when sun dies

When our dear sun will die it will flare up in red gint frying till
earth maybe mars, after that it will end up in white dwarf, is this
mean that gravity of sun will also die off, then what will happen to
outer planets like saturn jupiter ect, will they wander in to deep
space if not end up colliding with other and eventually become planets
of some other sun

George wrote:

When our dear sun will die it will flare up in red gint frying till
earth maybe mars, after that it will end up in white dwarf, is this
mean that gravity of sun will also die off, then what will happen to
outer planets like saturn jupiter ect, will they wander in to deep
space if not end up colliding with other and eventually become planets
of some other sun

The sun will blow off a certain amount of its outer layers, but most of the
mass will remain. The outer planets will remain in orbit, just slightly
larger orbits than at present. That's if we haven't converted them to Dyson
spheres in the meantime.

George wrote:
When our dear sun will die it will flare up in red gint frying till
earth maybe mars, after that it will end up in white dwarf, is this
mean that gravity of sun will also die off,

No, the sun's gravity will not die off. The sun's mass is still in the
same place and where there's mass, there's gravity.

Mike Miller

"George" wrote in message
...
When our dear sun will die it will flare up in red gint frying till
earth maybe mars, after that it will end up in white dwarf, is this
mean that gravity of sun will also die off, then what will happen to
outer planets like saturn jupiter ect, will they wander in to deep
space if not end up colliding with other and eventually become planets
of some other sun

The Andromeda galaxy is coming at us at 300,000 miles an hour. By that time
there will be a galaxy collision that will dwarf the sun dying.
Stars and planets will be flung all over the place.

"Rodney Kelp" writes:
"George" wrote in message
...
When our dear sun will die it will flare up in red gint frying till
earth maybe mars, after that it will end up in white dwarf, is this
mean that gravity of sun will also die off, then what will happen to
outer planets like saturn jupiter ect, will they wander in to deep
space if not end up colliding with other and eventually become planets
of some other sun

The Andromeda galaxy is coming at us at 300,000 miles an hour. By that time
there will be a galaxy collision that will dwarf the sun dying.
Stars and planets will be flung all over the place.

Wikipedia says:

Projections indicate that the Andromeda Galaxy is on a collision
course with the Milky Way, approaching at a speed of about 140
kilometres per second. Impact is predicted in about 3 billion
years; the two galaxies will probably merge to form a giant
elliptical.

(140 km/sec is pretty close to 300,000 mph.) I get about 5 billion
years to impact, but that assumes a constant velocity; presumably
we'll accelerate as we get closer.

I don't think a collision would be nearly as drastic as you suggest.
The stars are far enough apart, at least out here in the outskirts,
that the gravitational effect of one star on its nearest neighbor is
almost always negligible. When the two galaxies start to merge we'll
probably have about twice the current density of stars (but the
nearest star will still be several light years away), with about half
of them having very different velocity vectors. Colliding gas and
dust clouds could create some interesting effects, but probably no
stars will come close enough to disrupt the planets gravitationally.

If Andromeda's core happens to hit near where the Sun happens to be at
the time, things could get bad, but it's a multi-million year process.

I'm curious about one thing. We can measure the approach velocity
accurately via the Doppler shift, but how accurately can we estimate
the lateral velocity? I presume the lateral motion is too small to be
measured directly. Could the motion vectors be such that it will be a
near miss rather than a collision?

--
Keith Thompson (The_Other_Keith) http://www.ghoti.net/~kst
San Diego Supercomputer Center * http://users.sdsc.edu/~kst
We must do something. This is something. Therefore, we must do this.

[I tried posting this earlier but didn't see it appear; trying again
via Google groups.]

In article ,
Keith Thompson writes:
I'm curious about one thing. We can measure the approach velocity
accurately via the Doppler shift, but how accurately can we estimate
the lateral velocity? I presume the lateral motion is too small to
be
measured directly.

Certainly not _easily_ measurable. If the lateral motion is 150 km/s
(similar to radial motion) at a distance of 750 kpc, it is about 40
micro-arcsec per year. This might be measurable with a serious VLBI
program over several years if bright radio sources could be found in
M31 and if their individual motions could be disentangled from the
motion of the galaxy center of mass.

[Since my original posting attempt, I've found out that SIM = Space
Interferometry Mission should be able to measure proper motions with
the needed precision.]

Could the motion vectors be such that it will be a
near miss rather than a collision?

Yes. In fact, that's probably the way to bet. Over enough time,
dynamical friction will cause the M31/Milky Way orbit to decay, and
there will eventually be a collision and merger, but there's no
reason to suppose it will occur during the next periapsis.

--

Steve Willner Phone 617-495-7123

Cambridge, MA 02138 USA
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