Decentering Earth

Poor Earth!

First it was knocked out of its central location by Copernicus, Kepler, Galileo et al. Now (relatively speaking) comes a popular text called Astronomy Today (Chaisson) that denies its many, probably unique, splendors.

1.1 Our Place in Space

Of all the scientific insights attained to date, one stands out boldly: Earth is neither central nor special. We inhabit no unique place in the universe. Astronomical research, especially within the past few decades, strongly suggests that we live on what seems to be an ordinary rocky planet called Earth, one of nine known planets orbiting an average star called the Sun, a star near the edge of a huge collection of stars called the Milky Way Galaxy, which is one galaxy among countless billions of others spread throughout the observable universe.

But is this true? Is Earth really just an "ordinary rocky planet"? I can think of a number of things that make Earth special. For one thing, amazing luck places it at a distance from the Sun that makes it habitable. The infamous greenhouse effect makes it hospitable and cozy, thanks primarily to water vapor, by far the most important greenhouse gas.* Earth has vast oceans that moderate temperature fluctuations. Goldilock would approve. It has fresh water. It has an atmosphere, and a benign one to boot. Not the poisonous brew of Venus. It has just the right tilt of its axis, held stable by a moon, that gives us our glorious seasons. I mean, its axis could be lying flat on its back like that of Uranus. And we might have 25 years of darkness, alternating with 25 years of relentless sunshine if Earth were Uranus.

*I avoid boiling water to reduce my water vapor footprint.