Skip to content. | Skip to navigation


I've made my first novel, Ventus, available as a free download, as well as excerpts from two of the Virga books.  I am looking forward to putting up a number of short stories in the near future.

Complete novel:  Ventus


To celebrate the August, 2007 publication of Queen of Candesce, I decided to re-release my first novel as an eBook. You can download it from this page. Ventus was first published by Tor Books in 2000, and and you can still buy it; to everyone who would just like to sample my work, I hope you enjoy this version.

I've released this book under a Creative Commons license, which means you can read it and distribute it freely, but not make derivative works or sell it.

Book Excerpts:  Sun of Suns and Pirate Sun

I've made large tracts of these two Virga books available.  If you want to find out what the Virga universe is all about, you can check it out here:

Major Foresight Project:  Crisis in Zefra

In spring 2005, the Directorate of Land Strategic Concepts of National Defense Canada (that is to say, the army) hired me to write a dramatized future military scenario.  The book-length work, Crisis in Zefra, was set in a mythical African city-state, about 20 years in the future, and concerned a group of Canadian peacekeepers who are trying to ready the city for its first democratic vote while fighting an insurgency.  The project ran to 27,000 words and was published by the army as a bound paperback book.

If you'd like to read Crisis in Zefra, you can download it in PDF form.

Personal tools

The Nearest Exoplanets

It's time for a survey. We can't see them, but we can now calculate how many should be nearby

How many planets are there within 20 lightyears of our sun? Even five years ago we couldn't have answered this question. Today, without actually having spotted any, we can give a fairly confident estimate of how many there should be, and what they should be like. Interested in finding out? Then read on.

The Studies

There's been a lot of commentary in the news in the past year or so about the Kepler mission's cataloguing of distant planets. Kepler has allowed the number of known exoplanets to balloon up past 700 at latest count. Of course, since Kepler is watching a vastly distant patch of sky, it can't tell us how many planets there are in our local neighbourhood. 

A lot has been written about the significance of Kepler's technique, which involves watching for the mini-eclipses that happen when a planet crosses the face of its star. Very little has been written about a parallel hunt that uses microlensing to accomplish a similar end. Microlensing looks for the distortions in the image of a star made by a planet's gravity. These surveys have been going on for ten years now and the results are staggering. 

For instance, did you know that by some estimates there are up to 100,000 nomad planets--planets without a home--for every star in the galaxy? In my 2002 novel Permanence I boldly proposed that there might be one or two brown dwarfs for every star, and that seems to be true; but even in my wildest dreams I couldn't have imagined there might be tens of thousands of planets Pluto-sized or larger drifting between Earth and Alpha Centauri! I still can't really believe it.

These nomads are interesting, because sufficiently large ones (many will be of super-earth size, 2 or more earth-masses) can sustain a trickle of heat from their interiors for billions of years. Though their surfaces may be frozen, they can easily support sub-surface oceans like the one thought to exist in Jupiter's moon Europa. In other words, they can support life. There should be some thousands of these worlds for every star in the galaxy.

This is just the beginning of what the microlensing survey data is showing us. There's enough data now to begin to estimate how many orbiting planets your average star has, and what kind of planets they are. And the combination of microlensing survey data and Kepler data lets us be really precise.

The Numbers

 Kepler's preliminary data seems to indicate that one third of main sequence F, G, and K stars (sunlike stars) have at least one earth-sized planet within the star's habitable zone. There are nineteen such stars within 20 lightyears of us, so this indicates, conservatively, that there are six earth-sized planets in the habitable zone of sunlike stars within 20 light years of Earth

These numbers don't include habitable moons of gas giants that might orbit within the zone. So the actual number could be higher by one or two.

The microlensing survey lets us be precise for the whole population of stars. Here, survey says that the average number of planets per star in our galaxy is 1.6. This leads to the number of bound planets in the galaxy being close to 200 billion, and the number of total planets (including nomads) being ten quadrillion. (There are thus trillions of nomadic super-earths, many of which will have sub-ice oceans capable of developing life.)

The microlensing survey data is so far limited to planets in the super-earth to Jupiter size range, and between .5 and 10 AU distance of their stars. Within those limits, it suggests that 17% of stars have a Jupiter-like planet; 52% have a Neptune-sized planet and 62% have a super-earth. Since the smaller the planet, the more likely it is, we can continue this trend-line to say that in all likelihood, each star will have at least a 62% chance of having an Earth-sized planet. This puts the number of Earth-sized planets in the galaxy at 60 billion or so. The absolute number within 20 light years is at least 42. There's 51 stars outside the main sequence (giants or dwarfs) within 20 light years; another study suggests that the absolute probability for all stars of having a planet within the habitable zone is about 12% (which looks highly conservative). That would add six to our local total, meaning that within 20 light years, there should be at least 12 habitable earth-sized planets. This doesn't count marginal planets, exomoons and Europan worlds. Or, of course, nomads.

To zoom in on a couple of famous local stars, we can say that it's highly unlikely that Alpha Centauri has no planets, given that it is a triple system all of whose stars could support planets. We know Alpha Centauri has no gas giants, but that's consistent with the numbers; but the odds that either Centauri A or B have at least one earth-sized planet within the habitable zone are very high. The Centauris are close to our sun in age, so their planets may still be able to support life.

Tau Ceti, a very sunlike star only 12 light years away, probably has a couple of planets. It's an older star, however, and any earth-sized planets are probably getting arthritic: their plate tectonics will be shutting down somewhere around now. They'll be more like the Barsoom of Edgar Rice Burroughs' Mars novels: ancient and dying.

There's a lot more being discovered and theorized; for instance, one new study suggests that having a Jupiter-like massive planet in your solar system doesn't protect your planet from massive impacts, but on the contrary is a actually bad for you. Another suggests that at least 12% of earth-sized planets have a moon large enough to stabilize their axial tilt (a supposed necessity for planetary habitability) and another suggests that axial tilt won't affect climate all that much anyway. The prospects for life look good around the nearest stars.

The galaxy is literally overflowing with planets, far more than can be crammed into the orbits of its stars. Many of these planets could support life. The question now is, do they?

And if so, where are our nearest neighbours?

Document Actions

Can Voyager find any of them

Posted by Michael Williams at Feb 08, 2012 12:57 PM
I know Voyager is not very far away, yet, but if there are nomadic planets would it be likely that Voyager could detect / find one?
Also, what does this knowledge do to the risk factors of high speed travel( >=.1C, for example)? We know where the stars are, hence we thought we knew where the planets might be, now there are possible unknown obstacles and/or gravity wells in the paths to the nearest stars.
Do we abandon traveling to star systems in the hopes of finding closer nomadic planets instead? How hard are they to find? Are they likely to be traveling the same direction as the rest of the spinning galaxy?
I love this stuff. I don't have any dreams of leaving the Earth (I don't even like to get into airplanes), but it's fun anyway.
Strap on some rockets and bring the nomads into Sol orbit! There's a project to keep us busy for a few thousand years.

Voyager and the Kuiper belt

Posted by Karl Schroeder at Feb 20, 2012 11:36 AM
I don't know whether Voyager would find it any easier to spot these wanderers than a telescope on Earth. The Voyagers were designed to examine nearby worlds, not to look long distance, so it would pretty much have to fly down the throat of one of these worlds to see it, which is pretty unlikely. Similarly, I doubt they'd make much of a navigation hazard: there's probably fewer than 1 per solar-system-volume out there, which is a vast amount of space per object. The chances of even coming close enough to one to notice its gravity are probably infinitesimal. Space, as Douglas Adams said, is big.
Log in

Forgot your password?
New user?
About Me

I'm a member of the Association of Professional Futurists with my own consultancy, and am also currently Chair of the Canadian node of the Millennium Project, a private/public foresight consultancy active in 50 nations. As well, I am an award-winning author with ten published novels translated into as many languages. I write, give talks, and conduct workshops on numerous topics related to the future, including:

  • Future of government
  • Bitcoin and digital currencies
  • The workplace in 2030
  • The Internet of Things
  • Augmented cognition

For a complete bio, go here. To contact me, email karl at kschroeder dot com

Example: The Future of Governance

I use Science Fiction to communicate the results of actual futures studies. Some of my recent research relates to how we'll govern ourselves in the future. I've worked with a few clients on this and published some results.

Here are two examples--and you can read the first for free:

The Canadian army commissioned me to write Crisis in Urlia, a fictionalized study of the future of military command-and-control. You can download a PDF of the book here:

Crisis in Urlia

For the "optimistic Science Fiction" anthology Hieroglyph, I wrote "Degrees of Freedom," set in Haida Gwaii. "Degrees of Freedom" is about an attempt to develop new governing systems by Canadian First Nations people.

I'm continuing to research this exciting area and would be happy to share my findings.


Twitter Updates

    follow me on Twitter
    Mailing List

    Stay informed about new book and story releases, public appearances, readings etc.

    * indicates required
    Coming on June 18, 2019

    "Science fiction at its best."

    --Kim Stanley Robinson

    A Young Adult Scifi Saga

    "Lean and hugely engaging ... and highly recommended."

    --Open Letters Monthly, an Arts and Literature Review

    Sheer Fun: The Virga Series

    (Sun of Suns and Queen of Candesce are combined in Cities of the Air)

     β€œAn adventure-filled tale of sword fights and naval battles... the real fun of this coming-of-age tale includes a pirate treasure hunt and grand scale naval invasions set in the cold, far reaches of space. ”
    β€”Kirkus Reviews (listed in top 10 SF novels for 2006)

    "With Queen of Candesce, [Schroeder] has achieved a clockwork balance of deftly paced adventure and humour, set against an intriguing and unique vision of humanity's far future.
    --The Globe and Mail

    "[Pirate Sun] is fun in the same league as the best SF ever has had to offer, fully as exciting and full of cool science as work from the golden age of SF, but with characterization and plot layering equal to the scrutiny of critical appraisers."

    "...A rollicking good read... fun, bookish, and full of insane air battles"

    "A grand flying-pirate-ship-chases-and-escapes-and-meetings-with-monsters adventure, and it ends not with a debate or a seminar but with a gigantic zero-gee battle around Candesce, a climactic unmasking and showdown, just desserts, and other satisfying stuff."