What happens when the poles flip?

Uranus with its moons and rings. Credit: Hubble

Have you heard the startling news that the Earth's poles might flip?

When will this happen? Can this happen?

First, there's no secret planet hurtling through the Solar System causing chaos and orbital disturbances.

So could the Earth spontaneously physically flip over? Some planets have already been tilted and flipped.

Take a look at Uranus. Its orbital tilt is 98-degrees. We assume the planet started with the same tilt as the rest of the Solar System, and some event in the ancient past caused it to fall over.

It could have collided with another planet, billions of years ago, or gravitational interactions with other giant planets pushed it over.

And then there's Venus, its axial tilt is 177-degrees. That's essentially upside down. Venus is turning in the opposite direction from every other planet in the Solar System.

Standing on the surface of Venus, you would see the Sun rise in the West and set in the East. Astronomers don't know why this happened, perhaps it was gravitational interactions or a collision with another planet.

To actually flip a planet off its axis would take an event so catastrophic that it would devastate the planet.

Don't worry, as far as we know, those kinds of events and interactions stopped happening billions of years ago.

Schematic illustration of Earth’s magnetic field. Credit: Peter Reid

The Sun's Heliosphere is about to flip

An artist's concept of the heliospheric current sheet, which becomes more wavy when the sun's magnetic field flips.

Something big is about to happen on the sun.

According to measurements from NASA-supported observatories, the sun's vast magnetic field is about to flip.

Todd Hoeksema

"It looks like we're no more than 3 to 4 months away from a complete field reversal," says solar physicist Todd Hoeksema of Stanford University. "This change will have ripple effects throughout the solar system."

The sun's magnetic field changes polarity approximately every 11 years. It happens at the peak of each solar cycle as the sun's inner magnetic dynamo re-organizes itself.

The coming reversal will mark the midpoint of Solar Cycle 24. Half of 'Solar Max' will be behind us, with half yet to come.

Hoeksema is the director of Stanford's Wilcox Solar Observatory, one of the few observatories in the world that monitor the sun's polar magnetic fields.

The poles are a herald of change. Just as Earth scientists watch our planet's polar regions for signs of climate change, solar physicists do the same thing for the sun.

Magnetograms at Wilcox have been tracking the sun's polar magnetism since 1976, and they have recorded three grand reversals—with a fourth in the offing.

Solar physicist Phil Scherrer, also at Stanford, describes what happens: "The sun's polar magnetic fields weaken, go to zero, and then emerge again with the opposite polarity. This is a regular part of the solar cycle."

A reversal of the sun's magnetic field is, literally, a big event. The domain of the sun's magnetic influence (also known as the "heliosphere") extends billions of kilometers beyond Pluto.

Changes to the field's polarity ripple all the way out to the Voyager probes, on the doorstep of interstellar space.

When solar physicists talk about solar field reversals, their conversation often centers on the "current sheet."

The current sheet is a sprawling surface jutting outward from the sun's equator where the sun's slowly-rotating magnetic field induces an electrical current.

The current itself is small, only one ten-billionth of an amp per square meter (0.0000000001 amps/m2), but there's a lot of it: the amperage flows through a region 10,000 km thick and billions of kilometers wide.

Electrically speaking, the entire heliosphere is organized around this enormous sheet.

During field reversals, the current sheet becomes very wavy. Scherrer likens the undulations to the seams on a baseball.

As Earth orbits the sun, we dip in and out of the current sheet. Transitions from one side to another can stir up stormy space weather around our planet.

Cosmic rays are also affected. These are high-energy particles accelerated to nearly light speed by supernova explosions and other violent events in the galaxy.

Cosmic rays are a danger to astronauts and space probes, and some researchers say they might affect the cloudiness and climate of Earth.

The current sheet acts as a barrier to cosmic rays, deflecting them as they attempt to penetrate the inner solar system. A wavy, crinkly sheet acts as a better shield against these energetic particles from deep space.

As the field reversal approaches, data from Wilcox show that the sun's two hemispheres are out of synch.

"The sun's north pole has already changed sign, while the south pole is racing to catch up," says Scherrer.

"Soon, however, both poles will be reversed, and the second half of Solar Max will be underway."

When that happens, Hoeksema and Scherrer will share the news with their colleagues and the public.

Hot Jupiters: Stars that steal give birth to backwards planets

Stealing gas from their siblings could leave stars with a motley crew of planets – including ones with backwards orbits.

Our solar system is thought to have formed from a collapsing cloud of gas and dust that flattened out as it spun, rather like pizza dough. 

This explains why the planets all orbit the sun in the same direction as the sun itself spins, and share the same plane.

Exoplanets tell a different story, with some tilted at jaunty angles and others orbiting their stars backwards. Planet-on-planet violence is one explanation, but Ingo Thies of the University of Bonn in Germany and colleagues suggest the culprit is the star itself, before its planets are born.

The team made a computer model of stars forming in a cluster. The stars started out forming proto-planetary discs in the usual way. But if a star veered too close to another clump of matter, like another star's disc or a cloud of gas that hadn't formed a star yet, it sucked huge streams of gas – up to 30 times the mass of Jupiter – from its neighbours and into its own nascent disc.

Hot Jupiters

In the model, this stolen material tilted the disc. And when the angle and the mass of material were just right, the final disc ended up spinning in the opposite direction to the star. Any planets that formed in that disc did the same. The work will appear in Monthly Notices of the Royal Astronomical Society.

The influx of gas could also compress the inner part of the disc, making planets form there more quickly. These may be more susceptible to violent crashes, leading to further eccentric orbits.

This in turn could help explain why, unlike our solar system, which keeps the smallest and rockiest planets closest to the sun, many exoplanet systems have bloated gas giants, known as "hot Jupiters", as their innermost planets. When the smaller planets get flung out of the inner part of the disc, an overall conservation of angular momentum means these gas giants could get drawn in closer.

Reference: arxiv.org/abs/1107.2113

Drug that could reverse Alzheimer’s to be tested on patients

A new drug with the potential to halt or even reverse Alzheimer’s disease is expected to be tested in patients later this year, researchers have revealed.

The drug, which tackles a key factor in the development of the disease, is expected to enter the crucial Phase 3 trial – the last stage before seeking regulatory approval – in the latter half of 2010, according to its inventor, Aberdeen University’s Professor Claude Wischik.

Earlier clinical trials of the drug – called remberTM – showed that it could slow progression of Alzheimer’s disease by 84 per cent over 12 months. Furthermore, the effect was sustained over two years. When the results were reported at a conference in Chicago in 2008, they caused worldwide excitement and optimism that, at last, an effective treatment for dementia could be in the pipeline.

But before the drug could move to Phase 3 trials – which will compare it against placebo in larger numbers of patients – millions of dollars in funding have to be raised and regulatory obstacles overcome.

Prof Wischik is optimistic that that ongoing fundraising will permit the Phase 3 trial to begin this year. “This will be a large-scale, international study using around 50 centres,” he said. “We’re moving on substantially from the Phase 2 trial – we’ve beefed up our management team and have really moved on to another level.

“We’re breaking new ground here – the Phase 2 trial provided the first evidence that a drug of this type could arrest progression of the disease, but we believe it can go further than that and perhaps reverse the disease, at least at its early stages.”

The drug acts on the “tangles” which are found in the brains of people with the disease, and which were first described by Alois Alzheimer in 1907. Around two decades ago, Prof Wischik discovered that these tangles were made up of a build up of tau protein, which destroys the brain cells responsible for memory, before going on to kill neurons elsewhere in the brain.

A university spin-out company, TauRx Therapeutics, based in Singapore, developed a novel treatment from a chemical already used in other conditions, which appears to ‘dissolve’ the tangles and halt cognitive decline – the Holy Grail in dementia treatment.

The Phase 2 trial – intended to reveal side-effects as well as efficacy – revealed that the tested form of the chemical worked well at the low and moderate doses, backing the theory that it could arrest the progression of the disease.

It did not work at the highest dose tested due to a problem with the formulation which affected the release of the drug in its active form and this had an impact both on the efficacy and side-effects and limiting the benefit that can be achieved with the older form of the chemical.

Read the full article here at Caledonian Mercury .....