A massive asteroid known as 2011 UL21 is set to make an exceptionally close approach to Earth this week, hurtling past at a speed of approximately 58,000 mph (93,000 km/h).

Despite being classified as “potentially hazardous,” this mountain-sized object will safely pass by our planet, marking one of the largest close encounters with Earth in over a century.

The asteroid orbits the sun every three years, occasionally coming within 1.3 astronomical units (AU) of Earth’s orbit.

Estimated to be between 1.1 and 2.4 miles (1.7 to 3.9 kilometers) wide, 2011 UL21 ranks among the top 1% of known near-Earth asteroids in size, according to the European Space Agency, Live Science has reported.

While significantly smaller than catastrophic asteroids of the past, such as the one that caused the extinction of dinosaurs, its potential to cause continental-scale damage and climatic changes underscores its classification as a “planet killer.”

Despite its proximity, the asteroid will pass about 4.1 million miles (6.6 million km) from Earth on June 27, the closest it has come in over a century, though still significantly farther than the moon.

Written by B.C. Begley