THE SOLAR SYSTEM
Arizona mainly to study Mars, and equipped it with
an excellent 61-centimetre (24-inch) refractor. Lowell
believed that the canals represented a planet-wide irriga-
tion system, built by the local inhabitants to pump water
from the ice-caps at the poles through to the equator.
Disappointingly, it has now been proved that the canals do
not exist; they were merely tricks of the eye, and Lowell’sPLANETARY DATA – MARSSidereal period 686.980 days
Rotation period 24h 37m 22s.6
Mean orbital velocity 24.1 km/s (15 miles/s)
Orbital inclination 1° 50’ 59”.4
Orbital eccentricity 0.093
Apparent diameter max. 25”.7, min. 3”.5
Reciprocal mass, Sun = 1 3,098,700
Density, water = 1 3.94
Mass, Earth = 1 0.107
Volume, Earth = 1 0.150
Escape velocity 5.03 km/s (3.1 miles/s)
Surface gravity, Earth = 1 0.380
Mean surface temperature 23°C
Oblateness 0.009
Albedo 0.16
Maximum magnitude 2.8
Diameter (equatorial) 6794 km (4222 miles)Schiaparelli’s charts
of Mars, compiled from
observations made between
1877 and 1888. The main
dark features are clearly
shown – but so too are
the canals, which are now
known to be non-existent!
Schiaparelli’s map uses
the nomenclature which
he introduced in 1877, and
which is still followed today.Martians have been banished to the realm of science fiction.
The best pre-Space Age maps of Mars were those
drawn up by E. M. Antoniadi in the 1920s and early
1930s. The telescope used was the Meudon 83-centimetre
(33-inch) refractor, and Antoniadi’s charts proved to be
amazingly accurate, but the real ‘breakthrough’ came with
Mariner 4 in 1965.The Lowell 61-cm
(24-inch) refractor at
Flagstaff, used by Percival
Lowell to draw the Martian
‘canals’.Earth▼ Sketch of Mars that
I made on 23 February 1981,
using a magnification of
815 on the Lowell
telescope. The main features
are clearly shown – but no
canals!C Atl of Univ Phil'03stp 2/4/03 3:04 pm Page 77