History of asteroid discovery: Ceres (1801) through expanding near-Earth object census. Ceres was the first asteroid discovered on New Year's Day 1801 by Giuseppe Piazzi at the Palermo Observatory, measuring 583 miles in diameter Pallas was the second asteroid discovered in 1802 by Heinrich Olbers, third largest at 318 miles average diameter Juno was discovered September 1, 1804 by Karl Ludwig Harding, second largest at 157 miles mean diameter
Ceres kicked off asteroid science in 1801 when Giuseppe Piazzi spotted it at Palermo Observatory — a 583-mile-wide giant. Vesta, Juno, and Pallas followed by 1807. The game-changer: 1898's Eros, first near-Earth asteroid found, and 1932's Apollo, first confirmed Earth-orbit crosser.
Key Facts
- Ceres was the first asteroid discovered on New Year's Day 1801 by Giuseppe Piazzi at the Palermo Observatory, measuring 583 miles in diameter
- Pallas was the second asteroid discovered in 1802 by Heinrich Olbers, third largest at 318 miles average diameter
- Juno was discovered September 1, 1804 by Karl Ludwig Harding, second largest at 157 miles mean diameter
- Vesta was discovered March 29, 1807 by Heinrich Wilhelm Olbers, second most massive at 326 miles mean diameter
- 1898 marked discovery of the first asteroid (Eros) seen approaching Earth
- 1932 Apollo asteroid became first to cross Earth's orbit
- By 1990 about 135 near-Earth objects (NEOs) were known; estimated number larger than 1 km in diameter is about 25,000
Source: THE ASTROID EPISODE: The Dangers and Opportunities by The Randall Carlson