LA SERENA, Chile: Tens of thousands of tourists and locals gaped skyward Tuesday as a total eclipse of the sun darkened the heavens over Chile and Argentina. Tourists from around the world gathered to witness the cosmic spectacle, which began in the morning as the moon crossed in front of the sun and cast a shadow that passed over a tiny uninhabited atoll in the South Pacific and headed to South America. Chile and Argentina were the only inhabited places where the total eclipse could be seen.