Good story telling involves overcoming obstacles.  In sci-fi, those obstacles often include aliens, robots, various anomalies in space or time…  We forget that every cubic light-year of space is full of danger even before we start making stuff up.

Pictured above: our galaxy, the Milky Way.  Part of the image is obscured.  You see those dark clouds?  That’s dust.  Cosmic dust.  Vast clouds of it—enough to block out the stars behind.  Our galaxy is a very dirty place.

If you want to travel anywhere near the speed of light, that dust becomes a huge obstacle.  A collision with a particle smaller than a grain of sand—at high enough velocity—would punch a hole through your ship.  Passing through a cloud of such particles would be like walking into a spray of bullets.

Find that hard to believe?  Think about hitting a deer.  At ten miles per hour, it’s not so bad.  At thirty-five, it’ll probably leave a dent.  At seventy, your car is lucky to be alive.  The greater the speed, the more damage the deer will do.  Now imagine hitting a deer—or anything—at the speed of light, 10 million times faster than any car can go.

With so much dust in our galaxy, the navigators of any interstellar spaceship will spend a lot of stressful hours dodging particles too small to even see.  That, combined with the cosmic radiation from yesterday’s post, makes “empty” space as dangerous as any alien, robot, or space-time anomaly.


Click here for the Iris Nebula, a place where clouds of cosmic dust are clumping together to form new stars.

Click here for some computer simulations of what cosmic dust particles look like at the molecular level.

Click here for a glossary of terms related to cosmic dust and other things found in “empty” space.

3 responses »

  1. Jen says:

    I’ve figured out why I was so confused with this… how does Nasa get around these problems?


    • James Pailly says:

      Good question. The space shuttle, fast as it is, doesn’t travel anywhere near the speed of light. However, you may sometimes hear about small pieces of foam falling off the fuel tank during lift off. At high speed, these bits of foam can and often do damage the shuttle’s hull.
      Collisions with cosmic dust is a bigger problem for spaceships in science fiction, which must travel near the speed of light (or somehow faster) for the sake of telling the story in a reasonable time frame.


  2. […] As you may recall from a previous post, space is dirty.  There are so many particles of dirt floating in space that they block light from many of the stars in our own galaxy.  The researchers found this dirt would accumulate in the compressed space in front of the Enterprise, and when the ship comes to a stop all that dirt would be released as an enormous shockwave.  According to the researchers, this shockwave has enough force to destroy a planet. […]


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