The colossal asteroid, dubbed by NASA Asteroid 2010 PK9, will swing by Earth on Friday, July 26. According to NASA, the asteroid will fly through our corner of space on a so-called “Earth Close Approach” trajectory. NASA expects the space rock to be closest to Earth just after 4pm BST (3pm UTC). When this happens, the space giant will reach breakneck speeds of more than 36,800mph or 16.49km per second.
Asteroid PK9 is an Aten-type NEO or Near-Earth Object first spotted by astronomers nine years ago.
Based on a total of 76 observations, between August 5, 2010, and September 1, 2014, NASA has calculated the space rock’s size, speed and trajectory.
NASA’s observations suggest the imposing asteroid measures somewhere in the range of 393.7ft to 853ft (120m to 260m) in diameter.
At the upper end of that estimate, the space rock dwarfs over the Golden Gate Bridge in San Francisco, US.
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The asteroid is also comparable in height to the Eiffel Tower in Paris, France, and is almost twice as tall as the Great Pyramid of Giza in Egypt.
At the lower end of NASA’s scale, the asteroid is still larger than 14 London double-decker buses in a row.
Thankfully, asteroids this big rarely strike our planet.
NASA said: “Only once every few million years, an object large enough to threaten Earth’s civilisation comes along.
“Impact craters on Earth, the Moon and other planetary bodies are evidence of these occurrences.
“Space rocks smaller than about 25 metres – about 82 feet – will most likely burn up as they enter the Earth’s atmosphere and cause little or no damage.
“If a rocky meteoroid larger than 25 metres but smaller than one kilometre – a little more than half-a-mile – were to hit Earth, it would likely cause local damage to the impact area.”
So, just how close is the imposing asteroid expected to come tomorrow?
According to NASA’s calculations, the asteroid will approach Earth from a distance of about 0.02107 astronomical units (au).
A single astronomical unit describes the distance between the Earth and the Sun – about 93 million miles (149.6 million km).
This means Asteroid PK9 will miss the Earth on Friday from a distance of just 1.96 million miles (3.15 million km).
In other words, the asteroid will fly past Earth about eight times as far as the Moon is.