1954

Association of Lunar and Planetary Observers (A.L.P.O.)

1954

Source

1960

Both, Ernst E., A.L.P.O. Map of Mars for 1960-1961

These maps are updated regularly.

See http://www.alpo-astronomy.org/jbeish/Observing_Mars_4.html

Alpo Map of Mars

This large up-to-date map of the surface of the planet Mars has been compiled by D. P. Avigliano, Sierra Madre, Calif., from observations made during the favorable 1954 opposition by members of the Association of Lunar and Planetary Observers. It shows only those markings recorded independently by two or more observers.

As in other Mars charts, north is at the bottom, and east to the left, matching the orientation in a telescope. The names of the markings are, for the most part, those used by Percival Lowell and E. M. Antoniadi. Additional names for recently detected details have been assigned by S. Ebisawa, T. R. Cave, Jr., and by Mr. Avigliano.

The following abbreviations have been used: D, Depressio (depression); F, Fons (spring); FR, Fretum (strait); IN, Insula (island); L, Lacus (lake); M, Mare (sea); P, Palus (swamp); PO, Portus (harbor); PR, Promontorium (cape); R, Regio (region); S, Sinus (gulf). Conventionally, the terms suggesting water are used for dark Martian markings, and those applicable to land for the bright reddish areas.

Unlike the stable lands and seas of Earth, the green areas of Mars change perceptibly and sometimes strikingly from one opposition to the next, spreading or shrinking, and darkening or fading. As a result, the Martian surface can never be mapped once and for all, and is of much interest to compare this 1954 representation with earlier ones of the Martian surface.

Two Antoniadi maps of Mars have been reproduced in Sky and Telescope. On page 413 last month is one from his own observations of 1909 to 1937, and page 268–9 of the June, 1954, issue contain a 1914 chart, based on observations by members of the British Astronomical Association. The former is much more crowded with detail, summarizing as it does three decades of work with a 33-inch telescope.

In comparing the maps, the reader should make allowance for the different modes of representation used by the two map makers, and for the exaggerated contrast needed to depict subtle shadings.

Any chart of Mars is necessarily a compilation from many sketches or photographs, each showing only a small sampling of the elusive detail. In piecing together these fragmentary views, the cartographer often has much difficulty in identifying isolated markings or canals. Even the best of Martian maps show some inconsistencies in identification. Thus the name Isedon (near longitude 80°, latitude 40° north) is not applied by Mr. Avigliano to the same feature as in the 1909–1937 map.

Erroneous positions can occur, if markings are inserted by estimation in a Mars map from a drawing. Careful measurements are desirable for their areographic longitudes and latitudes. The older maps of Schiaparelli, Jarry-Desloges, and Trumpler are noteworthy for the pains taken to secure accurate placement. But even if the cartographer is careful, the drawings from which he works may have their distortions. A particularly troublesome part of Mars is the Arcadia-Amazonis region at the lower right part of the 1954 map. Here the markings are mostly dim and vague, with few well-defined reference points, and so disagreement there is not too surprising.

J. A.