Astrophysics for People in a Hurry

The world has persisted many a long year, having once been set going in the appropriate motions. From these everything else follows.

What happened before all this? What happened before the beginning?

Planetary atmospheres are rich with such features. And if a planet is teeming with flora and fauna, its atmosphere will be rich with biomarkers—spectral evidence of life. Whether biogenic (produced by any or all life-forms), anthropogenic (produced by the widespread species Homo sapiens), or technogenic (produced only by technology), such rampant evidence will be hard to conceal. (View Highlight)

Our search for life in the universe drives the search for exoplanets, some of which resemble Earth—not in detail, of course, but in overall properties. Latest estimates, extrapolating from the current catalogs, suggests as many as forty billion Earth-like planets in the Milky Way alone. Those are the planets our descendants might want to visit someday, by choice, if not by necessity. (View Highlight)