April 3, 2020

Review: Many Skies by Arthur Upgren

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It’s a question we all find ourselves asking on occasion. What would our skies look like if things were a little bit different? It’s a fun thought experiment to play; add a Moon here or a Sun there and see what happens. While the night sky may be beautiful, it’s somewhat of a cruel joke that we live out our earthbound existence from but a single vantage point. Perhaps this mediocre position in time and space is why we’re here at all; having lots of active and exotic objects nearby such as supernovae and black holes may not bode well for life.

With Many Skies, Arthur Upgren takes us on an entertaining journey through the realm of astronomical “what ifs.” It’s sobering to think that we’re shackled to our singular Earthly vantage point from which to view the universe. In Many Skies, the author explores different possibilities and the implications of each. What if Earth had multiple (or no) moons? What if we orbited a star system similar to Alpha Centauri? What if the Pleiades and the Hyades switched places? The author lays such a premise at the start of each chapter and then proceeds to explore the ramifications of each in a highly engaging fashion. We often marvel at the things our sky does possess, such as a Moon that can almost exactly cover our Sun during an eclipse in the present epoch. That’s a lucky break, but what wonders must alien skies exhibit? It’s especially fascinating to think how an “alternate sky” would have affected not only astronomy, but our culture and beliefs. Would the exclusive Sun-worshipping cults that later led to monotheism have ever taken root if the ancients had laid witness to several suns? How would our culture and mythos have incorporated a ring around the Earth similar to Saturn, or planets that displayed naked eye phases similar to the Moon?

One fascinating possibility to ponder would be the absence of Earth’s own Moon. How would the evolution of life played out were it not for the ceaseless tides? The complex motion of the Moon also gave early sky ponderers such as Isaac Newton a great study in the physics of gravity. Would we ever have unraveled the riddles of space travel if our planet were “moonless?” The author takes this even further, placing the Earth and Sun as sole intergalactic wanderers in between the galaxies. Do some unfortunate civilizations ponder a largely blank sky, flung far from their galactic nursery and convinced that they’re truly alone? How about those enshrouded in a large dust cloud, or at the heart of a magnificent globular cluster?

The author also takes a look at the modern artificial skies of the 20th and 21st century. Will the ring of satellite debris eventually seed an ablation cascade, breaking down into a great artificial new reef of debris encircling the Earth? What will the ultimate effects of light pollution be not only on our skies but our culture?

The author ends off the book looking at the “most terrifying sky of all” that of the Chicxulub asteroid millions of years ago before, during and after impact.  These are only a few alternate sky scenarios that the author concocts. The book gets the mental juices flowing, as you are encouraged to think up your own alternate reality. The author looks at all of these scenarios with the skilled eye of one who has a true passion for night time observing… I don’t think I’ve ever read such a unique and original work of observational astronomy. We could easily think of more “what ifs” to populate Many Skies II!



  1. [...] we have posed before, worthy of a sequel to Arthur Upgreen’s alternate astronomy book Many Skies; what would Venus look like if it had a moon? As a kid, I remember a science book on the solar [...]

  2. [...] The 2000 book Rare Earth by Peter Ward and Donald Brownlee cites the presence of a large moon as just one of the key ingredients necessary in the story of the evolution of life on Earth. A Moon-less Earth is also just one of the alternative astronomical scenarios cited by Arthur Upgreen in his 2005 book Many Skies. [...]

  3. [...] of the Earth has a fascinating and largely untold history. Arthur Upgren’s outstanding book Many Skies devotes an entire chapter to the possible ramifications of an Earth with multiple moons… sure, [...]

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