5th century BC: Greek explorer Pytheas of Massalia travels to the British Isles and possibly as far as Iceland and Norway.
1st century BC: Roman general and explorer Julius Caesar invades Britain and records his observations of the British Isles.
10th century AD: Norse explorer Leif Erikson reaches North America, becoming the first European to set foot on the continent.
13th century: Venetian explorer Marco Polo travels through Asia, visiting China, India, and other regions. His book, The Travels of Marco Polo, becomes one of the most influential travelogues in history.
15th century: Portuguese explorer Henry the Navigator initiates the Age of Exploration, sponsoring expeditions to Africa and the Americas.
1492: Italian explorer Christopher Columbus, funded by the Spanish crown, reaches the Americas, believing he had reached Asia.
16th century: Spanish explorers Hernán Cortés and Francisco Pizarro conquer the Aztec and Inca empires in the Americas.
17th century: Dutch explorer Abel Tasman explores the coast of Australia and discovers New Zealand.
18th century: British explorer James Cook sails the Pacific Ocean, charting the coast of Australia and discovering the Hawaiian Islands.
19th century: European powers engage in a period of intense exploration, colonizing Africa, Asia, and Oceania.
20th century: The era of space exploration begins with the launch of the first artificial satellite, Sputnik, in 1957.
Present day: Ongoing scientific and commercial exploration of space continues, with missions to the Moon, Mars, and beyond.