Complex sentence: It measures about 100 kilometers in diameter (130 km along its major axis) and is the largest asteroid to have been visited by a spacecraft by 2010, the "Rosetta" probe passed within 3,162 km (1,964 miles) in July 2010.
Split into simpler sentences: It measures about 100 kilometers in diameter (130 km along its major axis). Lutetia is to date the largest asteroid to have been visited by a spacecraft; the "Rosetta" probe passed within 3,162 km (1,964 miles) in July 2010.