NASA expects the asteroids to individually approach our planet on Saturday, September 21. The space rocks are estimated to measure between 59ft (18m) at their smallest and 275.6ft (84m) at their largest. All three have been named NEOs or Near-Earth Objects – rocky objects that come close to our planet at high speeds. The first of the asteroids, dubbed by NASA Asteroid 2017 SL16, will zip by in the wee morning hours.
NASA predicts the asteroid will approach Earth around 3.13am BST (2.12am UTC) this weekend.
The asteroid only measures between 59ft and 134ft (18m and 41m) in diameter but it is headed on a Close Approach trajectory.
As it barrels through space, the rock will skim the planet at breakneck speeds of 6.47km per second or 14,472mph (23,292kph).
The good news, however, is the asteroid will give our planet a wide berth.
At its closest, Asteroid SL16 will approach our planet from a distance of 0.02027 astronomical units or au.
A single astronomical unit describes the distance from our planet to the Sun or about 93 million miles (149.6 million km).
This means NASA expects the asteroid to miss Earth by a distance of 1.8 million miles (3.03 million km).
It is very difficult to imagine the distances involved
European Space Agency (ESA)
On the grand scale of the universe, seemingly long distances like these are tiny.
The European Space Agency (ESA) said: “Space is huge. It is so immense that it is very difficult to imagine the distances involved, even between the objects in our local neighbourhood, the solar system.”
NASA also said: “As they orbit the Sun, Near-Earth Objects can occasionally approach close to Earth.
“Note that a ‘close’ passage astronomically can be very far away in human terms: millions or even tens of millions of kilometres.”
The second space rock, Asteroid 2017 SM21, is trickier because NASA’s Centre for Near Earth Object Studies has calculated two approaches on Saturday.
Asteroid SM21 is estimated to be smaller than its predecessor and will approach Earth around 5.52am BST (4.52am UTC).
The rock measures somewhere in the range of 49ft to 108.3ft (15m to 33m) across.
The asteroid is flying through space at speeds of around 9.61km per second or 21,497mph (34,596kph).
WATCH HERE: Major asteroid DESTROYS Earth in fiery crash simulation
NASA’s minimum approach trajectory on Sunday will bring the asteroid within 0.00818au or 760,378 miles (1.2 million km) of Earth.
On this dangerously close approach, the rock would swing by from a distance three times as far as the Moon is.
But a second trajectory calculated by NASA shows a much more comfortable nominal distance of 0.02939au.
In this scenario, the asteroid will miss our home planet from a distance of 2.7million miles (4.39 million km).
The third of the bunch, Asteroid 2019 RBS3, is the largest, fastest but also the farthest of the three asteroids.
NASA’s observations show the rock’s diameter sits somewhere in the range of 124.6ft 275.6ft (38m to 84m).
The rock is currently flying towards Earth at speeds of around 11.83km per second or 26,4362 (42,488kph).
But the good news is the asteroid is also expected to safely shoot past the Earth this weekend without striking.
At its closest, the asteroid will close-in on Earth from a distance of 0.04864au or 4.5 million miles (7.27 million km).
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