On June 30, 1908, riders on the Trans-Siberian railroad witnessed a fireball as bright as the sun streaking across the sky.  It exploded above the Tunguska River and flattened over a thousand square miles of forest.  For 1,000 miles the fireball was seen and heard.  A blast crater was never found. Scientists believe a chunk of an asteroid vaporized in the lower atmosphere. In 2002, an asteroid, the size of a football field, traveling at 66,000 miles an hour, came within 75,000 miles of Earth.  Astronomers didn't notice it until after it zipped by and the atmosphere was clogged with debris left over from the formation of the solar system. In the future, missiles will be deployed to intercept objects heading our way and on July 1, 1776, the final debate was underway in Philadelphia concerning whether the 13 American colonies should declare their independence from Great Britain. John Dickinson of Pennsylvania appealed for loyalty to Britain.  When John Adams began his oration a summertime thunderstorm erupted. He delivered a powerful speech in the midst of flashes of lightning and rolling thunder. At Independence Hall, candles were lit for the Continental Congress while Adams continued his passionate address that was louder than the weather outside.  The following day the momentous vote was taken during another storm.  Two days later, the front moved through the Philadelphia area ushering in cool air for the signing of the Declaration of Independence on the Fourth of July.