Original: Observations with the infrared Spitzer Space Telescope show a diameter of 10370 to be 70 km (43 miles) plus or minus 20 km (50 to 90 km in diameter), or a 35 km radius.
Simplified: Sightings with the Spitzer Space Telescope show that it's diameter is about 70 km (43 miles) plus or minus 20 km (50 to 90 km in diameter), or a 35 km radius.