"I really think this came out of orbit," offered Warren Straley, a member of the fivesome and a resident of Manhattan Beach. He once worked as a chief scientist for Hughes Aircraft.

"You know," he added, "there's tons of scrap metal up there."

The object, a solid square of metal with a hexagonal depression in the center and a hole punched through it, measures about 2.5 inches on each side. It weighs almost 2 pounds.

It has been bashed, blunted, scuffed and scarred. Most of it has been burnished to a rock-like dullness, but there are gashes that cut across its surface and lay bare a bright, silvery metal. Raised letters just visible on one side look like two C's.

The sudden arrival of the strange object interrupted the weekly outing of the senior men's golf club of Rolling Hills Covenant Church. The five retirees who gathered around it as it lay in the grass all guessed it came from the sky.

"My first thought was, this had to be a piece of space junk," one of them, Dave Nichols of Torrance, said later.

"It came down hard," said Mac Mc-Cardle, who also lives in Torrance.

"We were just glad that nobody was killed," said Robert Daligney of San Pedro. "It wouldn't even have to hit him in the head."

But while the object may have dropped out of a clear, blue sky, it probably didn't have all that far to drop. Some of its characteristics suggest it had an origin much closer to home than outer space, said Bill Ailor, director of the Center for Orbital and Re-entry Debris Studies at The Aerospace Corporation in El Segundo.

For one thing, it's too heavy. Spacecraft favor lighter materials that are easier and less costly to launch, Ailor said.

Then there are the scratches and machine marks. An object plunging through the atmosphere undergoes more than enough heat to melt steel, leaving it -- if it survives -- much smoother than the chunk that hit the golf course.

Still, Ailor said, objects that seem at first to have come from the heavens often have stories to tell, even when their origins turn out to be entirely terrestrial. Not long ago, a hot piece of metal crashed into a New York apartment. Investigators finally determined it was the overheated brake shoe of a big truck that had blown off.

Ailor reviewed a photograph of the chunk from the golf course. Asked to guess its origins, he said: "It looks like something that came off a heavy truck."

Whatever it is, the object was too hot to pick up when the golfers found it. They had to let it cool in the grass for 10 minutes before they could balance it on a golf ball and carry it to their carts.

And then they finished their round.

"As a matter of fact, that next hole was a mess," said Waddell, who lives on the Palos Verdes Peninsula and came a few feet from getting hit by the object.

"But I don't blame it on that," he added. "The 18th hole was all right."

Discovered in 1998, dark energy seems to percolate out of empty space and provides a repulsive force that is causing the universe to expand at an ever-faster rate.

This is one of the first images taken after the ACS camera resumed science operation on July 4. The camera remained offline for nearly two weeks as NASA engineers switched to a backup power supply after the camera's primary power supply failed.

The picture on the left is of a rich galaxy field containing a distant galaxy cluster 9-billion light-years away (at redshift 1.4).

In a program conducted by Saul Perlmutter of the University of California, Berkeley, Hubble periodically revisits about 20 distant galaxy clusters in an attempt to capture the glow of a class of exploding star called a Type Ia supernova.

Astronomers have directed Hubble to study the clusters because they could reveal the effects of dark energy at a distance too great to be observed easily from the ground.

Type Ia supernovae are bright celestial distance markers that are considered invaluable for measuring how dark energy is influencing the universe. Ultimately, detailed observations like this will allow astrophysicists to understand the nature of dark energy and its influence on the future evolution of the universe more clearly.

When Hubble scanned this field in April 2006, (upper right) the area was dark, but when the telescope revisited the sky coordinates in June 2006, looking at a galaxy about 1-billion light-years closer (redshift 1.2), the supernova appeared.

So, right after ground controllers successfully returned the ACS to operation, they aimed Hubble at the field again to measure the fading stellar explosion (arrow lower right).

The bright core of the host galaxy is adjacent to the glowing supernova, which can briefly become as bright as an entire galaxy of stars.

The quality of the April and July images demonstrate that the ACS is operating perfectly and sending back detailed views of the distant universe, NASA controllers said in a news release.

The object is in the heart of supernova remnant RCW103, the gaseous remains of a star that exploded about 2,000 years ago. Taken at face value, RCW103 and its central source would appear to be a textbook example of what is left behind after a supernova explosion: a bubble of ejected material and a neutron star.

A deep, continuous 24.5-hour observation has revealed something far more complex and intriguing, however. The team, from the Istituto di Astrofisica Spaziale e Fisica Cosmica of the Istituto Nazionale di Astrofisica in Milan, Italy, has found that the emission from the central source varies with a cycle that repeats itself every 6.7 hours.

This is an exceptionally long period, tens of thousands of times longer than expected for a young neutron star. Also, the object's spectral and temporal properties differ from an earlier XMM-Newton observation of this very source in 2001.

"The behavior we see is especially puzzling in view of its young age, less than 2,000 years," said Andrea De Luca of IASF-INAF, the lead author. "It is reminiscent of a multimillion-year-old source. For years we have had a sense that the object is different, but we never knew how different until now."

The object is called 1E161348-5055, which the scientists have conveniently nicknamed 1E (where E stands for Einstein Observatory which discovered the source).

It is embedded nearly perfectly in the centre of RCW 103, about 10 000 light years away in the constellation Norma. The near-perfect alignment of 1E in the centre of RCW 103 leaves astronomers rather confident that the two were born in the same catastrophic event.

When a star at least eight times more massive than the Sun runs out of fuel to burn, it explodes in an event called a supernova. The stellar core implodes, forming a dense nugget called a neutron star or, if there's enough mass, a black hole.

A neutron star contains about a sun's worth of mass crammed into a sphere only about 20 kilometers (12 miles) across.

Scientists have searched for years for 1E's periodicity in order to learn more about its properties, such as how fast it is spinning or whether it has a companion.

"Our clear detection of such a long period together with secular variability in X-ray emission makes for a very weird source," said Patrizia Caraveo of INAF, a co-author and leader of the Milano Group.

"Such properties in a 2000-year-old compact object leave us with two probable scenarios, essentially a source that is accretion-powered or magnetic-field-powered," Caraveo added.

1E could be an isolated magnetar, an exotic subclass of highly magnetized neutron stars. Here, the magnetic field lines act as brakes for the spinning star, liberating energy.

About a dozen magnetars are known. But magnetars usually spin several times per minute. If 1E is spinning only once every 6.67 hours, as the period detection indicates, the magnetic field needed to slow the neutron star in just 2000 years would be too big to be plausible.

A standard magnetar magnetic field could do the trick, however, if a debris disk, formed by leftover material of the exploded star, is also helping to slow down the neutron star spin. This scenario has never been observed before and would point to a new type of neutron star evolution.

Alternatively, the long 6.67-hour period could be the orbital period of a binary system. Such a picture requires that a low-mass normal star managed to remain bound to the compact object generated by the supernova explosion 2000 year ago. Observations do allow for a companion of half the mass of the Sun or even smaller.

1E would be an unprecedented example of a low-mass X-ray binary system in its infancy, a million times younger than standard X-ray binary systems with light companions.

Young age is not the only peculiarity of 1E. The source's cyclic pattern is far more pronounced than that observed for dozens of low-mass X-ray binary systems calling for some unusual neutron star feeding process.

A double accretion process could explain its behavior: The compact object captures a fraction of the dwarf star's wind (wind accretion), but it is also able to pull out gas from the outer layers of its companion, which settles in an accretion disc (disc accretion).

Such an unusual mechanism could be at work in an early phase of the life of a low-mass X-ray binary, dominated by the effects of the initial, expected, orbital eccentricity.

"RCW 103 is an enigma," said Giovanni Bignami, director of CESR,Toulouse, and co-author. "We simply don't have a conclusive answer to what is causing the long X-ray cycles. When we do figure this out, we're going to learn a lot more about supernovae, neutron stars and their evolution."

Had the star exploded in the northern sky, Cleopatra could have seen it and considered it to be an omen of her unhappy end, Caraveo said. Instead the explosion took place deep in the southern sky, and no one recorded it. Nevertheless, the source is a good omen for X-ray astronomers hoping to learn about stellar evolution.