Decades: 330s BC 320s BC 310s BC 300s BC 290s BC - **280s BC** - 270s BC 260s BC 250s BC 240s BC 230s BC

285 BC 284 BC 283 BC 282 BC 281 BC **280 BC** 279 BC 278 BC 277 BC 276 BC 275 BC

- Battle of Heraclea: The Greeks, led by Pyrrhus of Epirus, defeat with severe casualties a Roman army the first time these cultures meet in battle.
- Aristarchus uses the size of the Earth's shadow on the Moon to estimate that the Moon's radius is one-third that of the Earth.
- Achaean League refounded.

- Philon of Byzantium