NASA's radar gives off a ping, notifying scientists that a world-destroying asteroid has been detected and could hit Earth in 10 years.
World governments are quickly alerted about a potentially catastrophic event, allowing them to formulate a plan to inform the public.
One year before impact, space agencies from every country launch nuclear deflection missiles with hopes of pushing the giant asteroid away from our planet - but the mission fails.
FEMA orders mass evacuations in the impact zone months in advance and the public is told to expect the worst with hours left on the clock.
While NASA has said such a scenario is unlikely to happen in the near future, an asteroid hit Earth this week and was detected only eight hours before impact.
An asteroid hit Earth on Thursday that was detected on eight hours before impact. However, NASA would have about 10 years to save the world from a world-destroying space rock
Most asteroids are not on track to hit Earth - but in the event that one is, here above is the sequence of events that would spring into action after the space rock is spotted
The small space rock that soared over the Philippines on Thursday was only three feet in diameter, which was not large enough to sound any alarms.
A report published by the White House in 2021 recommended that a reconnaissance mission would be necessary if an asteroid measuring at least 165 feet could hit Earth within 50 years is detected.
The document categorized a 3,300-foot-wide asteroid as a 'possible global catastrophe,' a three-mile-wide space rock as 'above the global catastrophe threshold,' and a six-mile-wide object as capable of causing a 'mass extinction.'
However, NASA, FEMA, and the United Nations conducted an exercise in April to assess how prepared Earth would be if a world-destroying asteroid were detected, finding that we would need at least 14 years' notice.
Detecting the world-destroying asteroid - 10 years out
NASA's ground-based telescopes identify the giant asteroid, comparing it with other space rocks in a database to ensure it is newly discovered.
The space agency has several projects that scan the skies, including the Catalina Sky Survey which spotted Thursday's asteroid.
These early-warning systems also include NEOWISE (Near-Earth Object Wide-field Infrared Survey Explorer), a spacecraft equipped with a wide-field, 20-inch infrared telescope that operates in two wavelength ranges.
Once the object is detected, astronomers look at the data for brightness and movement to double-check that it is not a known one.
Teams then report their findings to the Minor Planet Center (MPC), the single worldwide location for reporting asteroids, minor planets and comets.
The MPC and NASA team up to determine the asteroid's orbit to predict if the path poses a threat to Earth.
The team discovers that the space rock is likely to come within five million miles of our planet and sends alerts to other agencies around the world, according to NASA.
Now that the world is aware of the impending threat, space agencies from every country join forces to deflect the asteroid about two years after detection.
A report published by the White House in 2021 categorized asteroid sizes, deeming one at least 3,300 feet wide could be catastrophic
The scenario begins with NASA detecting a world-destroying asteroid 10 years before it hits Earth. The agency has telescopes around the globe, like Catalina Sky Survey in Arizona that detected Thursday's asteroid that hit our planet
Launching an asteroid deflection - two to five years before impact
NASA tested a strategy in 2022 called the Double Asteroid Redirection Test (DART) that plowed into an asteroid at 14,000 miles per hour, leaving a massive plume of dust and rocks, and successfully altering its trajectory.
That asteroid did not threaten our planet, but the space agency could use the strategy to deflect the world-destroying asteroid.
This February, however, NASA's planetary defense chief warned that a DART-like mission would not be able to get off the ground if the impact needed to occur in less than five years.
Leading up to the launch of humanity's Hail Mary, NASA and international partners are studying a range of options, including a spacecraft and nuclear weapons.
The group decides to attack the asteroid with nuclear bombs about five years after detection and begins testing a prototype.
Then, two years before impact, teams send explosives and a detonation device at some short standoff distance from the asteroid.
Kaliat Ramesh, a professor of mechanical engineering and material science at Johns Hopkins University, told VOX: 'We would estimate that it would take energy equivalent to about 200 gigatons of TNT to fully disrupt an asteroid with a 12-mile diameter.'
One gigaton is equal to one billion tons of TNT, which means we would need 10 million Hiroshima-size bombs to destroy the massive asteroid hurtling toward Earth.
The only rockets capable of carrying such massive payloads of nuclear bombs would likely be NASA's Space Launch System (SLS) and Elon Musk's SpaceX Starship, but neither have been proven in this type of mission.
One year before impact, space agencies from every country launch nuclear deflection missiles with hopes of pushing the massive asteroid away from our planet
Billy Bob Thornton as Dan Truman, a a scientist at NASA, in Armageddon. Although a trope of sci-fi films, deflecting asteroids bound for Earth is a real concern
The nuclear option would be faster, a concept familiar to fans of the 1998 film Armageddon, starring Bruce Willis and Ben Affleck.
In the movie, NASA sends a group of deep-sea drillers to blow up an Earth-bound asteroid and save humanity with just 18 days of lead time.
Evacuation Plan - months to hours before impact
In the months leading up to impact, global organizations like the Planetary Defense Coordination Office (PDCO) would create detailed impact scenarios, estimating the destruction radius, atmospheric effects and potential global consequences.
Refined calculations forecasting the exact spot where an asteroid would impact Earth would, however, only become available as the asteroid comes into radar range, a process that new deep-space radar could accelerate.
FEMA would order evacuations around the impact zone to save as many lives as possible
And hours before the asteroid makes impact, the world will be told to shelter-in-place and hope for the best
The information collected by global organizations is sent to FEMA and other emergency groups to alert people in the impact zone, allowing for mass evacuations months before the space rock smashes into Earth.
Teams would also begin formulating rescue plans and assembling relief teams that would be deployed almost immediately after impact to salvage as many lives as possible.
A NASA report published in 2023 estimated that everyone within 300 miles of the impact zone, about 150 million people, 'would need to either evacuate or find an appropriate shelter or build one.'
As the clock ticks down to hours, the public would be ordered to shelter in place while they receiving continuous updates and directions.
After impact
The asteroid impact would cause widespread devastation, triggering tsunamis that devastate coastal regions and massive shockwaves and earthquakes.
Electrical and communication systems around the globe fail almost instantly.
The plan to save Earth would include a deflection strategy, evacuations and shelter-in place
The sun has been blocked by a massive dust plume released from impact, causing a significant drop in temperatures and a 'nuclear winter' that could last for decades.
Earth would be shrouded in darkness as massive fires rage that deplete oxygen levels.
Billions of people are dead, but those who did survive are now suffering from starvation, freezing temperatures and the collapse of civilization’s infrastructure.