Bus-Size Asteroid Makes Closest Approach Of The Entire Year, Gets Spotted Only A Day After

On August 10, Earth had its closest encounter with an asteroid since the beginning of the year, when a space rock roughly the size of a bus came darting past us closer than the moon.

But the 15-meter (49-foot) asteroid wasn't picked up by our telescopes until the very next day, CNET reported earlier this week. Detected by telescopes on Hawaii's Mauna Loa, the asteroid has been dubbed 2018 PD20 and belongs to a group of near-Earth asteroids known as the Apollo asteroids, notes the Daily Star.

During its momentous close visit to our planet last Friday, the space rock came shooting past our planet at a distance of 20,636 miles (33,210 kilometers). That's closer than the orbit of many of our communications satellites, detail the sources, and represents exactly 0.09 LD (lunar distance) and 0.00022 AU (astronomical unit) — where 1 AU is defined as the average distance between Earth and the sun, namely 93 million miles (150 million kilometers).

According to the Small-Body Database Browser of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, asteroid 2018 PD20 is currently at a distance of 0.034 AU from Earth and 1.047 AU from the sun. The space rock is now on its way out of the solar system.

As amateur astronomer Tony Dunn pointed out, it's no wonder that NASA missed the asteroid before its close flyby on Friday. The space rock was coming from the direction of the sun, which made it "undiscoverable prior to closest approach," he tweeted on Monday.

Dunn, who is a high school physics teacher, even made an orbit simulation for the asteroid's close encounter with Earth, revealing that "2018 PD20's trajectory was heavily bent by Earth's gravity."
The GIF posted by Dunn showcases the geosynchronous orbit around Earth (the purple circle), where many of our large satellites are currently floating in space. His simulation shows 2018 PD20 passing inside this orbit and then continuing its journey to exit the solar system, explains CNET.

At the same time, JPL's Ron Baalke — the scientist who broke the news about the meteor explosion over Base Thule at the end of July, the Inquisitr recently reported — took to Twitter to share an illustration of the asteroid as it zoomed past the moon and toward Earth.

Asteroid 2018 PD20 is the 39th space rock to pay us such a close visit and come within 1 LD in 2018. It's also the asteroid with the closest flyby of the year, with 2018 BD coming in second at 0.00026 AU on January 18.

As the Inquisitr previously reported, six other asteroids skimmed by at a close distance from our planet in the last five months, with two coming in at half the lunar distance and one approaching at less than one-third of the distance between Earth and the moon.