It's the apocalyptic setting fit for a Hollywood blockbuster – and NASA scientists are about to see it fall.
This week, researchers will hold an exercise at the 2019 Planetary Defense Conference, which will represent a "realistic picture" of an asteroid flying through space on a trajectory impacting Earth.
NASA's Planetary Defense Coordination Office (PDCO) is conducting the simulation exercise as part of a recently announced federal "action plan" to defend our planet against the impact of the asteroid.
The hypothetical asteroid is believed to be about 100 to 300 meters in size and has only a very small probability of reaching Earth on April 29, 2027, according to a NASA page dedicated to the highly detailed scenario.
Global astronomers are always looking for objects near Earth (NEOs), which are classified as asteroids and comets that orbit the Sun and reach 50 million kilometers from Earth's orbit.
Together with the NASA unit, the European Space Agency-NEO Space Situational Awareness Segment and the International Asteroid Alert Network (IAWN) have the task of hunting the skies for potentially dangerous space rocks.
These "table exercises" are not uncommon and try to follow the steps that must be taken with governments and emergency agencies to mitigate the risk to society if the unthinkable happens.
"These exercises really helped the planetary defense community understand what our colleagues on the disaster management side need to know," said Lindley Johnson, NASA's planetary defense officer. "This exercise will help us to develop more effective communications with each other and with our governments."
NASA has been tasked with identifying and tracking 90 percent of meteors close to Earth that are larger than 140 meters by 2020. But the task could end up taking almost three decades, experts say. And yet we are far from being protected.
Last month, it was revealed that a relatively small undetected meteor exploded over the Bering Sea in Russia on 18 December. The explosion – which happened 25.6 kilometers above the surface of the Earth – released 10 times the energy produced by the atomic bomb in Hiroshima in World War II.
Six years ago, a meteor exploded over the Russian city of Chelyabinsk and launched a shock wave that destroyed thousands of windows and injured more than 1,600 people. That meteor was only 19 meters wide.
"The problem is that of Chelyabinsk and the latter (in December) is about 10 times smaller" than the targets of NASA's mandate, astronomer Alan Duffy explained to news.com.au last month. "It's much harder to detect them and we still have not found all the larger asteroids yet."
He called for more funds to be allocated to monitoring systems, stating that "it is only a matter of time before one of these explosions occurs in a city and causes incredible damage."
During a keynote address at the opening of the Planetary Defense Conference, NASA administrator Jim Bridenstine warned that preparing for the impact of an asteroid is something that needs to be taken very seriously.
"We have to make sure people understand that this is not about Hollywood, it's not about movies. It's basically about protecting the only planet we know, right now, to welcome life, and that's the planet Earth, "he said.
"These events are not rare, they happen."
If you are a fan of space, you can follow the NASA Planetary Defense Conference below.