Massive Asteroid & Its Tiny Moon Caught On Camera During Close Flyby Of Earth

ESO

In late May, a massive, nearly mile-wide asteroid paid Earth a close visit, safely passing within 3.2 million miles of our planet’s surface. Dubbed asteroid 1999 KW4, the formidable space rock measured about 0.8 miles in diameter and was accompanied by its very own moon, as reported by The Inquisitr last month.

The asteroid pair zoomed past Earth on May 25, hurtling through space at breakneck speeds of 48,000 mph. While their close flyby of our planet certainly made headlines at the time, particularly since it was announced that the asteroid would be visible from Earth, there were more than space enthusiasts looking up at the sky that night. An entire host of astronomers assembled to observe the passing space rocks during their close approach to Earth and even managed to catch them on camera, Space is reporting.

Despite buzzing our planet from a few million miles away, asteroid 1999 KW4 and its smaller companion were photographed by the European Southern Observatory’s (ESO) Very Large Telescope (VLT). Equipped with a state-of-the-art imagining instrument designed to find exoplanets in the deep cosmos, the VLT pointed its camera – SPHERE, or the Spectro-Polarimetric High-contrast Exoplanet REsearch instrument – at asteroid 1999 KW4 and snapped the “sharpest” image ever obtained of the now-famous space rock.

Unveiled by ESO on June 3, the photo was showcased next to an artist’s impression of asteroid 1999 KW4 and offered a clear glimpse of the massive space rock and its satellite, found in orbit around the majestic asteroid.

“The left-hand image shows SPHERE observations of asteroid 1999 KW4,” ESO officials explained in the photo release.

“The angular resolution in this image is equivalent to picking out a single building in New York — from Paris.”

The imposing space rock and its tiny moon are known as a binary – or double – asteroid. First spotted in 1999, the pair circles the sun every 188 days, passing between the orbits of Venus and Earth. This makes asteroid 1999 KW4 a frequent visitor of our corner of space.

According to ESO, its latest flyby of planet Earth was monitored in an extensive observing campaign put together by the International Asteroid Warning Network (IAWN). This offered ESO’s VLT the perfect chance to take a good look at the massive asteroid as it darted past Earth at 13.5 times the distance to the moon.

“This distance is about 14 times the distance to the Moon — close enough to study, but not close enough to be threatening!”

As ESO pointed out, SPHERE is “one of the very few instruments in the world capable of obtaining images sharp enough to distinguish the two components of the asteroid” – both the 0.8-mile main body and the small moon, which orbits the space rock at a distance of about 1.7 miles.

Artist’s impression of the double asteroid 1999 KW4 during its Earth fly-by.
Artist’s impression of the double asteroid 1999 KW4 during its Earth fly-by.Featured image credit: ESO/M. Kornmesser

While asteroid 1999 KW4 doesn’t pose any threat to our planet and harmlessly whizzes past Earth on its journey around the sun, its latest flyby created a good opportunity for scientists to engage in an observing exercise that could help prepare for a hypothetical collision scenario.

“These data, combined with all those that are obtained on other telescopes through the IAWN campaign, will be essential for evaluating effective deflection strategies in the event that an asteroid was found to be on a collision course with Earth,” said ESO astronomer Olivier Hainaut.

“In the worst possible case, this knowledge is also essential to predict how an asteroid could interact with the atmosphere and Earth’s surface, allowing us to mitigate damage in the event of a collision.”

The double asteroid bears a striking similarity to another binary system called Didymos. Just like 1999 KW4, the 0.48-mile Didymos is also accompanied by its own moon – a 525-foot space rock dubbed “Didymoon.” However, unlike our recent celestial visitor, Didymos “could pose a threat to Earth sometime in the distant future,” notes ESO.

As such, the space rock and its satellite will serve as the target of NASA’s DART mission, a pioneering planetary defense experiment designed to fly a spacecraft into Didymoon and impact the object to change its orbit around its larger twin. This will, in turn, help scientists determine how much such an impact can change the orbit of an asteroid and possibly deflect it.