Top 10 Closest Asteroid Flybys in History: Understanding the Near Misses

Updated on August 25, 2025 | By Jameswebb Discovery Editorial Team 

A thrilling look at the space rocks that came shockingly close to our planet — and what they teach us about cosmic dangers and discoveries.

Introduction: When the Sky Nearly Falls

Imagine looking up at the night sky, unaware that a cosmic boulder the size of a house — or even a football field — is rushing past Earth at tens of thousands of miles per hour. Most of the time, these asteroids slip by unnoticed until astronomers sound the alarm days or even hours before their flyby. These encounters, known as closest asteroid flybys, are reminders that our planet orbits through a cosmic shooting gallery.

Asteroids are the leftovers of the early solar system, rocky fragments that never coalesced into planets. While most stay in the asteroid belt between Mars and Jupiter, some — called Near-Earth Objects (NEOs) — wander into Earth’s neighborhood. NASA’s Center for Near Earth Object Studies (CNEOS) and observatories worldwide keep a constant watch on these visitors.

Why? Because even a relatively small asteroid — say, 50 meters wide — could devastate a city if it struck. The Chelyabinsk meteor in 2013 proved this when a 20-meter rock exploded in Earth’s atmosphere, injuring over 1,500 people from shattered glass and shockwaves.

In this article, we’ll take a popular-science journey through the Top 10 Closest Asteroid Flybys in History. We’ll explore the stories behind them, how scientists detected them, what makes each one special, and what they mean for Earth’s future safety.

Let’s count them down — from the “smaller than a bus” rocks to the “skyscraper-sized” monsters that whizzed past us closer than the Moon.

1. 2020 QG – The Record Breaker

On August 16, 2020, a car-sized asteroid named 2020 QG made headlines by buzzing Earth at just 1,830 miles (2,950 km) above the Indian Ocean. To put that into perspective, that’s closer than some satellites!

Discovered by the Zwicky Transient Facility in California just six hours after its closest approach, 2020 QG didn’t pose a danger — it was too small to survive Earth’s atmosphere — but it shattered records. Never before had astronomers documented an asteroid passing this close without hitting us.

Popular science angle: Imagine a rock the size of an SUV, racing past Earth faster than a bullet, and we only noticed after it had already gone. It’s like finding out you almost got rear-ended — but in cosmic terms.

This flyby was a wake-up call about how many small but potentially dangerous space rocks are out there.

2. 2011 CQ1 – The Invisible Visitor

Before 2020 QG, the record holder was 2011 CQ1, another car-sized asteroid that zipped by on February 4, 2011, just 3,400 miles (5,471 km) from Earth’s surface.

Astronomers discovered it only 14 hours before the flyby, once again proving how tricky it is to catch these small, fast movers in time. Though harmless, it gave scientists valuable data: Earth’s gravity actually bent its orbit, altering its future path through space.

Think of it like a cosmic pinball game — Earth acted as the flipper, changing where this asteroid will head next.

3. 2020 VT4 – The One We Missed Until After

If you thought 2020 couldn’t get crazier, meet 2020 VT4. On November 13, 2020, this bus-sized asteroid flew just 240 miles (386 km) above Earth’s surface — lower than the International Space Station!

The catch? Nobody saw it until it was already gone. The asteroid was only spotted 15 hours after its closest approach by the ATLAS survey telescope in Hawaii.

Popular science spin: That’s the space equivalent of a stranger brushing past your shoulder in a crowded subway and you only realizing later. Luckily, if 2020 VT4 had entered our atmosphere, it likely would have broken apart — but the flash and shockwave could have caused serious damage.

4. 2004 FU162 – The Tiny Streak of Light

In March 2004, astronomers tracked 2004 FU162, a small asteroid only 20 feet wide, as it skimmed past Earth at just 4,000 miles (6,500 km).

Though tiny, it was one of the closest approaches ever recorded. If it had hit Earth, it would have exploded in the atmosphere like the Chelyabinsk meteor. Instead, it streaked by safely, providing astronomers with valuable data.

What made this encounter special was timing: unlike many flybys that go unnoticed, this one was tracked before and during the pass, letting scientists watch the action in real time.

5. 2019 OK – The “City Killer” Surprise

In July 2019, a much scarier asteroid nearly caught astronomers off guard. Nicknamed the “City Killer,” 2019 OK measured about 100 meters (330 feet) wide — large enough to destroy a city if it hit.

It flew by at just 45,000 miles (73,000 km) — a cosmic hair’s breadth, barely more than one-fifth the distance to the Moon.

Here’s the chilling part: scientists discovered it only 24 hours before the flyby. Why so late? Its orbit and brightness made it difficult to spot until it was almost on top of us.

This close call sparked debates about asteroid detection funding and technology. If 2019 OK had been on a collision course, there would have been no time to prepare.

6. 2005 YU55 – A Skyscraper-Sized Visitor

On November 8, 2011, asteroid 2005 YU55 — roughly the size of an aircraft carrier (400 meters across) — passed within 201,000 miles (324,000 km) of Earth. That’s closer than the Moon.

This was a major event: NASA tracked it with the Goldstone Radar and even produced detailed 3D models. Unlike the smaller rocks on this list, YU55 was big enough to cause global destruction if it had impacted Earth.

Fortunately, it missed. But for days, astronomers and the public alike followed its journey closely, with headlines about “the asteroid that’s closer than the Moon.”

7. 2005 TN55 – The Halloween Rock

On October 31, 2015, asteroid 2005 TN55 — better known as the “Halloween Asteroid” — passed at a safe distance of about 310,000 miles (500,000 km).

What made it special wasn’t how close it came, but how it looked: radar images revealed it had a skull-like shape. Media dubbed it the “Great Pumpkin” or “Death Comet,” sparking worldwide fascination.

Even though it wasn’t an immediate danger, the Halloween Asteroid shows how close approaches capture public imagination and remind us of the reality of NEOs.

8. 2002 MN – A Sneaky Flyby

On June 14, 2002, asteroid 2002 MN, about 100 meters wide, passed within 75,000 miles (120,000 km) of Earth — just one-third the distance to the Moon.

The kicker? Nobody knew until after it had already gone by.

This was one of the most dangerous close shaves in history. A direct impact would have been catastrophic. The incident fueled a push for more advanced sky surveys, leading to initiatives like NASA’s NEOWISE mission and the upcoming NEO Surveyor spacecraft.

9. Apophis – The Future Threat

No list of close asteroid flybys would be complete without Apophis, one of the most famous potentially hazardous asteroids.

Discovered in 2004, Apophis measures about 370 meters (1,210 feet) across. Early calculations suggested it might strike Earth in 2029 or 2036, sparking global concern.

While later observations ruled out a collision, Apophis will pass within just 19,000 miles (31,000 km) on April 13, 2029 — closer than geostationary satellites. It will be visible to the naked eye across parts of the world.

This flyby is a golden opportunity for science, as astronomers will study how Earth’s gravity tugs on Apophis, refining impact predictions for centuries to come.

10. Chelyabinsk Meteor – The One That Hit

Though not a flyby, the Chelyabinsk meteor deserves a place here because it shows what happens when a close approach turns into an impact.

On February 15, 2013, a 20-meter asteroid exploded over Russia with the energy of about 500 kilotons of TNT — 30 times more powerful than the Hiroshima bomb. Over 1,500 people were injured, mostly from shattered windows.

Chelyabinsk was a sobering reminder that even small asteroids can pack a punch. If it had been just slightly larger, the results could have been far worse.

The Big Picture: Why Closest Asteroid Flybys Matter

Each of these encounters tells a story. Some were tiny space pebbles, harmless but thrilling to track. Others were giant rocks that could have rewritten human history.

For scientists, these flybys are opportunities:

• To test detection systems.

• To refine orbital models.

• To prepare for the day when an asteroid isn’t just passing by.

For the public, they’re a reminder that Earth isn’t isolated. We share space with countless wandering rocks. And while the odds of a civilization-ending impact are low in any given year, they’re not zero.

Planetary Defense: How We’re Getting Ready

So, what happens if we do spot a dangerous asteroid on a collision course?

NASA and international space agencies are developing planetary defense strategies. In 2022, the DART mission successfully nudged the asteroid Dimorphos, proving we can alter an asteroid’s trajectory. Future missions aim to expand this into a robust defense system.

At the same time, new telescopes — like NEO Surveyor — will scan the skies specifically for hazardous asteroids, improving detection years or even decades in advance.

Conclusion: Living in a Cosmic Neighborhood

Asteroids have been striking Earth for billions of years. They shaped our planet, delivered ingredients for life, and caused mass extinctions. They’re part of our cosmic environment.

The closest asteroid flybys in history aren’t just thrilling space stories — they’re reminders that we live in a dynamic solar system. The more we learn, the safer we’ll be.

Next time you look at the night sky, remember: somewhere out there, another space rock is already on its way. The question is, will it just wave hello… or knock on our door?