Mars Gallery

Epicycles of Mercury and Venus, 1823

Epicycles of Mercury and Venus, 19th-century diagram. This geocentric (Earth-centred) model shows the orbits of Mercury and Venus as a series of epicycles (loops). Mercury and the Sun are at lower left. Venus is at upper right. The heliocentric system of Copernicus and Kepler replaced these epicycles with elliptical orbits around the Sun. At lower left is an astronomical quadrant. At lower right are the proportional magnitudes of 12 solar system bodies (see C017/8059) and of the Sun as seen from those bodies. The Georgium Sidus is Uranus. This page is from Universal Technological Dictionary (1823) by British author George Crabb (1778-1851)

© MIDDLE TEMPLE LIBRARY/SCIENCE PHOTO LIBRARY

Artwork of the early Earth-Moon system

Artwork of the young Earth-Moon system. The Earth had recently formed when it was struck by a protoplanet ?" called Theia ?" roughly three times the size of Mars. Debris from the impact went into orbit, while the cores of the two planets merged. Within weeks of the event, the debris formed a Saturn-like ring around the Earth. Later collisions in this ring led to the formation of the Moon, probably within just a few thousand years. Initially the Earth and Moon were much closer together than they are now, and spinning more quickly

© MARK GARLICK/SCIENCE PHOTO LIBRARY

Mars and its Two Moons

An artwork of the terrestrial planet Mars set against the backdrop of the Milky Way. Mars's two moons, Phobos and Deimos, are seen passing in front. In this view of Mars we can see Valles Marineris in the middle - a vast chasm compared to which the US's Grand Canyon is little but a scratch. While off to the left we can see the Tharsis rise with its four giant volcanoes, the largest of which (Olympus Mons) is the most massive volcano in the known Solar System

© MARK GARLICK/SCIENCE PHOTO LIBRARY