Image: Kuiper Belt
NASA/Goddard/Marc Kuchner and Ch
These images, produced by computer models that track the movement of icy grains, represent infrared snapshots of Kuiper Belt dust as seen by a distant observer over time.
updated 9/30/2010 1:08:28 PM ET 2010-09-30T17:08:28

Alien astronomers searching for planets in our solar system would at least be able to see Neptune inside the dusty disk that surrounds our planetary neighborhood, a new study suggests.

The method used in the study could be a new tool for astronomers on Earth seeking out strange new worlds, since the dust rings around other stars could be used to find their outer planets, too.

Our solar system has one of these dust clouds out beyond the orbit of Neptune, researchers said.

The new study models how our sun's dust cloud formed and evolved as our solar 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," study leader Marc Kuchner, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Md., said in a statement. "We're hoping our models will help us spot Neptune-sized worlds around other stars."

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A haze of dusty debris
Much of our solar system's dust originates in the faraway Kuiper Belt, a cold-storage zone beyond Neptune where millions of icy bodies including the dwarf planet Pluto orbit the sun. Scientists think the region is an older, leaner version of the debris disks they've seen around distant stars like Vega and Fomalhaut.

Kuiper Belt objects sometimes crash into each other, producing a flurry of icy grains, the researchers said. This dust moves about, jostled by a variety of forces.

There's the gravitational tug of the sun and planets, for starters. And the solar wind the stream of charged particles flowing from the sun can work to bring dust closer to the sun, researchers said. Sunlight can either pull dust inward or push it outward, depending on the size of the grain. The particles also run into each other, and these collisions can destroy the fragile grains.

So tracking the dust is a challenge.

"People felt that the collision calculation couldn't be done because there are just too many of these tiny grains to keep track of," Kuchner said. "We found a way to do it, and that has opened up a whole new landscape."

The scientists reported their findings in the Sept. 7 edition of The Astronomical Journal. NASA announced them Sept. 23.

Solar system in a supercomputer
Using NASA's Discover supercomputer, the researchers kept tabs on 75,000 simulated dust particles as they interacted with the outer planets, sunlight, the solar wind and each other.

The size of the model dust ranged from about the width of a needle's eye (0.05 inches or 1.2 millimeters) to less than a thousandth of that size, about as large as the particles in smoke. From the resulting data, the researchers created synthetic images representing how the solar system looks from afar, in infrared light.

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They found that Neptune's gravity wrangles nearby dust particles into preferred orbits, creating a clear zone around the planet.

Astronomers on Earth might be able to spot alien planets by searching for such dust gaps in distant star systems, the researchers said.

Going back in time
The researchers also modeled the dust cloud's appearance at various stages in the past. The Kuiper Belt used to hold many more objects that crashed together more frequently, the researchers said, generating dust at a faster pace.

So the team sped up their models' dust-production rates to reflect conditions of the Kuiper Belt when it was 15 million years old, 100 million years old, and 700 million years old.

Today the Kuiper Belt, like the solar system itself, is about 4.6 billion years old.

"We were just astounded by what we saw," Kuchner said.

With more dust, collisions occur more frequently, and the likelihood that large grains would survive to drift out of the Kuiper Belt dropped sharply, the researchers said.

Stepping back through time, today's broad dusty disk collapses into a dense, bright ring, which looks a lot like the rings seen around some other stars, especially Fomalhaut.

Fomalhaut is a young star about 25 light-years from Earth; astronomers have confirmed that at least one planet circles the star.

"The amazing thing is that we've already seen these narrow rings around other stars," said study co-author Christopher Stark of the Carnegie Institution for Science in Washington, D.C. "One of our next steps will be to simulate the debris disks around Fomalhaut and other stars to see what the dust distribution tells us about the presence of planets."

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Photos: Month in space: September 2010

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  1. Martian sea of sand

    Near Mars' north pole, the landscape is dominated by sand dunes forming a massive erg, or sand sea, much like parts of the Sahara Desert on Earth. In parts of the erg, sand is abundant and covers the entire surface. Here, near the edge, sand is in shorter supply and the dunes are separated by areas of lighter-toned soil. This color-coded image from NASA's Mars Reconnaissance Orbiter was captured in July and published on Sept. 1. (NASA /JPL/ University of Arizona) Back to slideshow navigation
  2. Dance of the galaxies

    NGC 5426 and NGC 5427 are two spiral galaxies of similar sizes engaged in a dramatic dance. It is not certain that this interaction will end in a collision and ultimately a merging of the two galaxies, although the galaxies have already been affected. Together known as Arp 271, this dance will last for tens of millions of years. This image, released Aug. 30, was taken with the EFOSC instrument attached to the New Technology Telescope at the European Southern Observatory's La Silla facility in Chile. (ESO) Back to slideshow navigation
  3. Crazy cones on Mars

    These Martian volcanic cones are similar in size and shape to cones found in Iceland, where hot lava has run over wet ground. The heat from the lava boils the water, which bursts through the lava flow. These steam-driven exploding bubbles of lava throw chunks of molten and solid lava into the air. A long series of such explosions is needed to build up one of the large cones. This image, released Sept. 1, was taken by a high-resolution camera on NASA's Mars Reconnaissance Orbiter. (NASA via AP) Back to slideshow navigation
  4. Creating Curiosity

    Engineers work on the Curiosity rover at NASA's Jet Propulsion Laboratory in Pasadena, Calif., on Sept. 16. Curiosity, also known as the Mars Science Laboratory, is due to be launched to the Red Planet from Cape Canaveral Air Force Station in Florida in late 2011. (Jae C. Hong / AP) Back to slideshow navigation
  5. Igor the Terrible

    A photo taken from the International Space Station on Sept. 15 shows Hurricane Igor whirling through the Atlantic Ocean hundreds of miles below. In the foreground you can see a Russian spacecraft docked to the space station. (NASA via AFP - Getty Images) Back to slideshow navigation
  6. Dodging a bullet

    An extreme ultraviolet image from NASA's Solar Dynamics Observatory shows an exceptionally heavy plasma eruption on the surface of the sun on Sept. 8. Not to worry, though: The resulting blast of electrically charged particles missed Earth. (NASA/SDA via EPA) Back to slideshow navigation
  7. Bull's-eye on the moon

    A color-coded topographic map based on data from NASA's Lunar Reconnaissance Orbiter shows the 580-mile-wide Mare Orientale, the largest young impact basin on the moon. This basin formed when a projectile hit the moon about 3.8 billion years ago and penetrated deeply into the lunar crust, ejecting huge amounts of material. The image was released Sept. 16 to coincide with the publication of scientific papers about LRO's mission. (NASA / Goddard / MIT / Brown) Back to slideshow navigation
  8. Two flashes from Jupiter

    A fleeting bright dot on each of these images of Jupiter marks a small comet or asteroid burning up in the atmosphere. The image on the left was taken on June 3 by Australian amateur astronomer Anthony Wesley, with a fireball appearing on the right side. The image on the right was taken by Japanese amateur astronomer Masayuki Tachikawa on Aug. 20, with a fireball appearing at upper right. In a report published Sept. 9, NASA said neither event left a lasting mark on the planet. (NASA via Reuters) Back to slideshow navigation
  9. Spiral in space

    A picture from the Hubble Space Telescope, published Sept. 7, shows an unusual spiral nebula around the star LL Pegasi, 3,000 light-years from Earth. Astronomers say the spiral shape was created by material swirling out from one of the stars in a binary-star system. (ESA / NASA) Back to slideshow navigation
  10. Bootprint on Mars?

    Orcus Patera is an enigmatic elliptical depression near Mars' equator, in the eastern hemisphere of the planet. Located between the volcanoes of Elysium Mons and Olympus Mons, its formation remains a mystery. The favored theory is that the feature was created when a comet or asteroid hit the Red Planet at a shallow angle. This picture of Orcus Patera, released Aug. 27, was taken by the European Space Agency's Mars Express orbiter. (ESA) Back to slideshow navigation
  11. NASA's six-legged robot

    The All-Terrain Hex-Limbed Extra-Terrestrial Explorer, or ATHLETE, is a prototype heavy-lift utility vehicle designed to support future human exploration of extraterrestrial surfaces. ATHLETE got a chance to flex its limbs on Sept. 15 in northern Arizona during NASA's Desert RATS field tests. (Robyn Beck / AFP - Getty Images) Back to slideshow navigation
  12. Practicing for Mars

    Geologists Jacob Bleacher and Jim Rice take a close look at a rock formation in northern Arizona before collecting samples on Sept. 5. The geologists took part in NASA's Desert RATS exercise, which is aimed at trying out the equipment and procedures that could come into play during a mission to Mars or other interplanetary destinations. The "RATS" in the name stands for "Research and Technology Studies." (NASA Desert RATS) Back to slideshow navigation
  13. Ice sculptures in space

    Clouds of gas and dust in the Carina Nebula are sculpted into bizarre shapes by stellar radiation, as seen in this image captured by the Hubble Space Telescope and unveiled on Sept. 16. The Hubble team compares the pillars to "cosmic ice sculptures." (NASA, ESA, and the Hubble Heritage Project) Back to slideshow navigation
  14. New York at night

    New York City is ablaze in an image sent by NASA astronaut Doug Wheelock from the International Space Station on Aug. 28. "The City That Never Sleeps," he wrote in a Twitter tweet. "New York, New York on a clear summer night." (Doug Wheelock / NASA via AP) Back to slideshow navigation
  15. Shooting a laser at the sky

    This image, released on Sept. 6, shows a laser beam shooting up from the European Southern Observatory’s Paranal Observatory in Chile. The laser beam is used as a guide for the observatory's adaptive-optics system, which compensates for unsteadiness in the atmosphere to produce sharper astronomical images. (Y. Beletsky / ESO) Back to slideshow navigation
  16. Thar she blows!

    A solid rocket motor that could be used on future NASA launch vehicles is tested Aug. 31 at ATK Aerospace Systems' test site in Promontory, Utah. The rocket motor burned for just over two minutes during the successful static test, producing about 3.6 million pounds of thrust. (ATK) Back to slideshow navigation
  17. The road ahead

    NASA's Opportunity rover looks across a series of sand ripples and bedrock outcrops toward the rim of Endeavour Crater on the horizon on Sept. 6. Opportunity has just crossed the halfway mark in its trip from Victoria Crater to Endeavour. The rover headed out from Victoria in September 2008. (NASA / JPL-Caltech) Back to slideshow navigation
  18. Saturn and its children

    Four of Saturn's moons join the planet for a well-balanced portrait, released by the Cassini orbiter's imaging team on Sept. 10. Saturn's largest moon, Titan, is at lower left. Tethys is at upper right. Two much smaller moons, Pandora and Epimetheus, are barely visible near the rings. (NASA/JPL/Space Science Institute) Back to slideshow navigation
  19. Moon and Earthglow

    A crescent moon is just about to set below Earth's glowing horizon in a picture taken Sept. 4 from the International Space Station. The glow is sunlight scattered by Earth's atmosphere. (NASA via Reuters) Back to slideshow navigation
  20. Twilight of the shuttle

    Photographers gather early on the morning of Sept. 21 to take pictures of the space shuttle Discovery, just after its arrival at the launch pad. Discovery is scheduled to embark on the shuttle fleet's penultimate mission on Nov. 1. The final shuttle flight, involving Endeavour, is set for launch in February - although there's a chance that one additional mission will be flown. (Scott Audette / Reuters) Back to slideshow navigation
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