Leaving Earth cover

In 2019 I obtained from my former publisher the last 30 copies of the now out-of-print hardback of Leaving Earth. I sold about half of these, and with only a handful left in stock I have raised the price. To get your own autographed copy of this rare collector's item please send a $75 check (includes $5 shipping) payable to Robert Zimmerman to

Behind The Black, c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652

I will likely raise the price again when only ten books are left, so buy them now at this price while you still can!

Also available as an inexpensive ebook!

Leaving Earth: Space Stations, Rival Superpowers, and the Quest for Interplanetary Travel, can be purchased as an ebook everywhere for only $3.99 (before discount) at amazon, Barnes & Noble, all ebook vendors, or direct from my ebook publisher, ebookit.


Winner of the 2003 Eugene M. Emme Award of the American Astronautical Society.

"Leaving Earth is one of the best and certainly the most comprehensive summary of our drive into space that I have ever read. It will be invaluable to future scholars because it will tell them how the next chapter of human history opened." -- Arthur C. Clarke

New Horizons shoots a movie

In anticipation of its fly of Pluto next year, the New Horizon spacecraft has produced a 12 frame movie showing Pluto’s moon Charon circling the planet.

Pioneer cover

From the press release: From the moment he is handed a possibility of making the first alien contact, Saunders Maxwell decides he will do it, even if doing so takes him through hell and back.

Unfortunately, that is exactly where that journey takes him.

The vision that Zimmerman paints of vibrant human colonies on the Moon, Mars, the asteroids, and beyond, indomitably fighting the harsh lifeless environment of space to build new societies, captures perfectly the emerging space race we see today.

He also captures in Pioneer the heart of the human spirit, willing to push forward no matter the odds, no matter the cost. It is that spirit that will make the exploration of the heavens possible, forever, into the never-ending future.

Available everywhere for $3.99 (before discount) at amazon, Barnes & Noble, all ebook vendors, or direct from the ebook publisher, ebookit.


  • DK Williams

    What I find really cool about this movie is that you can see Pluto wobble in response to the gravitational tug of Charon as the latter orbits around its host planet. (I refuse to add “minor.) This is readily apparent because the mass of Charon is substantial relative to Pluto. It’s one method (wobble) used to detect extrasolar planets, although I believe the light dimming method is preferred. Bob, please correct me if I’m wrong.

  • Edward

    A couple of decades ago, before extrasolar planets were being discovered, I went to a talk about methods to find them. Each method had its disadvantages.

    Occultation (dimming) required that the target solar system (or at least the planet’s orbital plane) be edge-on to our line of sight. Thus, I was surprised at the large number that Kepler seems to have found.

    Doppler (wobble) would likely find many planets, but their mass would be difficult to determine, as the wobble would be reduced due to the angle of the orbital plane relative to the line of sight. Thus, all that could be determined was a planet’s minimum possible mass.

    Direct observation would have been the preferred method, but the range for distinguishing a planet from its star was short, limiting this method only for nearby stars.

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