A moth-like structure with a 22-billion-mile wingspan is hovering out in space.

This giant is actually a massive cloud of dust surrounding a nearby, young star imaged by the Hubble Space Telescope that has shown astronomers that these dust disks can take on unexpectedly unusual shapes.

Such disks are typically flat, pancake-shaped structures where planets can form. But HD 61005's disk breaks from the norm with a shape dubbed "The Moth". The shape is produced by starlight scattering off the dust.

"It is completely unexpected to find a dust disk with this unusual shape," said senior research scientist Dean Hines of the Space Science Institute in Corrales, New Mexico. "We think HD 61005 is plowing through a local patch of higher-density gas in the interstellar medium, causing material within HD 61005's disk to be swept behind the star."

Hines said that such a collision was unexpected "because the area through which our Sun is moving was evacuated within the past few million years by at least one supernova? Yet, here's evidence of dense material that's very close, only 100 light-years away."

The Moth is part of a survey of sun-like stars that Hines and his colleagues have undertaken with Hubble and NASA's Spitzer Space Telescope to study the formation and evolution of planetary systems.

Astronomers have found evidence that the environment a star forms in can influence the prospects for planet formation around it. But Hines and his team are uncertain how passage through a cloud similar to the one HD 61005 is in would affect planet formation.

"What effect this might have on the disk, and any planets forming within it, is unknown," Hines said.

Hines and his colleagues presented their finding today at a meeting of the American Astronomical Society in Austin, Texas.