Seth Shostak Surface Quotations

Every day, the temperature of Sol's surface increases by five billionths of a degree, a change of no consequence for thousands of millennia to come. But a few hundred million years from now, barring a fix by our descendants, this relentless heating will substantially change Earth's biosphere in ways that might not be survivable for us.

What's a space elevator? Simply described, it's a thin ribbon, about 3 feet wide and 60 thousand miles long, stretching upwards from the surface of the Earth. The lower end is bolted to a heavy anchor (think of an oil drilling platform), and the top is capped with a counterweight.

The usual metric for whether a planet is habitable or not is to ascertain whether liquid water could exist on its surface. Most worlds will either be too cold, too hot or of a type (like Jupiter) that may have no solid surface and be swaddled in noxious gases.