William Herschel Quote

The spots on Mars are of a different nature. Their constant and determined shape, as well as remarkable color, show them to be permanent, and fastened to the body of the planet.

Astronomical Observations on the Rotation of the Planets Round their, Axes made with a View to determine whether the Earth's Diurnal, Motion is perfectly Equable, Philosophical Transactions of the Royal Society of London, Volume 71