Washington: New supercomputer simulations show what the solar system might look like to alien astronomers searching for planets.
The models have also provided a glimpse of how this view might have undergone change as our planetary system matured.
"The planets may be too dim to detect directly, but aliens studying the solar system could easily determine the presence of Neptune - its gravity carves a little gap in the dust," said Marc Kuchner, lead author of the study.
"We`re hoping our models will help us spot Neptune-sized worlds around other stars," he said.
"Christopher Stark of Carnegie Institution for Science said: "Our new simulations also allow us to see how dust from the Kuiper Belt might have looked when the solar system was much younger.
"In effect, we can go back in time and see how the distant view of the solar system may have changed."
Kuiper Belt objects occasionally crash into each other, and this relentless bump-and-grind produces a flurry of icy grains. But tracking how this dust travels through the solar system isn`t easy because small particles are subject to a variety of forces in addition to the gravitational pull of the Sun and planets.
The particles also run into each other, and these collisions can destroy the fragile grains.
"People felt that the collision calculation couldn`t be done because there are just too many of these tiny grains too keep track of. We found a way to do it, and that has opened up a whole new landscape," said Kuchner.
With the help of NASA`s Discover supercomputer, the researchers kept tabs on 75,000 dust particles as they interacted with the outer planets, sunlight, the solar wind -- and each other.
During the simulation, the grains were placed into one of three types of orbits found in today`s Kuiper Belt at a rate based on current ideas of how quickly dust is produced.
From the resulting data, the researchers created synthetic images representing infrared views of the solar system seen from afar.
Through gravitational effects called resonances, Neptune wrangles nearby particles into preferred orbits. This is what creates the clear zone near the planet as well as dust enhancements that precede and follow it around the Sun.
"One thing we`ve learned is that, even in the present-day solar system, collisions play an important role in the Kuiper Belt`s structure," Stark explained. That`s because collisions tend to destroy large particles before they can drift too far from where they`re made.
This results in a relatively dense dust ring that straddles Neptune`s orbit.
Using separate models that employed progressively higher collision rates, the team produced images roughly corresponding to dust generation that was 10, 100 and 1,000 times more intense than in the original model. The scientists estimate the increased dust reflects conditions when the Kuiper Belt was, respectively, 700 million, 100 million and 15 million years old.
As collisions become increasingly important, the likelihood that large dust grains will survive to drift out of the Kuiper Belt drops sharply.
Stepping back through time, today`s broad dusty disk collapses into a dense, bright ring that bears more than a passing resemblance to rings seen around other stars, especially Fomalhaut.
The findings appeared in the Astronomical Journal. (ANI)