We were just recovering from pandemic diseases and into new year 2021 when some asteroids saw approaching Earth. NASA (National Aeronautics and Space Administration) had earlier alerted the world about 6 asteroids, including two whose sizes were approximately equal to the Eiffel Tower in Paris. The news was broadcasted about 6 asteroids which would be encountering Earth on January 6.
2021 AC was the name given to the first one, which nearly made its way past without touching Earth on January 6. The size of it was comparatively very smaller than that of 2008 AF4 and to about 37 metres [or meter(s)] radial size. The second one was 2016 CO247, whose size was approximately 170 metres in radius, went past Earth just after last-mentioned. Both were at a speed more than 30,000 mph and away from Earth at a distance of 7.821806172e-7 light-year.
2021 AJ was the smaller one among 6 which had less than 10-metre radial size. It went past Earth on the same day and two hours later from the time 2016 CO247 moved. 2018 KP1 with 16-metre radial size followed by AJ was 3.276702585e-7 light-year away from Earth and gradually had a decelerating speed due to friction in the space. 2021 AU with 30-metre size was also behind of KPI. All 3 were at different speeds less than 9000 mph.
The last, and giant, 2008 AF4 one was the largest with an approximate radial size of 250-metre went past in the night. Its impact would have equivalent to the nuclear bombs, and to some extent that would have been the largest blow ever. The speed of it was noticed around 20,000 mph and was at a distance of 1.585501251e-6 light-year. Eventually, it was not a threat as per reports.
NASA, on the other hand, had already indicated that the 6-asteroid substance does not cause any threat. NEO (Near-Earth Object) is the one that enters our atmosphere as it usually burns upon due to atmospheric friction against the gravitational speed and hit the ground in pieces only or depending upon its size.