Unafraid of the empty wastes

Let us create vessels and sails adjusted to the heavenly ether, and there will be plenty of people unafraid of the empty wastes. In the meantime, we shall prepare, for the brave sky-travellers, maps of the celestial bodies.

from a letter by Johannes Kepler to Galileo Galileo written in 1610, cited here

Image from Francis Godwin (1638)

Earthshine

Leonardo sketched it.

Galileo explained it as he sought to show the earth was not excluded from "the dance of stars." 

Recent research shows that the brightness of the earthshine varies as the Earth rotates because of the greater reflection from the mirror-like oceans compared to the continents. 

Earthshine is most often experienced in still and gentle conditions.

Photo Kevin Bourque via APOD