savethechildren.org
http://eBook-eDen.secretsgolden.com

On Apr 12, 6:14 am, (G=EMC^2 Glazier) wrote:
Andromeda has twice as many medium size stars in its spiral arms. In 2
million years our spiral arm and Andromeda's spiral arm will merge
together,and humankind by that spacetime will meet Andromed'a's high
life forms. Lets hope they can shake hands Bert

Painius hardly if ever takes into account the elliptical aspects of
such stellar/cosmic interactions, or the increase in closing velocity
as the combined binding force of gravity takes hold.

This is yet another ideal supercomputer simulation, that as such would
leave little doubt as to the future of such cosmic/stellar
interactions. Too bad that our public owned, housed and fully staffed
supercomputers are forever off-limits, as in taboo/nondisclosure
rated.
.. - Brad Guth