However, other features revealed by these observations are of importance and the appearance as shown in the Viking photographs from a height of about 1000km shows that it still resembles a face to an incoming space traveller, probably to indicate an inhabited planet. The diagram also confirms that M is an artifact, as it is part of the scale model of the Sun and planets. On the surface of Mars the distance MS is 36.1km. The mean radius of Mars is 3390km. M. It is not possible to be more precise, but it does support the scale of 1,000pi when combined with other measurements.
E represents the planet Earth.
The object E shows more erosion than M, suggesting it was formed from softer material, as noted later. The distance SE on the surface of Mars is 24.1km. The mean radius of Earth is 6371km. A circle of this radius fits the M 'face' reasonably well and shows that the size of E in relation to M is similar to the relative size of Earth and Mars. V represents the planet Venus.