Were the orbits of the two planets in the same plane, a transit would occur at every inferior conjunction, but this is not the case. The orbit of Venus is inclined at an angle of 3.4 degrees, and transits are rare. At the present epoch they are seen in pairs, the components of a pair separated by eight years - after which no more transits are seen for over a century.

Thus, there were transits in 1631,1639 1761,1769 1874 and 1882. The next will be June 8, 2004.

In 1882 during one such transit of Venus Elizabeth Parker persuades her nephew to move to America after she has a vision of an area, which can only be the American West.

Six years later two lone cowboys lean over the frost-covered manes of their exhausted horses as they make their way against a freezing wind one December day in 1888. The cattlemen, Richard Wetherill and Charlie Mason had started out at sunrise searching for strays that would surely perish if left to wander the canyons and mesas above the Mancos River. Already the sun is low and the temperature is dropping fast as night approaches. The cowboys eventually break out of the under brush along the rim rock high above the river where they stop momentarily to get their bearings and to rest their horses.

All around them is the great escarpment that dominates the southern horizon of the Montezuma Valley between the towns of Cortez and Mancos. So rugged is this vast landscape that the explorers and pioneers used to pass through the quiet valley below rather than confront the defiant north edge of the river canyon's massive walls.

Wetherhill and Mason peer through the shifting snow that whirls in the wind, trying to catch sight of their lost cattle. As they scan the broken canyon walls and the valley below, the air suddenly clears: a rush of frigid air sweeps the snow away and in the brilliant clear atmosphere they momentarily see what looks like a stone house...a whole series of stone houses...floating in midair.

The two cowboys stare incredulously at one another. Without knowing it they are the first white people to discover some of the most remarkable archaeological ruins north of Mexico.

For here standing silent, and protected by a gigantic recess in the face of the cliff across from them, is an awesome sight. Under the roof of a huge cave that ages of seeping water has eroded in the cliff face are some of the best-preserved cliff dwellings in North America, ruins that lay totally undisturbed for centuries after the last survivor of the mysterious people who built them vanished.