Thank Our Lucky Planets: How Planets Really Do Shape Our Fate

Human history has always been linked to the influence of distant orbits, from climate change (past and present) to our exploration of the solar system.

Solar System

iStockphoto / Pete Draper

Every astronomer has had the annoying experience of being introduced as “an astrologer.” We then have to explain that astronomy is the study of the universe beyond Earth, while astrology is the belief that this universe controls our lives. There’s no good reason to hold that the position of the planets at your birth decided your personality or life path. But it is true that planetary motions have strongly influenced human history and nature.

For several million years, climate changes in Africa repeatedly shaped our evolution. In large part, these climate swings were forced by a complex series of rhythmic oscillations in Earth’s orbit and spin — oscillations that stem largely from the perturbing gravitational influence of Jupiter, Saturn, and the Moon.

Several evolutionary breakthroughs came about during such periods of extreme, modified climate. Upright posture, which freed up our inventive hands; a rapid increase in brain size; and the use of fire, allowing a meat diet that spurred further increase in brain size — scientists have linked all these to episodes of rapid climate alteration. These great leaps forward transformed us from just another species to one with the abilities that enabled the science and technology through which we’ve uncovered our own natural history.

Later we left Africa and peopled the world, our path set by climate-driven changes in sea level such as the one that opened up the Bering Strait land bridge to North America. Seven thousand years ago a phase of stable sea level coincided with the first large coastal settlements and the rise of complex societies. The origin of many sophisticated technologies and the symbolic language to pass them down also seem to have arisen in response to climate-caused survival threats.

Now, in a twist, some of our technology threatens the climate we depend on to survive. Astrology will not save us, but astronomy might. By widening our scope of knowledge and improving our modeling capabilities, planetary exploration is crucial for understanding climate and responding effectively to our current challenges.

Our exploration of the solar system owes its own path to fortuitous planetary positions. Every 175 years the outer planets arrange themselves perfectly for a “grand tour” mission that can ricochet from one gas giant to the next. One such rare alignment came in the 1970s, when we’d just barely developed the necessary technology to launch the pair of Voyager spacecraft. Another important lineup occurred soon after astronomers discovered Pluto’s moon Charon in 1978 (no doubt causing astrologers to redo their charts).

It’s lucky we found Charon when we did. Just two years later, the plane of its orbit lined up precisely with Earth to create a 5-year-long season of Pluto-Charon eclipses. This won’t happen again for more than a century. More importantly, these events and subsequent studies, along with the puzzling nature of Neptune’s moon Triton, seen in Voyager’s final pass in 1989, helped motivate those who agitated for a dedicated Pluto mission, culminating in last year’s historic flyby.

Maybe a species that has colonized its home world would have emerged on Earth even if the solar system didn’t work the way it does. Once here, maybe we were bound to explore our neighboring worlds. But route and timing were dictated from above. The planets have indeed always ruled us.

This article first appeared in print in the November 2016 issue of Sky & Telescope.
Astronomy Blogs, Cosmic Relief with David Grinspoon
David Grinspoon

About David Grinspoon

David Grinspoon, Senior Scientist at Planetary Science Institute, is an astrobiologist who studies the possible conditions for life on other planets. He is also an award-winning science communicator and writer and writes the Cosmic Relief column for Sky & Telescope. His new book Earth In Human Hands was published in December 2016.

3 thoughts on “Thank Our Lucky Planets: How Planets Really Do Shape Our Fate


    Another excursion into pseudo-science by Sky & Telescope that will apparently publish anything for the masses. The conjectural leaps by this author are totally unsubtantiated, especially with regard to evolutionary responses to planetary orbit changes.

  2. Rumpelstiltskin

    We are in the midst of the great clouds of unknowing: where did the universe come from; and where do we go when life as we know it ends. To know the beginning is to know the creator (God) but as God tells Moses, to see my face is your death. Can it be that to die is to know God? Or, as many traditions claim, is it possible that after passing off this mortal coil another body (astral body) can survive and evolve towards the beginning? Astrology is a road map between the unknowns starting from an individual’s landscape. Can astrology guide an individual’s availability for influences that lead to other levels on knowing and unknowing?

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