It’s a practice run for armageddon.

With 3I/ATLAS days away from making its closest approach to Earth, agencies worldwide are conducting the largest and most extensive planetary defense drill — with the goal of protecting ourselves against future threats from beyond.

“This is an excellent opportunity for observers around the world to practice tracking where a comet is in the sky, should a hazardous comet to Earth ever be found,” NASA representatives told The Post. They cited the fact that we’ve been able to monitor the cosmic interloper for such a long time.

The trial run, which began on Nov. 27 and runs through January 2026, was launched by the International Asteroid Warning Network, a worldwide coalition of space experts, including NASA, the European Space Agency and more than 23 nations.

Their mission is to detect and monitor potentially hazardous asteroids and “near-Earth objects” to assess their possible impacts to our planet.

Thankfully, there is no threat of deep impact from 3I/ATLAS. It will pass within 170 million miles of Earth on Friday before continuing its journey through the cosmos.

Meanwhile, NASA has maintained that the interstellar entity is a comet and not of artificial or extraterrestrial origin, as Harvard scientist Avi Loeb repeatedly speculated, citing unconventional characteristics such as its nongravitational acceleration, anti-tail and bizarre jets — which he believed could be a form of technological thrusters.

Nonetheless, experts believe it’s paramount to monitor our intergalactic visitor to form a blueprint for tracking other potential hazards from deep space.

“Hazards originating in space carry the risk of sudden disaster and potentially derailing everyday life, from natural threats like asteroids and solar storms to the human-made one of space debris,” the ESA said in a statement. “ESA’s Space Safety Programme is dedicated to making sure we can detect, predict and mitigate these space hazards in time.”

In accordance, NASA’s Mars Reconnaissance Orbiter and its HiRISE camera have joined the campaign to keep tabs on ATLAS as it streaks through the cosmos.

Meanwhile, the ESA, which approved a record budget of nearly $30 billion last month, has been honing its forecast by tracking the celestial snowball’s position by analyzing data by terrestrial telescopes in Hawaii, Chile and Australia.

These were pooled with observations from the Mars Express, ExoMars Trace Gas Orbiter and Juice probes in space.

By doing so, they’ve managed to triangulate the comet’s trajectory. However, NASA reps told The Post that “comet observations are challenging for planetary defense purposes because they appear as fuzzy extended objects compared to pointlike asteroids in a telescope’s field of view.”

Meanwhile, the ESA boasts two weapons in the defense efforts against intergalactic hazards, including Meerkat, a 24/7 “automated imminent impactor warning system” whose “primary function is to detect and assess NEOs that pose an immediate likelihood of impacting Earth, typically within the next 30 days.

The other, Aegis, crunches data, orbits of asteroids and comets, to predict risks far into the future, often over the next 100 years.

However, the agencies stressed the need to devise a way to knock the asteroids off their collision course once identified as a threat. In 2022, NASA’s Double Asteroid Redirection Test spacecraft knocked an asteroid called Dimorphos off course by ramming it at high speed.

Loeb has emphasized the importance of bolstering our planetary defenses.

“Most of the real estate is actually out there in the Milky Way galaxy and not on the rock that we all occupy,” he previously told The Post. “Once we realize that there is a neighbor out there that has alien technology, then we might decide at the very least to allocate some portion of the military budgets that we use for the defense of individual nations to use it for the defense of the entire planet.”

He suggested installing a “planetary defense network” composed of an array of spaceships that can monitor and even intercept technological objects bound for Earth.