Paleo-Indians migrated from Siberia to the North American mainland at least 12,000 years ago. European colonization began in the 16th century. The United States emerged from the thirteen British colonies established along the East Coast. Numerous disputes between Great Britain and the colonies led to the American Revolutionary War lasting between 1775 and 1783, leading to independence. The United States embarked on a vigorous expansion across North America throughout the 19th century—gradually acquiring new territories, displacing Native Americans, and admitting new states—until by 1848 it spanned the continent.
During the second half of the 19th century, the American Civil War led to the abolition of slavery in the United States. The Spanish–American War and World War I confirmed the country’s status as a global military power.
An Icy Nest Of Space Eggs. Methone is actually only one member of an icy nest of Space eggs, which also includes the very strange and smooth moons of Saturn, Pallene and Aegaeon. Aegaeon is a very, very small moonlet that also twirls around between Mimas and Enceladus. Like Methone, Aegaeon displays a mysteriously unblemished surface.
The team of scientists used data gathered by NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission, composed of a duo of twin spacecraft that circled Earth's Moon throughout 2012, each measuring the push and pull of the other as an indicator of lunar gravity.
Only recently have space missions begun to solve this beguiling Solar System mystery--that a small number of distant moons have been successfully hiding, from the curious eyes of astronomers, life-sustaining liquid water beneath secretive shells of ice.