Friday, September 24, 2010

An alien's eye view of the solar system (w/ video)

Update: check out our podcast, which features another conversation with Marc Kuchner about his research on colliding planets and the prospects for life in binary star systems.

With help from a supercomputer capable of 67 trillion calculations per second, astronomers at NASA Goddard have determined what our solar system would look like to an alien astronomer. The simulations track the interactions of 75,000 dust grains in the Kuiper Belt, which is an icy region out beyond Neptune where millions of small bodies (including Pluto) orbit the sun.

"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," Goddard astrophysicist Marc Kuchner said in a press release yesterday. "We're hoping our models will help us spot Neptune-sized worlds around other stars."

The images were created from simulations on NASA's Discover supercomputer and are like an infrared snapshot of what the Kuiper Belt would look like from a distant world. What's even more striking is that the images look alarmingly like this Hubble image taken a few years ago of the star Fomalhaut, which shows a planet orbiting inside of what now appears to be a region very similar to our own Kuiper Belt.

Modeling tens of thousands of dust grains in the system was no easy task, and some questioned whether it could be done at all. The astronomers had to account for interactions not just amongst the dust, but also with the outer planets, sunlight and the solar wind.

From the NASA press release

"The size of the model dust ranged from about the width of a needle's eye (0.05 inch or 1.2 millimeters) to more than a thousand times smaller, similar in size to the particles in smoke. 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…

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."

"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," said Christopher Stark, a co-author on the paper.

They've even been nice enough to encapsulate it in an easy to digest form.


  1. The included closed captioning (by NASA?) is really nice.

  2. You think too slow!

  3. 2:18 The Eye!

  4. Billions of years ago...

  5. Why does Neptune make the gap in the dust belt and not Saturn or Uranus? Is it a combination of mass and location?

    Great information by the way, I really enjoyed it.

  6. The appearance of our solar system in the past is important, because the alien astronomers x hundred light years away, will be looking at our solar system as it was x hundred years ago.

  7. Except things don't change much in x hundred years. The time difference between the first two pictures is 3.8 billion years.

  8. Geoff — Yes. The Kuiper belt is on the outskirts of the solar system, and Neptune is the outermost planet.

  9. > The appearance of our solar system in the past
    > is important, because the alien astronomers x
    > hundred light years away, will be looking at
    > our solar system as it was x hundred years ago.

    Boy are they in for a disappointment when they actually arrive here in person.

  10. Why are the orbits circular?

  11. Orbits are ellipses, but not very pronounced ones. Book illustrations are exaggerated.

  12. I like you comment system here, PhysBuzz!