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

Sunspot update: November most active sunspot month since 2017

My monthly sunspot for December is late this month because I simply forgot to do it. (Thanks to reader Phill Oltmann for prodding my memory.)

Below is NOAA’s monthly graph for tracking the Sun’s monthly sunspot activity, annotated by me to show the past solar cycle predictions.

The increasing sunspot activity we saw in October continued spectacularly in November. In fact, the amount of activity was the most seen since the summer of 2017, when the last solar maximum gave us its last big outburst.

November 2020 sunspot activity

The graph above has been modified to show the predictions of the solar science community for the previous solar maximum. The green curves show the community’s two original predictions from April 2007 for the previous maximum, with half the scientists predicting a very strong maximum and half predicting a weak one. The blue curve is their revised May 2009 prediction. The red curve is the new prediction, first posted by NOAA in April 2020.

November’s activity proves unequivocally that a new solar maximum is coming. We will have no grand minimum this cycle, despite the unprecedented knowledge it would bring us. The sudden increase in November is not unusual during the initial ramp up to solar maximum, but if a grand minimum was coming we would have likely not seen such a burst of activity.

November’s outburst demonstrates again that solar scientists still don’t understand the fundamental processes that cause the Sun’s magnetic dynamo to cycle as it does. In the past decade we have had predictions calling for either a decline in sunspots, a significant increase, or no significant change during this upcoming cycle.

While the middle prediction now appears more correct, it is still too soon to say. As I noted in 2019, “The range of predictions here is so great that essentially it shows that there really is no consensus on what will happen.”

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.

One comment

  • Phill O

    Very interesting November data! There is little question that the early solar spotters would have seen this kind of uptick. The ones in question were the tinny transient sunspots we are now able to observe.

    The upcoming months should give solar dynamicists data for a deluge in papers.

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