Researchers from Stanford University say an asteroid that hit the Earth 3.26 billion years ago dwarfed the one that killed the dinosaurs. Causing the oceans to boil and the Earth to shake for half an hour, the rock hit the planet at approximately 44,000 miles per hour and was at least 23 miles in diameter. The impact center was greater than the distance between New York and Washington D.C. -- about 300 miles in diameter. The asteroid that ended the dinosaurs was about 6 miles in diameter and had an impact center 93 miles in diameter. "We knew it was big, but we didn't know how big," Donald Lowe, a geologist at Stanford University and a co-author of the study, said of the asteroid. The impact occurred during what scientists call the Late Heavy Bombardment and caused seismic waves similar to a 10.8-magnitude earthquake. Due to the erosion and movements of the Earth's crust, the craters left by the asteroids are gone. Scientists want to continue to learn about the asteroid impacts through studies of ancient rock formations. The research is to be published in the journal Geochemistry, Geophysics, Geosystems.