Of all the science accomplished since Renaissance times, one result stands out most boldly: Our planet is neither central nor special. Application of the scientific method has demonstrated that we do not inhabit a unique place in the Universe. Research, especially within the past few decades, strongly suggests that we live on what seems to be an ordinary planet called Earth, one planet orbiting an average star called the Sun, one Solar System in the suburbs of a much larger group of stars called the Milky Way Galaxy, one galaxy among countless billions of others spread throughout the observable abyss called the Universe.
The Universe can be defined as the vast tracts of empty space and enormous stretches of time populated sparsely by stars and galaxies glowing in the dark. More succinctly, the Universe is the totality of all space, matter, and energy.
The irresistible, mind-boggling fantasy comes to just about everyone, sooner or later: What if everything we knew, our whole universe, was just a speck of dust on someone's shoulder? ...
On Earth, children have two parents. In space, though, it's more common for a planet to be born and grow up with just one "parent": the star it orbits. ...
