A Mile-Wide Asteroid With Its Own Moon to Pass by Earth This Weekend

This handout picture from the European Space Agency (ESA) retrieved on Sept. 3, 2008, shows an artist's rendition of ESA's probe Rosetta's closest approach to Earth during its second swing-by of our planet on Nov. 13, 2007.AFP/Getty Images

An asteroid which measures approximately a mile wide and is orbited by its own moon is expected to pass by the Earth on Saturday, May 25, at speeds of 48,000 mph.

The asteroid, which was discovered 20 years ago, is dubbed by NASA as Asteroid 1999 KW4, and is expected to be visible until May 27.

Despite its “potentially hazardous” classification by the Smithsonian Astrophysical Observatory’s Minor Planet Center, Asteroid 1999 KW4 is expected to pass by Earth safely at 23:05 UTC.

The closest distance the space rock is expected to be from Earth is estimated to be 3,216,271 miles—or 13.5 times the distance to the moon, reported the Mail Online.

The asteroid is described by the Las Cumbres Observatory as “slightly squashed at the poles and with a mountain ridge around the equator, which runs all the way around the asteroid.

“This ridge gives the primary an appearance similar to a walnut or a spinning top.”

“The main body (primary) of 1999 KW4 is about 1300 meters across, but is actually quite a complex shape,” said researchers at Las Cumbres Observatory.

The asteroid, which was first discovered by the Lincoln Near-Earth Asteroid Researcher (LINEAR) astronomical survey in Socorro, New Mexico, in 1999, is estimated to measure somewhere between 0.8 miles to 1.86 miles in diameter, according to NASA’s JPL.

NASA ambassador Eddie Irizarry of the Astronomical Society of the Caribbean confirmed the asteroid will not be visible to the naked eye, but encourages amateur astronomers to try to spot it as it passes Earth.

“1999 KW4 is travelling at 48,123 mph, relative to Earth,” he told EarthSky.

“Its fast speed, combined with the size of this asteroid, will allow amateur astronomers to observe it as it moves in front of the stars.”

“The space rock will not be visible to the naked eye alone but sky enthusiasts equipped with eight-inch in diameter and bigger telescopes might be able to see the asteroid, which might reach a visual magnitude of around 12 during closest approach,” he added.

The European Space Agency (ESA) on May 14 shared an image of the 1999 KW4, “observed from the ground for the first time in the current apparition, emerging from solar conjunction,” it published on its official website.

Collaborating with Observatoire des Makes in the French island La Réunion, the space agency captured the observations as part of the ongoing IAWN observing campaign.

On May 25, it will collaborate with IAWN to “to collect as many observations as possible, with as many observing techniques and wavelengths as possible,” ESA said.

“The goal is to put observatories and telescopes to the test, to become aware of what kind of information can be collected on short notice in case of a future close approach of a possibly threatening asteroid,” the space agency explained.

The asteroid’s next close encounter with Earth will be on May 25, 2036, when it will pass by even closer, according to EarthSky.