• A large asteroid is set to pass by the Earth on Saturday in a once-in-a-decade event.
• The asteroid will pass between Earth and the moon's orbit, bringing it relatively close.
• It may be visible to some in the Northern hemisphere and could look like a "slow-moving star."

A large asteroid is set to zoom past the Earth on Saturday at an unusually close distance, putting it closer to the planet than the moon.

The newly discovered space rock, named 2023 DZ2, is expected to safely fly by on Saturday, according to NASA. The asteroid is expected to travel at speeds faster than 17,400 miles per hour and have a diameter between 140 feet to 310 feet, or around the size of a small skyscraper. 

"While close approaches are a regular occurrence, one by an asteroid of this size (140-310 ft) happens only about once per decade, providing a unique opportunity for science," NASA said.

The asteroid is expected to pass by around 108,000 miles away from the Earth, which is a little closer than half way between the planet and the moon.

—NASA Asteroid Watch (@AsteroidWatch) March 21, 2023

NASA said astronomers with the International Asteroid Warning Network, a group of organizations that tracks and plans for the risk of an asteroid impact, are studying DZ2 to help with planetary defense if an asteroid threat was ever discovered.

The asteroid will be closest to Earth at around 3:50 p.m. Eastern time on Saturday, according to EarthSky. The asteroid may be visible through small telescopes. The best chance of seeing it is on Friday night from the Northern Hemisphere. EarthSky said its close proximity to Earth may make it appear like a "slow-moving star."

The asteroid is also passing by days before five planets — Mercury, Jupiter, Venus, Uranus, and Mars  — are expected to align with the moon and form a great arc across the night sky in a rare cosmic event.