On Apr 27, 3:53 am, Sanny wrote:
When Sun and Earth are attracting each other why do Earth not fall on
Sun.

When we throw a big Stone in air It will Fall Back on Earth.
Simmilarly For Sun Earth is just a piece of Rock? Who do this big rock
Earth Fall onto the Sun Just like the Stones which we throw in air
just come back and hit the Earth?

Simmilarly why not the Moon fall on Earth by the Gravity attration?

Why are the planets revolving round the sun for so many years instead
of just falling onto the Sun?

When we visit Moon on a Rocket Our Rocket Just Falls on Surface of
moon So why these heavenly bodies not falling on Bigger one?

The moon does fall. It just keeps missing. It has an initial
velocity pointed sideways from the earth. The velocity starts to
change direction toward the earth as it moves sideways. However, the
earth surface has moved downward during this time because it is
round.
The object is falling, in the sense that its path changes
direction toward the other body. However, the surface of the other
body is also changes direction away from the orbiting body. So the
orbiting body is no closer to the surface.
One way to look at it is to ask onself what would happen if the
earth was really flat, rather than round? The moon would still start
falling toward the earth. However, the earth would not be curving away
from the moon. So the moon would eventually hit.
That is why an orbit is called a free fall. It quite literally is
falling. The people in the International Space Station are falling.
But everything is falling at the same rate. So the appearance in the
spaceship is one of weightlessness. The expression "free fall" is more
correct.

Each planet is either orbiting away from the sun or towards it;
it can't be perfectly balanced.. the earth is moving away from the sun.
The moon is moving away from the earth.. X centimeters per year.

Guessing, I'd say the solar system is moving away from Sagittarius A*.
( Sgr A* is at the center of the Milky Way )

On Apr 27, 7:09 pm, wrote:
Each planet is either orbiting away from the sun or towards it;
That is an oxymoron. You can't "orbit away" or "orbit toward"
anything.
it can't be perfectly balanced.. the earth is moving away from the sun. A planet can move in an orbit which with a radius that is slowly increasing or slowly decreasing. A planet can move in a circular orbit that is slowly becoming elliptical, or move in an elliptical orbit that is slowly becoming circular. However, "orbiting away" is nonsense since the orbit has to approximately follow a periodic path. It "can't be perfectly balanced" is another misrepresentation. What can't be perfectly balanced? The gravitational force all by itself can be perfectly balanced. The processes that I mentioned are disturbed by nongravitational forces.
The moon is moving away from the earth.. X centimeters per year.
Due to the frictional forces inside the earth. If gravity alone
were involved, and the earth couldn't deform, even the tidal force
couldn't slow this motion down. Much of the energy in the orbit is
depleted by the water that is deformed into tides. If the earth were
rock solid, all the way down, the motion away from the earth would be
much slower. If the earth were a completely rigid body, the motion
would be slower still. I think gravitational waves would leave the
motion at micromillimeters per second, but I don't know for sure.
Regardless of long term processes that remove energy from the
orbit (thus moving the planet farther), the earth travels in orbits
that are nearly circular or elliptical. Thus, the moon and planets are
moving apart on the scale of hundreds of millions of years.
The question really concerned short term processes. The
comparison to stones falling does not refer to millions of years, the
question concerned why it doesn't fall in our lifetimes. The answer is
that the moon does fall, quickly. However, it has an initial sideways
velocity. The sideways velocity plus the shape of the earth causes the
moon to keep missing.

Guessing, I'd say the solar system is moving away from Sagittarius A*.
( Sgr A* is at the center of the Milky Way )

If the earth's orbit around the sun happened to be slightly higher
it'd be Spiraling Away From the sun ( a bit more each year );
conversely, it'd be spiraling Into the sun.

What are the chances that it'd be doing neither ?
It simply can't be Perfectly balanced.

Oops, I meant to write “ faster �, not “ higher �:
“ If the earth's orbit around the sun happened to be slightly faster
it'd be Spiraling Away From the sun ( a bit more each year );
conversely, it'd be spiraling Into the sun. �.

Oops, I meant to write ? faster ?, not ? higher ?:
? If the earth's orbit around the sun happened to be slightly faster

it'd be Spiraling Away From the sun ( a bit more each year );
conversely, it'd be spiraling Into the sun. ?

Nope. You'd just get a different orbit. Once it gets into a particular
orbit, and no external forces or effects like tides act on it, it'll
stay in the orbit forever.

Thought experiment: Assume a rocket in a perfectly circular orbit around a
planet. The rocket fires momentarily to increase its velocity in the
direction of its motion. What happens? Assuming we don't reach escape
velocity, the rocket will still curve toward the planet but less so than
before. Its velocity will slow as it gets further from the planet (its
potential energy increases, decreasing its kinetic energy) until it
reaches a more distant point, when it stops getting further and starts
"falling" back. It will follow a path to the point where the rocket
fired. At this point it will repeat the path. Plot it and you'll have an
ellipse rather than the original circle.

NASA worked all this out years ago. It also shows a strange contradiction
of orbital mechanics: Try to speed up and you'll slow down (you'll orbit
with a longer period, further from the planet). Conversely, try to slow
down, and (assuming you don't hit the planet) you'll speed up by orbiting
closer and more often.

Spiralling away from the sun (or toward it) would violate conservation
of energy.

There is no need to be "perfectly balanced" other than perfect conditions
necessary to have a perfectly circular orbit. In real life, every bound
orbit is an ellipse, even if it's very nearly a circle.

As you noted, I was wrong,
an orbit stays the same so long as it's below the escape velocity
and away from forces like spinning tides, atmospheric drag, etc.

On Apr 29, 7:20 pm, Jeff$B"%(BRelf wrote:
Oops, I meant to write $B!H(B faster $B!I(B, not $B!H(B higher $B!I(B:
$B!H(B If the earth's orbit around the sun happened to be slightly faster
it'd be Spiraling Away From the sun ( a bit more each year );
conversely, it'd be spiraling Into the sun. $B!I(B.

Okay, the statement is now clear. Now, I can definitely say it is
wrong, which I couldn't honestly say before. If the earths orbit
happened to be slightly faster it would go into another orbit which on
average would be farther from the sun. This orbit would be just as
stable as the orbit is right now. Newton's Law of mechanics have been
used for hundreds of years to calculate orbits.
Two body orbits are quite stable (i.e., earth, sun, and nothing
else). A body can't entirely leave orbit without reaching an escape
velocity. Unless the orbital velocity is very close to the escape
velocity, a small perturbation would result in a small change in
orbit.The earth orbital velocity is no where near the escape velocity
needed to escape from the sun. The fancy way to say it: The earths
orbit is robust against small perturbations.
There are complications with three or more bodies. They are not
always stable over long time frames even without a perturbation.
However, those orbits that are stable will not be destroyed by an
small perturbation.
The orbit slowly increases due to the tides and frictional
forces. As I stated before, gravitational forces alone can't destroy a
two body orbit. Tidal forces are gravitational forces. However,
frictional forces plus gravitational forces can eventually increase
orbital distance.The deformation of the earth by lunar tides generates
a lot of friction. It takes hundreds of millions of years to make a
difference, however.

As you noted, I was wrong, so:
simple orbits don't spiral Away From or Into the sun.

But, 16.5 hours ago, I made the same apology to Michael Moroney:
“ �.

And, 14.5 hours ago, I made the same apology to Saul Levy:
“ �.

Seeing as ( almost ) no one reads anything but direct replies
( if that ), I'll keep repeating myself over and over again.

=?UTF-8?Q?Jeff=E2=96=B2Relf?= writes:

As you noted, I was wrong, so:
simple orbits don't spiral Away From or Into the sun.

But, 16.5 hours ago, I made the same apology to Michael Moroney:

And, 14.5 hours ago, I made the same apology to Saul Levy:

Seeing as ( almost ) no one reads anything but direct replies
( if that ), I'll keep repeating myself over and over again.

Between your lack of quoting relevant portions of posts being replied to
and your constant changing of the subject, your posts often look like
new or unrelated threads to some people. They may not see your replies
in the original thread.