Classical albedo features on Mars

Early telescopic astronomers, observing Mars from a great distance through primitive instruments (though they were advanced for their day), were limited to studying albedo contrasts on the surface of the planet.

When Giovanni Schiaparelli began observing Mars in 1877, he believed that the darker features were seas, lakes, and swamps and named them accordingly in Latin (mare, lacus, palus etc.).

Over the next two decades the most prominent features picked up various informal names (such as the Hourglass Sea for what is now Syrtis Major Planum) but there was no overall system.

Proctor's names remained in use for several decades, notably in several early maps drawn by Camille Flammarion in 1876 and Nathaniel Green in 1877.

In 1958, the International Astronomical Union set up an ad hoc committee under Audouin Dollfus, which settled on a list of 128 officially recognised albedo features.

This involved a considerable amount of pruning; Antoniadi's La Planète Mars had mentioned 558 named features.

Richard A. Proctor's map of Mars, which named albedo features after astronomers. North is at the bottom, as seen through an inverting telescope.
Nathaniel Green's 1877 Mars map, which used many of Proctor's names. North is at the bottom.
Early Schiaparelli map, from an 1888 encyclopedia.
Early map by Flammarion and Antoniadi . North is at the bottom.
Mars albedo features after the 1958 official list of names, but before the 1972 observations of Mariner 9 .
Classical albedo features on Mars, whose names date back to Schiaparelli (1888 map above), share some boundaries with more recent satellite observations. [ 4 ]