The Most Famous
Asteroids

What makes an asteroid famous?

Asteroid fame comes from three different directions. The first asteroids ever discovered, Ceres and Vesta, are famous by virtue of history. Apophis and Bennu became widely known because of their impact risk calculations. Eros and Itokawa earned recognition through spacecraft missions that revealed what these bodies actually look like up close. Most famous does not mean most dangerous: Ceres and Vesta are enormous, but both orbit in the main belt, far from Earth.

Eight famous asteroids at a glance

The first asteroids discovered

Giuseppe Piazzi spotted Ceres on New Year's Day 1801 from Palermo, Sicily. He initially thought he had found a small planet. Within a few years, astronomers discovered Pallas (1802), Juno (1804), and Vesta (1807), leading to the understanding that a whole population of small bodies occupied the region between Mars and Jupiter. These early discoveries were made with modest telescopes and painstaking observation.

Vesta is the only main-belt asteroid bright enough to be occasionally visible to the naked eye under perfect dark-sky conditions. Its surface is heavily cratered, and a massive impact event near its south pole ejected the material that eventually became the HED group of meteorites found on Earth. When the Dawn spacecraft orbited Vesta in 2011 and 2012, it confirmed this link by matching the surface mineralogy to laboratory samples.

Near-Earth asteroids that changed planetary defence

Eros was discovered in 1898, making it the first known near-Earth asteroid. At the time, the concept of planetary defence did not exist. By the time NEAR Shoemaker landed on Eros in February 2001, it had become clear that monitoring and cataloguing these objects was essential.

Apophis changed everything in 2004. Initial calculations suggested a 1 in 37 chance of impact in 2029, the highest probability ever recorded for a sizeable asteroid. The figure dominated news coverage for weeks. Subsequent observations refined the orbit and eliminated the 2029 risk, but the event demonstrated how quickly an apparently dangerous discovery could be resolved with more data.

Bennu remains the most closely monitored asteroid on the Sentry table. Samples returned by OSIRIS-REx in 2023 are helping scientists better understand the Yarkovsky effect, a tiny thermal force that slowly shifts asteroid orbits. Measuring this effect accurately is the key to predicting whether Bennu will pass through a gravitational keyhole in 2135 that could set up a later impact.

The missions that revealed what asteroids actually are

Before spacecraft visited asteroids, they were little more than points of light. NEAR Shoemaker's orbital survey of Eros revealed a battered, elongated body covered in regolith and craters. The surprise was how uniform and rocky it appeared: a single coherent body, not a loosely bound collection of debris.

Itokawa told the opposite story. Hayabusa 1's images showed a peanut-shaped body with almost no craters, covered in boulders, and almost certainly a rubble pile, two separate bodies held together by gravity rather than structural strength. This distinction matters enormously for planetary defence: a solid asteroid and a rubble pile respond very differently to any deflection attempt.

Florence's 2017 flyby at roughly 7 million kilometres was the closest known pass by a kilometre-scale asteroid in recorded history. It was tracked by radar from Goldstone and Arecibo, and astronomers discovered it has not one but two small moons, an unexpected finding that revealed its internal density.