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July 5th, 2008, 05:19 AM
Planetary line-up excites the sun


Australian astronomers may have found a solution to how far-away Jupiter and Saturn drive the sun's solar cycle.

In a paper published in the Publications of the Astronomical Society of Australia, astronomer Dr Ian Wilson and colleagues from the University of Southern Queensland, suggest Jupiter and Saturn affect the sun's movement and its rotation, and hence its sunspot activity.

Every 11 years the sun undergoes a period of intense solar activity, marked by flares, coronal mass ejections and sunspots. This period is known as the solar maximum and occurs twice each solar, or Hale, cycle.

July 5th, 2008, 05:21 AM
"The sun can be thought of as a large bar magnet," says Wilson.

"The equatorial region of the sun spins more rapidly than the poles, and this differential rotation winds up the magnetic field lines like a rubber band."

Wilson says sunspots typically appear wherever these magnetic field lines bubble to the surface.

"Once the peak in sunspot activity is reached, a huge amount of energy is released, the magnetic poles are reversed and a new cycle begins," he says.

For many years scientists have recognised an apparent connection between the strength of sunspot activity and the movement of the sun in relation to solar system's barycentre, which is driven by the combined gravitational forces of Jupiter and Saturn.

But no one has been able to explain the connection.

July 5th, 2008, 05:22 AM
The authors believe the tiny gravitational tugs of Jupiter and Saturn speed up or slow down the sun's orbital motion about the centre-of-mass, when they are aligned or separated by an angular distance of 90 degrees.

They say that when the sun's orbital motion changes, so too does its equatorial rotation rate, which provides strong circumstantial evidence that there is a spin-orbit coupling mechanism operating between Jupiter and Saturn and the sun.

The authors propose that this spin-orbit coupling takes the form of a 9:8 resonance, with the 179 year alignment cycle of the Jovian planets being equal to nine alignments of Jupiter and Saturn and eight 22-year Hale cycles.

The extent to which Jupiter and Saturn affect the sun's motion may impact on the strength of sunspot activity throughout its solar cycle.

But Wilson is cautious.

"It is one thing to show an association and quite another to show cause and effect. We have to be very careful, but we will know in a few years," he says.

July 5th, 2008, 05:29 AM

Who knew? Solar system is 'dented,' not round

WASHINGTON (AP) -- When viewed from the rest of the galaxy, the edge of our solar system appears slightly dented as if a giant hand is pushing one edge of it inward, far-traveling NASA probes reveal.

Information from Earth's first space probes to hit the thick edge of the solar system -- called the heliosheath where the solar wind slows abruptly -- paint a picture that is not the simple circle that astronomers long thought, according to several studies published Thursday in the journal Nature.

Surprised astronomers said they will have to change their models for what the solar system looks like.

That push is from the magnetic field that lies between star systems in the Milky Way. The magnetic field hits the solar system at a different angle on the south than on the north, probably because of interstellar turbulence from star explosions, said Voyager project scientist Ed Stone.

July 7th, 2008, 11:48 AM
raise of hands
how many of you have calendars?
how many have calendars
that have a start date and end date??

mayan or axtec

now that is just a calendar
with a start and end day
( i still do not believe a bunch of blood thirsty
savages invented it:pound
but who knows

ps and if they did invent it why a start date of 3114 BC?
that puts the start of this calendar

but FYI

First, when a calendar comes to the end of a cycle, it just rolls over into the next cycle. In our Western society, every year 31 December is followed, not by the End of the World, but by 1 January. So in the Mayan calendar will be followed by - or good-ol' 22 December 2012, with only a few shopping days left to Christmas.


July 7th, 2008, 12:07 PM
I'm curious lighthouse, as to why you keep referring to that ol' Mayan calendar? [It is quite a human achievement, i admit that.]
You posted some nice scientific articles the last days and now you go back to that calendar, why?
And honestly, what's your purpose with this thread, i'm baffled to what you want to achieve with all of what you posted... :idunno

July 9th, 2008, 07:20 AM

Large meteor crosses Israeli skies

A large meteor crossed Israel's skies on Tuesday evening, and was seen by many residents, mainly in the center of the country, Army Radio reported.
A trail left by a meteor ...

According to citizens' reports, the object was seen at approximately 8:15 p.m., as it crossed the sky from east to west horizontally. Some witnesses said they saw two shiny objects in the sky, and others reported that they heard a shrieking sound.

A Petah Tikva resident told Army Radio that he saw a beam of light, which crossed the sky in the direction of the sea. "It looked like a comet, with a long white tail, but much shinier and moving much faster," he said.

Yigal Pat-El, chairman of the Israeli Union of Astronomers, told Army Radio that the meteor was exceptionally large, and that its entry into the atmosphere was not expected



July 9th, 2008, 07:39 AM
solving Kepler's equation is very fast if you start from a good initial guess. If you need the eccentric anomaly for a sequence of times with small dT, then initialising the iteration with the previous solution should converge to machine precision within one or two steps.

The expression for hyperbolic orbits is nearly identical to elliptic orbits. Simply replace sin with hyperbolic sin.

If it helps, here is my code for calculating eccentric anomaly:


double Elements::EccAnomaly (double ma) const
// iterative calculation of eccentric anomaly from mean anomaly

const int niter = 16;
const double tol = 1e-14;
double res, E;
int i;

E = (fabs (ma-priv_ma0) < 1e-2 ? priv_ea0 : ma);
// initial guess for E: use previous calculation or mean anomaly

if (e < 1.0) { // closed orbit: solve M = E - e sin E
res = ma - E + e * sin(E);
if (fabs (res) > fabs (ma))
E = 0.0, res = ma;
for (i = 0; fabs(res) > tol && i < niter; i++) {
E += (max (-1.0, min (1.0, res/(1.0 - e * cos(E)))));
// limit step size to avoid numerical instabilities
res = ma - E + e * sin(E);
} else { // open orbit : solve M = e sinh E - E
res = ma - e * sinh(E) + E;
if (fabs (res) > fabs (ma)) // bad choice of initial E
E = 0.0, res = ma; // last resort
for (i = 0; fabs(res) > tol && i < niter; i++) {
E += (max (-1.0, min (1.0, res/(e * cosh(E) - 1.0))));
// limit step size to avoid numerical instabilities
res = ma - e * sinh(E) + E;

priv_ma0 = ma;
priv_ea0 = E;
return E;


I would think the sun is more than worthwhile you want to accurately display the barycenter.

As the gravitational force on the Moon caused by the Sun is 2.2 times stronger than the one exerted by the Earth, the Moon also orbits the Sun and describes an almost identical ellipse to the one described by the Earth. And its trajectory is always convex: it always curves towards the Sun. That is not the case of the majority of the artificial satellites orbiting the Earth, which make a revolution around our planet in less than 2 hours. But the Moon rotates around the Earth's reference frame 400 times slower.

July 9th, 2008, 07:43 AM
The gravitational pull of the moon is the one single strongest factor in the difference we can see in the level of the oceans between high and low tides, but the Sun's gravitational pull also has a smaller, but still detectable, similar effect.

Similarly, the moon's and the sun's gravitational pulls pull on the earth's crust, and contribute to the effect we now call plate tectonics or tectonic shift.

Further, the gravitational pull of the moon is what is responsible for the fact that the moon does not orbit around the earth, but rather that the earth and the moon both orbit around an invisible point directly between the earth and the moon a few thousand miles above sea level, called the Barycenter, making it that our orbit shifts a few thousand miles closer to or away from the on a monthly basis.

Further, since the moon's orbit around the Barycenter is much larger than the Earth's orbit around the barycenter, the moon passes through a much greater amount of space than the earth does, on each annual orbit around the sun, making it that the vast majority of things floating around in space that could become shooting stars or meteorites or meteors, wind up colliding with the moon instead, making it less likely for the earth to collide with anything that might destroy all life on earth as we know it. So, the moon's gravitational pull helps keep us safe from shooting stars.

July 9th, 2008, 09:23 AM

Do the planets affect the sunspot cycle?

There was a paper published by the Astronomical Journal in April, 1965 ( vol. 70, page 193) by Paul D. Jose which described just such an effect. He noted that the Sun and planets orbit about a point called the barycenter of the solar system which is located between 0.01 and 2.2 times the radius of the Sun from the Sun's center. The path of the Sun is actually a loop-de-loop about this point which doesn't close upon itself like an ordinary planetary orbit. Jose discovered that although this motion is complicated, the Sun returns to roughly its starting position with respect to this point every 179 years, which he noted is 9 times the synodic period of Jupiter and Saturn. This means that every 179 years as seen from the Sun, Jupiter and Saturn return to the same spot in the sky. He looked at the sunspot record from 1610 to 1954 and found evidence of this same period in the maxima and minima of the 11 year sunspot cycle. In other words, superimposed upon the 11-year cycle, there was a 179 year modulation of the amplitudes of each cycle. This modulation matched the phase of the rate of change in time of the Sun's angular momentum (dL/dt) with respect to the barycenter. He concluded that "Certain forces exerted upon the Sun by the planets are the cause of the sunspot cycle"