Answer:
Roughly 10 km (6 miles) across. (6.2 miles exact)
Step-by-step explanation:
The body that wiped out the dinosaurs was an asteroid roughly 10 km (6 miles) across that hit Earth about 65 million years ago. This impact made a huge explosion and a crater about 180 km (roughly 110 miles) across. The asteroid hit in what is now Mexico's Yucatan peninsula and formed Chicxulub crater, which is over 90 miles across. This massive blast triggered a mass extinction event that ended the reign of the dinosaurs.