Expert: Tom Whiting - 11/22/2005

Question
is this information regarding astronomy true???


As the strong belief of we muslims is that when the
>sun will rise from west
> >rather than east, that time will be the biggest
>identity of The Day Of
> >Judgement (Qayamah). And the door of Forgiveness will
> >be closed on that day.
> >
> >The science of astronomy states that the speed of
>planet Mars has been
> >decreasing in its course towards the eastern
>direction in the few past
> >weeks to the level we notice the "waver" between the
>east and the west..and
> >on Wednesday the 30th of July the planet movement
>stopped going toward the
> >eastern direction..!
> >
> >Then in the months of August and September...Mars
>changed its course in the
> >opposite direction to the West- and
> >that until the end of September..which means the sun
>will rise now from the
> >west
> >on Mars!
> >
> >And thisweird phenomena of the opposite movement
>called "Retrograde
>
> >Motion" Most scientist state that all the planets
>will go through the same
> >once at least and our planet Earth is one of them.
> >
> >Planet Earth will move in the opposite direction some
>day and the sun will
> >rise from the west!


thanks

Answer
Hi there Shaima....and peace be with you....

Well, what you are doing is confusing daily rotation of a planet around its axis (Mars rotates once every 24 hr 37 min, very similar to the Earth) - and this rotation determines the sun rising in the Martian eastern sky all the time, just like on the Earth....not only the sun, but everything
else in the Martian sky, except one Martian moon, which orbits the planet faster than the planet rotates on it's axis-
Phobos orbits the planet Mars in only 7.65 hours, simlar
to one of our artificial satellites - a very strange moon
indeed).......and the only one like that in the Solar System!)

You are confusing rotation,  with orbital revolution, that is the orbit of a planet around the sun.  (and this is where 'retrograde motion' or 'backward motion' comes into play).
(Retrograde motion has nothing to do with axial rotation).

Yes, all astronomers agree that all outer planets exhibit
retrograde motion.....
Ok, retrograde motion occurs when,  say,  we the Earth, pass up and lap an outer planet, which are by definition, traveling slower around the sun then the Earth is....Mars, Jupiter, Saturn, etc...so for a while, that outer planet APPEARS to halt it's eastward motion relative to the distant stars in the night sky, turns around and heads westward with respect to the starry background, (and goes thru opposition as we pass it up-our closest approach to that planet-its at it's brightest and best, like Mars just was on November 7th), then it slowly halts it's westward motion relative to the stars, and resumes its normal eastward motion.

BUT it's NOT a REAL (or true)  motion of the planet, it's only
an "apparent" motion......against the starry sky.
(The planet being overtaken by the Earth has not really
changed direction or speed-it only LOOKS -appears-  like it does, and only relative to the background starry sky.)

An analogy here....
Exactly the same thing happens to you in your car,  passing up another car on a 4 -lane superhighway at 100 Km per hour,
another car which is only doing 95 Km per hour going the same direction.
Surely you've noticed for a moment or two, exactly while you
are passing that car, for a moment that car being passed
APPEARS to be moving 'backward' with respect to the
background farmland or distant desert. That's exactly
what retrograde motion is....us overtaking, in the fast lane,
another slower planet.  (or car on the interstate highway).
See, it's only an 'apparent' motion - not a true motion.
This only happens to an outer planet....so to watch the
Earth appear to retrograde...appear to move backwards (westward) in our night sky,
you would have to be on a planet INSIDE our orbit, namely
only from Venus and Mercury would one see the Earth
'appear to move backwards" relative to the night sky, as
they, Venus and Mercury which are moving much faster
around the sun, overtake and pass (lap-racing term) the Earth.

So see, that's all Mars is doing in our night sky....and it happens every year to every outer planet, and to Mars
every 26 months, as that's how long it takes for the Earth
to overtake, pass, and overtake again, on the next lap. ( Next time will be December 2007 for Mars- every 26 months.)

Opposition occurs always half-way through the retrograde
loop in the sky, as that is exactly when we pass up the
planet...so called opposition because that planet at opposition is exactly opposite the sun in the sky, and thus
the planet rises in the east exactly as the sun is setting in
the west.   And it's when the distance between Earth and
the outer planet is at a minimum.   So it's just a normal thing that's been happening ever since the Solar System formed up some 4.6 billion years ago.

So no, it does not mean that the sun will
"rise in the West" on Mars, as the apparent retrograde
orbital motion around the sun does not change any
true motion of the planet.....and does not affect it's axial
rotation either....the sun will still rise as always, in the east,
on Mars, on time, every day of 24hr 37 minutes.
And of course, the Earth's rotation speed  is unaffected too, as seen from Venus or Mercury.
The sun will always continue to rise in the East....on time,
and on schedule.  Even billions of years from now, when
the Earth slows it's spin rate to that of the moon's orbital revolution around the Earth,
and we face each other the same side, the Earth will still
rotate eastward once every 29 days...but this is some
6 billion years from now.
(But of course the sun is scheduled to enter the Red Giant
Phase in about 3.5 - 4 billion years, so Earth won't be around
to see it).

I can't think of one case where our sun would ever rise
in the west, unless we, the Earth, took a horrible asteroid
strike, that could change the rotational direction, or the axial
tilt severely.  And if that were to ever happen,  the asteroid
impact would be so devastating, we human life forms wouldn't be around long enough to debate it. (or compute
it).
The earth is like a spinning gyroscope  (check the internet
for how stable a spinning gyroscope is)....I've read that if
you took all the world's nuclear arsenal to the North Pole
and exploded it, it would only nudge the Earth's axis the
diameter of one atom....off it's course, and slow the Earth's
rotation rate maybe 1/1000th of a second.  That's how
"locked in" we are, just like a spinning gyroscope.

The Earth travels at about 1000 miles per hour at the
equator, eastward....even faster eastward around the sun....18.5 miles per second.
Again,  I can't even imagine an asteroidal hit that would
change those directions and speeds...unless it would be
a catastrophic hit...in which case, we wouldn't have to
worry about it any more.  We won't be here that long with
that type of asteroid impact.

So now you understand what retrograde motion actually is...
just an apparent view of the outer planets, relative to the night sky,  as we, the Earth,
pass them up just like a racing car....and every astronomer
knows about and actually goes out to observe it...every year
for every outer planet, except Mars is every 26 months,
because we just barely outrun Mars in our race around the
sun.

FURTHER NOTE:  it was this retrograde motion, by the way,
that drove the ancients....Greeks, Ptolomy, Aristotle, etc.
crazy, because they thought it was a TRUE motion of the
outer planets, (not apparent) and that coupled with their mis-belief that the Earth was stationary and everything revolved around the Earth (instead of the sun as we know today)....really got them off to a wrong start in astronomy.
So that's where the ancient 'epicycles' of Ptolomy came from.....they attempted to describe retrograde motion as a true motion, which it would have to be with a stationary Earth, and everything revolving around the Earth.  

Of course, we know today (thanks to science, Copernicus
and Galileo) that all planets orbit the sun,
and it just takes a simple step from there to realize that an
outer planet's backward (westward) motion against the night
sky, is only apparent, (nearly illusionary), and not the planet's true motion around the sun, at all.

Hope all this helps,
Clear Skies,
Tom Whiting
Erie PA  USA


FOLLOWUP INFORMATION:
Oh, by the way, you can actually view and watch the
sunrise and sunset on Mars thru the Rovers eyes...go to
http://marsrovers.jpl.nasa.gov/home/index.html

and you can follow along with the 2 rovers, Spirit and
Opportunity, on the surface of Mars, which have been
operating now for over 600 days.
Down in the lower left hand page, two square blocks show
the time (and it updates every minute) on Mars at the
two sites, nearly opposite each other on the planet.....so if
you time it right, you can actually watch the sunrise on Mars.

Oh, and as far as theological books of the past (Christian
Bible, Quaran, Torah, etc etc) realize they were written
over a thousand years, or more, before humans realized
that the Earth was a spherical, moving planet.
With all those old books, and when they were written, man and humans all believed that the Earth was flat, stationary, non-moving.....they watched
the sun rise, the heavens move above us, each star a fixed
point of light upon a great inverted bowl;  watched the moon
change its shape during each month, and feel that we are
totally at rest on a stationary, flat, solid Earth.....and yet, not
ONE of these things are true.  And the list of deceptions of
nature is a long one....retrograde motion of the slower moving outer planets, is just another deception that nature throws
at us.  It took science to unravel the puzzle, correctly....
so we have to be very careful how we interpret all those
old theological books, because when it comes to science
in general, and astronomy in particular, those books
invariably supply the wrong information if you apply
a literal....word-for-word....interpretation.

I know our own Christian Bible infers in many places, that
the Earth is stationary, everything is revolving around the
Earth....and in a strictly literal sense, that
is an incorrect interpretation.  So that's why I use a
non-literal interpretation, because I realize that the people
back in those days, did not understand astronomy, and the
correct movements of the heavens,  as we do today.
So one has to be very careful in interpreting what our
old theological books, say about science (Big Bang, evolution),  and astronomy.
In almost all cases, a literal interpretation of those books, supplies the incorrect information about those subjects.
Clear Skies,
Tom Whiting
Erie, PA


OH, ADDITIONAL FOLLOWUP:
Even back in the old days before they realized that
retrograde motion of the outer planets was just an apparent movement in the sky,
IF a planet did in fact come to a halt in it's orbit around
the sun, it certainly would not reverse direction and  'move backwards'.....would it?
What would it do if that ever really did happen?  With the sun's strong gravitational field, it would immediately fall.......
directly  into the sun within a few hours!

In fact, that constant orbital speed around the sun is the only thing that keeps all the planets from spiraling down (or falling into) the sun itself.  (A little common sense lesson here).

OH, and with NASA placing a Rover on Mars right into
a 100 meter shallow crater, just where they were aiming for, after a 6 month voyage to Mars, and hit a spot only 100 meters in diameter, then you know that we have to know the
orbital velocity of the both the Earth and Mars, and the
rotational speed of both the Earth and Mars, and the distance
to Mars, to a very high precision, say one part in ten thousand....otherwise,
the spacecraft would have landed way off target on Mars.
But it didn't.
(So we aren't just guessing....we really know-otherwise, our
planetary spacecraft would not be successful.)
Tom