‘Planet Killer’ Asteroid To Skim Past Earth This Week; Here’s What To Know About the Mountain-Sized Space Rock

A potentially hazardous asteroid is expected to make a close approach to Earth, passing at only 17 times the distance that the moon is from our planet.

Gigantic, Deadly Asteroid

A huge asteroid is set to whizz past Earth later this week, traveling at around 58,000 miles per hour (93,000 kilometers per hour). The "planet killer" asteroid is one of the largest space rocks to zip close to our planet during the past 125 years.

Officially named 2011 UL21, the asteroid will travel close to Earth on June 27 at about 4.1 million miles (6.6 million kilometers) away. As revealed by the simulations by NASA's Jet Propulsion Laboratory (JPL), its upcoming Earth flyby is closer than it has been to our planet for at least 110 years.

At this distance, the asteroid is classified by NASA as a potentially hazardous object. It is also one of the 10 biggest space rocks to pass within 4.7 million miles (7.5 million kilometers) of our planet since 1900, according to astrophysicist Gianluca Masi from the Virtual Telescope Project (VTP). Fortunately, it does not pose a threat to Earth, either now or in the future.

The asteroid's closest approach can be seen via a free livestream from the VTP, which will share the view from the Bellatrix Astronomical Observatory in Ceccano, Italy. The stream will start at 4 p.m. ET on June 27.

It can also be spotted in the night sky using a decent telescope. Asteroid 2011 UL21 will be at its brightest from the Northern Hemisphere on June 28 and June 29. At its peak brightness, it will have a resemblance to Proxima Centauri, the nearest known star to the Sun.

The mountain-sized space rock will not get this close to our planet again until 2089, when it will get to within 1.7 million miles (2.7 million kilometers) of the Earth. At this point, it will be over two and a half times closer to us than its current approach, according to the simulations from JPL.

So far, there is zero chance that any known planet-killer asteroid will collide with the Earth in the next 1,000 years. However, astronomers expect that there will be smaller asteroids to have some close approach in the next few years. For instance, asteroid Apophis, a space rock big enough to wipe out an entire city, will skim past Earth closer than some satellites in 2029.

Features of 2011 UL21

2011 UL21 is a space rock categorized as a near-Earth asteroid, which means that its orbit occasionally places it within 121 million miles (195 million kilometers) or 1.3 astronomical units (AU) from the Sun. Based on observations, 2011 UL21 may be somewhere between 1.1 to 2.4 miles (1.7 to 3.9 kilometers) wide.

According to the European Space Agency, 2011 UL21 is larger than 99% of known near-Earth asteroids. However, it is about ten times smaller than the Vredefort asteroid, the largest space rock to ever hit our planet. It is also five times smaller than the asteroid which wiped out the dinosaurs 66 million years ago.

Although any potential impact from 2011 UL21 might be less extreme than the historic asteroid collisions, it also has the potential to create damage on a continental scale. It can also release enough debris into the atmosphere to trigger great climatic changes, making it earn its title as a "planet killer."