"The only truly alien planet is Earth."

"Gauss calculated the elements of the planet Ceres and his analysis proved him to be the first of theoretical astronom…"

"Outside intelligences, exploring the solar system with true impartiality, would be quite likely to enter the sun in t…"

"Damn the Solar System. Bad light; planets too distant; pestered with comets; feeble contrivance; could make a better …"

"I am sorry to say that there is too much point to the wisecrack that life is extinct on other planets because their s…"

"It is known that there is an infinite number of worlds, but that not every one is inhabited. Therefore, there must be…"

"The fact that we live at the bottom of a deep gravity well, on the surface of a gas-covered planet going around a nuc…"

"The important achievement of Apollo was demonstrating that humanity is not forever chained to this planet and our vis…"

"I remember on the trip home on Appolo 11, it suddenly struck me that that tiny pea, pretty and blue, was the Earth. I…"

"The fact that this chain of life existed [at volcanic vents on the seafloor] in the black cold of the deep sea and wa…"