Space Exploration Costs the Same as Exploring the World

The Solar System is much vaster than the Earth, but the speeds of our spacecraft are, of course, much greater than the speeds of the sailing ships of the fifteenth and sixteenth centuries. The spacecraft trip from the Earth to the Moon is faster than was the galleon trip from Spain to the Canary Islands. The voyage from Earth to Mars will take as long as did the sailing time from England to North America; the journey from Earth to the moons of Jupiter will require about the same time as did t...

 Invasive Species Between the Old and New World

Many plants new to North America first sprouted up alongside wharves and shipyards. From there they made their way inland along new roads hacked out of the wilderness, and later along canals and railroad embankments, taking up residence in any sort of disturbed soil. Native plants adapted to quiet precolonial forests and meadows gave little competition to the aggressive intruders. As Pilgrims and Puritans leveled the ancient New England forests, their floral co-colonists thrived in a landscap...