An asteroid as big as a house flew past Earth this morning, narrowly avoiding the ring of communications satellites orbiting 22,236 miles above the planet's surface.
The 2012 TC4 asteroid is estimated to be 45 to 100 feet (15 to 30 meters) in size and made its nearest approach to Earth over Antarctica at 06:42 BST this morning, passing by at a distance of around 26,000 miles - a little over one-tenth the distance to the Moon, reports the Mirror .
The 2012 TC4 asteroid had initially been spotted by the Pan-STARRS observatory in Hawaii back in 2012, but its orbit meant that it was unable to tracked.
Based on these observations, however, astronomers predicted that it should come back into view in the autumn of 2017.
Observers with the European Space Agency and the European Southern Observatory were the first to recapture 2012 TC4 in late July 2017, using one of their large 8-metre aperture telescopes.
Since then, observers around the world have been tracking the object as it approaches Earth and reporting their observations to the Minor Planet Center.
Scientists used the close flyby of 2012 TC4 as an opportunity to test the "worldwide asteroid detection and tracking network" - a volunteer project conceived and organised by NASA-funded asteroid observers, and supported by the NASA Planetary Defense Coordination Office (PDCO).
The aim of the project is to encourage astronomers - both professional and amateur - to work together to identify potential real asteroid-impact threats.
No asteroid currently known is predicted to impact Earth for the next 100 years. However, if an asteroid the size of 2012 TC4 was to enter our atmosphere, it would have a similar effect to the Chelyabinsk meteor, which exploded in an air burst over Chelyabinsk Oblast, Russia, in February 2013.
The meteor generated a bright flash and produced a hot cloud of dust and gas. The bulk of the object's energy was absorbed by the atmosphere, but some eyewitnesses felt intense heat from the fireball.
While the main purpose of NASA's PDCO is to track potentially hazardous asteroids and comets, the US space agency is also putting in place measures to deflect any space rocks that are found to be on a collision course with Earth.
It is developing a special type of spacecraft called DART (Double Asteroid Redirection Test), which is about the size of a fridge, and can be fired at an asteroid with enough force to change its trajectory .
NASA plans to test out DART on a pair of asteroids named Didymos A and B, which are scheduled to make a "distant approach" to Earth in October 2022.
While small asteroids hit the Earth every day, larger ones like the Didymos twins could cause real problems if they hit us. And this is why NASA wants to use them as target practice.
Using an on-board targeting system, DART will fly itself to Didymos B and smash into it at 3.7 miles-per-second , in an impact that will be visible from Earth-based observatories.
The impact will theoretically change the speed and direction of the asteroid by just enough to shift it out of Earth's path.