Moving at nearly the speed of light, streams of X-ray energy in the far corners of the cosmos are causing tremendous pileups as they ram into slower moving stuff.

News images released this week show energy shooting out of a quasar to encounter just that kind of situation. When the jets shown in the images encounter slower-moving energy, enormously powerful knots of gas form like beads on a string. The images are expected to help scientists learn more about one of the most enigmatic objects in the sky.

Quasars are bizarre objects. When scientists first noticed them in the 1950s and '60s, based on emissions of radio waves, they thought they were strange nearby stars.

But by measuring their redshift -- the change in the wavelength of light emanating from the object based on whether it moves toward or away from us -- astronomers figured out that quasars were billions of light-years away.

That's how they got the name quasar, which is short for quasi-stellar radio sources.

Now quasars are known to be the most distant and powerful sources of energy in the universe. Scientists are only just beginning to understand the dazzling objects, and they are puzzled by the powerful jets of energy that shoot from the cores. How the jets create the knots -- which are like lumpy clouds of gas -- is a complete mystery.

So researchers used the orbiting Chandra X-ray Observatory and other telescopes to study quasar 3C273.

"If there is a slower car in front on a highway, a faster one from behind will eventually catch up and maybe cause a wreck," said MITs Herman Marshall, who headed the study. "If the jet-flow velocity changes, then gas shocks may result, which are akin to car collisions. These gigantic clouds of high-energy electrons, now seen in X-rays with Chandra, may indeed be the result of some sort of cosmic traffic pileup."

Three separate images of the quasar -- in optical, X-ray and radio wavelengths -- each show 10 regularly spaced knots. The first knot produces as much energy as most Seyfert galaxies. No slouches themselves in the energy production department, Seyfert galaxies are thought to be powered by supermassive black holes.

The energy emitted from the quasar's jet probably comes from gas that falls toward the black hole but is redirected by strong electromagnetic fields into the jet, Marshall and his colleagues said. The whole process is poorly understood, but the new images should help researchers learn more.

The findings were presented November 6 at a meeting of the High-Energy Astrophysics Division of the American Astronomical Society in Honolulu.

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