Asteroid Impact Risk: How Close Are Near Earth Objects and Other Space Threats to Hitting Our Planet?

Earth shares its orbit with countless rocks and icy remnants, yet current monitoring shows no known large asteroid on a direct collision course with the planet. At the same time, the sky is full of smaller near earth objects, and scientists treat asteroid impact risk as a serious but manageable part of modern space threats.

Should People be Worried About Asteroids Hitting Earth?

From an objective standpoint, everyday life is dominated by far more immediate risks than asteroid strikes.

Small objects reach Earth's atmosphere often, yet they usually explode high above the surface or fall as meteorites with limited effects. The large near earth objects capable of global damage are both rare and heavily searched for, which keeps the known risk very low.

Experts tend to frame concern as "appropriate awareness" rather than fear. The risk is non‑zero, but active surveillance and planning mean society is not blind to these space threats.

What Near-Earth Objects are and How They are Tracked

Near earth objects are asteroids or comets whose orbits bring them within about 1.3 astronomical units of the Sun, meaning they pass relatively close to Earth's orbit.

A smaller subset, called potentially hazardous asteroids, have orbits that can come within roughly 4.6 million miles of Earth and are large enough to cause serious regional damage if they struck. These categories help scientists prioritize which objects deserve the closest attention when considering asteroid impact risk.

Global survey networks in the United States, Europe, and other regions scan the sky each night for moving points of light that might be new NEOs.

NASA's Planetary Defense Coordination Office and ESA's NEO programs coordinate follow‑up observations, refine orbits, and maintain public risk lists to track how those space threats evolve over time. Radar observations, when possible, further sharpen estimates of an object's size, shape, and trajectory.

What is a Near‑Earth Object?

In technical terms, a near earth object is simply any small Solar System body, asteroid or comet, whose orbit brings it close to Earth's path around the Sun. This definition does not mean an object is likely to hit the planet; it only indicates that its orbit crosses Earth's neighborhood and is worth tracking.​

What is a Potentially Hazardous Asteroid?

Potentially hazardous asteroids are defined mainly by orbit and size. They have the potential to come within a few million miles of Earth and are typically larger than about 140 meters, big enough that an impact could cause severe regional damage. Being on this list means an asteroid merits close monitoring, not that a collision is expected.

How Close are Known Asteroids to Hitting Earth Right Now?

Risk tables operated by agencies such as ESA list objects with tiny, calculated chances of impact over the coming decades or centuries.

These probabilities often sound dramatic, a one‑in‑tens‑of‑thousands or one‑in‑millions chance, but they usually reflect early uncertainty that shrinks as more observations come in. For most entries, orbit refinements quickly reduce the formal asteroid impact risk to effectively zero.

At present, there is no known asteroid on a confirmed collision course with Earth in the near future. New objects are still being discovered, but the largest kilometer‑scale near earth objects are believed to be mostly cataloged, and none of them is expected to strike the planet in the foreseeable timeline.

Is There an Asteroid That Will Hit Earth?

According to current catalogs, no specific NEO has been identified as a certain impactor. Some objects temporarily appear on risk lists with small impact probabilities, yet nearly all of these are removed once additional data narrows down their paths.

What are the Chances of Earth Being Hit by an Asteroid?

Over long timescales of millions of years, Earth will almost certainly experience further impacts, because it moves through a dynamic Solar System filled with debris.

On human timescales, however, the chance of a civilization‑ending collision is extremely low, while moderate‑sized impacts that could affect a region are more plausible but still rare. This is why monitoring focuses on improving early warning, rather than predicting specific doomsday dates.

What is the Closest an Asteroid Has Come to Earth?

Many news stories highlight "bus‑sized" or "plane‑sized" asteroids passing near Earth, but in most cases these flybys occur at distances greater than the Moon or at least many tens of thousands of kilometers away.

Although the numbers can sound small in astronomical terms, these encounters are safely distant and well outside the range where Earth's gravity would force an unavoidable collision.

How Scientists Measure Asteroid Impact Risk

To communicate risk clearly, researchers use standardized scales. The Torino scale is aimed at the public and ranks impact threats from 0, meaning no risk, up to 10 for a certain, civilization‑threatening collision. Almost all known near earth objects today sit at Torino 0, representing a zero or vanishingly small risk of impact.

Behind the scenes, specialists often rely on the Palermo scale, which compares a specific object's impact likelihood and potential damage to the average background risk from all similar bodies over the same period.

An object can briefly have a slightly positive Palermo rating when first discovered, only to see that value drop once additional data constrains its orbit. These tools help prioritize follow‑up work and ensure that the most concerning candidates get attention first.

Could a Dangerous Asteroid Slip Past our Detectors?

Survey coverage is not perfect, especially for smaller objects and for trajectories that bring an asteroid from the direction of the Sun, where ground‑based telescopes cannot see.

Events like the Chelyabinsk airburst in 2013 demonstrated that city‑scale impacts from tens‑of‑meters‑wide bodies can still surprise observers. For these sizes, the main hazard is localized blast and shockwave damage, not global climate disruption.

For kilometer‑scale near earth objects, the census is much more complete, and ongoing surveys aim to push that completeness even higher. This is why planetary defense agencies emphasize that while surprise events cannot be entirely ruled out, unknown global "Earth‑killer" asteroids are increasingly unlikely.

If an Asteroid was Heading for Earth, What Could be Done?

Modern planetary defense thinking does not stop at detection. If an object with a significant impact probability were found decades in advance, several deflection strategies could, in principle, be used to nudge its orbit slightly so that it misses Earth.​

The DART mission demonstrated that a kinetic impactor can measurably alter the orbit of a small asteroid moon, proving an important concept for future deflection attempts.

Other ideas include gravity tractors, spacecraft that hover nearby and use their own gravitational pull to subtly shift an asteroid's path, along with last‑resort concepts that are less favored due to complexity and risk.

In every scenario, early detection remains the key factor that turns an unmanageable space threat into a solvable engineering problem.

Frequently Asked Questions

1. Can small asteroid impacts affect the climate?

Very small impacts have almost no climate effect; only extremely large impacts that inject huge amounts of dust and aerosols into the atmosphere could measurably cool the planet.

2. How often do scientists update asteroid risk estimates?

Risk estimates are updated whenever new observations come in, sometimes multiple times a year for the same object as its orbit is refined.

3. Do all countries share data on potential asteroid threats?

Most observatories and space agencies share asteroid tracking data openly through international databases so that scientists worldwide can analyze and verify risks.

4. Could asteroid mining change an asteroid's path toward Earth?

In theory, large‑scale mining could alter an asteroid's orbit, but any such activity would be carefully planned and monitored to avoid increasing impact risk.