A tiny, artificial solar system could prove the existence of hidden spatial dimensions and alternative theories of gravity. There are many theories attempting to unify all the forces of physics into one cohesive model which requires the existence of hidden spatial dimensions. According to some, gravity leaks into extra dimensions diluting its power in a 3D unviverse and causing abberations from the standard law of gravity. While this would be noticeable at very small scales, scientists have not been able to accurately measure the force of gravity between closely spaced objects in the lab .

One way of detecting the presence of the hidden dimensions according to Varun Sahni of the Inter-University Centre for Astronomy and Astrophysics (IUCAA) in India, is to send a "solar system in a can" into space. The artificial system would be kept inside a spacecraft about four times as far away from Earth as the Moon known as the Lagrange point.

At the Lagrange point, the artificial solar system would be set in motion inside the spacecraft. A test sphere smaller than the 8-centimetre-wide tungsten sphere (the "sun") will be launched in an oval-shaped orbit 10 cm away. The mini planet would orbit its tungsten sun 3,000 times per year. If the test sphere's movement, changed slightly differently than expected from standard gravity, it could be an indication that gravity is leaking into extra dimensions.

The artificial solar system could also be used to test an alternative theory of gravity, called Modified Newtonian Dynamics (MOND). Acording MOND, gravity starts diverging from Einstein's theory below a certain acceleration. Sahni's team says by placing one or more planets in orbits larger than the one at 10 cm, the slight extra strength of gravity at those larger orbits should make the planets there move faster than predicted under general relativity if the MOND theory holds.

Executing the mini-solar system test is harder than it looks on paper. Cosmic rays, static electricity from charged particles in space, could alter the course of the tiny "planets". Even the spacecraft's components would exert gravitational forces on the spheres. To minimize the effect of these unwanted forces, spacecraft carrying the mini-solar system should be as symmetrical as possible with its heaviest components placed as far from the artificial star system as possible. Although challenging, the experiment was described as not technologically impossible.

Who wants glares in their photographs? Certainly not me and, apparently, not Webster Cash, director of University of Colorado at Boulder Center for Astrophysics and Space Astronomy.

"We would use the starshade as a giant hand to suppress the light emanating from a central star by a factor of about 10 billion," says Cash. He likens the coronagraph to an outfielder holding up one hand to block the sun and get a better view of the ball he is about to catch.

This device is not an entirely new concept. It has and is being used by Sun-watchers for a while now. They block out the main light from the sun giving them a good view of its surrounding. But conventional coronagraphs tend to have light spread out causing a bleeding around the edges. However, the proposed model eliminates this problem by diffracting the light away from the area close to the star, thus, giving us a crystal clear view.

Because the technology needed to make this project into a reality is available, an excited Cash said, "We will be able to study Earth-like planets tens of trillions of miles away and chemically analyze their atmospheres for signs of life."

Like "black holes", neutron stars are the dead cores of massive stars that exploded as supernovae. Their neutrons are packed together so tightly that a teaspoonful of the material would weigh several billion tons.

For years, science has held that matter might be transformed into exotic states in the dense interiors of neutron stars because of the kind of pressures to which matter is subjected. Some believed that neutrons would break down, freeing the individual sub-atomic particles - known as quarks - of which they are made.

Another theory suggests that such pressure might lead to a form of matter known as a Bose-Einstein condensate (BEC) in which neutrons do not break down into quarks. Their individual identities blur, however, as they start to behave as a single particle.

A new analysis of one of neutron stars now indicates that free quarks - never found by themselves in nature - in fact do not come from the cores of these massive bodies.

The old "exotic matter" theories, as they were known, have been disproved in a study by Feryal Ozel of the University of Arizona. An analysis of the mass and radius of a neutron star known as EXO 0748-676, found that it is probably made of ordinary neutrons.

Ozel calculated neutron star's radius to be 13.8 kilometers (about nine miles). Surprisingly, however, its mass came out to over twice that of the sun, suggesting that the star's neutrons are normal. As the mass of a neutron star increases, it becomes more and more rigid. Otherwise, it would collapse into a black hole under its own gravitational force. Most simulations of quark stars and BEC-containing neutron stars predict they would collapse into a black hole before reaching this great a mass.

"I think the physical measurement procedure is sound," says Frits Paerels of Columbia University in New York, US. "The number that comes out of it is interesting. The mass is surprisingly large."

Most neutron stars whose masses have been measured previously are no more than 1.4 to 1.5 times the mass of the Sun - but their actual sizes in terms of volume have been difficult determine, making the nature of the matter inside unclear.

Ozel says the fact that squishy, exotic states of matter do not seem to occur in a star this massive indicates that "exotic states" simply don't exist in these neutron stars.

The Hubble Space Telescope maybe suffering from pink-eye (of sorts) but the Podcasts from Hubble continues. Not really straight from Hubble, but SkyWatch is a weekly conversation highlighting news from the world of astronomy and beyond. You are welcome to eavesdrop via your computer or MP3 player as they bring the latest discoveries down to Earth. In case you haven't heard of Skywatch, here are a few of the recent episodes:

Dwarf Galaxies

Our Milky Way belongs to a cluster of about a dozen galaxies known as the Local Group. New discoveries keep increasing that cluster’s number. Astronomers are finding more of the small dwarf galaxies that hover around our Milky Way. These dwarf galaxies, hidden among the stars, gas and dust of our own galaxy, are difficult to detect. But a new survey of the sky is helping astronomers pick out more of our galaxy’s little companions.

HubbleWatch for June 2006
A comet the size of a city shatters into house-sized fragments under the Sun’s caress. Supernova-sparked gamma ray bursts have the power to fry planets, but don’t panic yet – our galaxy seems an unlikely candidate for such an explosion. Amateur astronomers, break out those telescopes; you can help locate planets beyond our solar system. Jupiter’s renowned Great Red Spot has company – Red Spot Junior, another hurricane-like storm roaring through the atmosphere. Get the details on these topics in this month’s HubbleWatch, your roundup of the latest Hubble Space Telescope science and discoveries.

Amateurs Search for Extrasolar Planets
An international team of professional and amateur astronomers, using simple, off-the-shelf equipment to search the skies for planets outside our solar system, has struck gold. The astronomers discovered a Jupiter-sized planet, named XO-1b, orbiting a Sun-like star 600 light-years from Earth in the constellation Corona Borealis. Using modest telescopes to search for extrasolar planets could create a collaboration between professional and amateur astronomers that would accelerate the quest to find extrasolar planets.

You can listen to these and enough episodes to fill space right here.

"Coronal Mass Ejections" (CME) is the scientific term for a sunstorm, in which huge clouds of superheated gas escape from the sun. These, in turn, cause magnetic storms around the Earth wreaking havoc with terrestrial power grids and doing nasty things to communications satellites. These also have detrimental effects on the health of astronauts (to put it mildly). The ability to predict these storms - and whether a CME will even result in a magnetic storm around Earth - is undoubtedly a good thing, but before now, has been difficult at best.

Using some of the world's fastest supercomputers, researchers at Science Applications International, Inc. of San Diego, California have designed a computer model based on observations of the sun's photosphere - essentially its surface. Magnetic activity here affects the sun's thin outer atmosphere, the corona, where CMEs originate.

This model proved itself earlier this year during the solar eclipse, successfully predicting the shape of the corona. Normally, the corona cannot be observed directly because of the sun's brightness. Despite this, the researchers admit that the ability to accurately predict space weather on a consistent basis is still a decade away, however.