If ET had telescopes no more advanced than ours, would he know our star has planets?
Apparently so, conclude researchers at NASA's Goddard Space Flight Center in Maryland, who built a computer simulation of what our solar system's dust ring looks like from an outsider's perspective.
We have Neptune to thank for our cosmic bootprint. As the planet orbits through the dusty Kuiper Belt region, its gravity perturbs the icy grains, leaving a small, telltale gap, computer simulations show.
"It turns out our solar system has a big bulls-eye of dust in it that ET can see -- if he's got good infrared telescopes," NASA astrophysicist Marc Kuchner told Discovery News.
The study grew out of a Hubble Space Telescope observation of a young star, located 25 light-years away in the constellation Piscis Austrinus, that had a slightly off-centered dust ring. Scientists spent 10 straight hours in 2008 studying the star, known as Fomalhaut. They eventually found a planet in the ring.
"We've been studying debris disks for a couple of years now. People have been looking at them and implying that there are planets perturbing the rings, so we decided to take a look at our solar system," Kuchner said.
The Kuiper Belt region, which extends from the orbit of Neptune, is filled with icy bodies believed to be leftover remains from the solar system's formation. It is similar to debris disks found around other stars, but older, says Kuchner.
As part of the research, Kuchner and colleagues modeled what the Kuiper Belt would have looked like in its earlier days, when it was more densely packed with frozen bodies. Quite often, the objects would crash into each other, producing flurries of ice grains, the study found.
Scientists used a supercomputer to track 75,000 icy particles as they interacted with the outer planes, sunlight, the solar wind and each other.
The team found that the young Kuiper Belt was not like the broad disk that exists today. It appears instead as a dense, bright ring -- a close match to the rings found around other stars, particularly Fomalhaut, says Christopher Stark, an astrophysicist at the Carnegie Institution for Science in Washington, D.C.
The team plans to use the model to simulate debris disks around Fomalhaut and other stars to see if they can detect where planets may be hiding.
They also plan to verify their models with data collected by NASA's New Horizons probe, which will fly by Pluto and other objects in the Kuiper Belt region beginning in 2015.