Most Dangerous Asteroids in History

In an intriguing turn of events, NASA issued a noteworthy alert regarding a massive asteroid named 2024 ON, which was heading towards Earth at breakneck speed. This 720 feet in diameter—more than twice the length of two cricket pitches—made a close pass by our planet on September 15, 2024.

It was observed that it could collide with the Earth, bringing the planet to an end in a disastrous event. Named 2024 ON, this asteroid speeding at 104,761 KMPH missed Earth by 4.4 lunar distances, which is still considered a close pass in astronomical terms.

However, this is not the first time that an asteroid has passed by Earth at a close distance; other asteroids have come even closer without causing any harm. Here is the list of history's top 10 closest asteroid encounters with Earth.

List of the Top 10 Most Dangerous Asteroids in History

According to NASA, here is the list of the top 10 dangerous asteroids that may have close encounters with Earth in the coming years.  

1) Bennu

• Size: a B-type asteroid with a ~500 metre diameter

• Mass: 78 billion kg

Bennu is a near-Earth asteroid that poses a potential impact risk to Earth. Discovered in 1999, it measures about 490 meters (1,640 feet) in diameter and has a mass of approximately 74 million tons (67 million metric tons). It orbits the Sun every 1.2 years.

It is classified as a carbonaceous asteroid, which means it contains organic materials and water-bearing minerals.

It gained significant attention after NASA's OSIRIS-REx mission successfully collected samples from its surface in October 2020 for return to Earth in September 2023.

Bennu is classified as a potentially hazardous asteroid since scientists estimate a 1 in 2,700 chance of Bennu impacting Earth on September 24, 2182.

If it were to collide with our planet, the energy released would be equivalent to 1.4 billion tons of TNT, potentially causing regional devastation.

Scientists study Bennu not only for its potential risks but also because it may provide insights into the early solar system's formation and the origins of organic materials essential for life.

2) 29075 (1950 DA) 

• Size: 1.3 km (1,300 meters)
  

• Mass: 78 million tons (71 million metric tons)

Asteroid (29075) 1950 DA is a mid-sized near-Earth asteroid that has been classified as potentially hazardous due to its orbit crossing Earth's path.

It measures about 1.3 kilometres (0.81 miles) in diameter and has an estimated mass of approximately 78 million tons (71 million metric tons).

It was discovered on 23 February 1950. It was observed for 17 days and then faded from view for half a century. Then, an object discovered on 31 December 2000 was recognised as being the long-lost 1950 DA.

This asteroid measures about 1.3 kilometres across and has been classified as one of the most dangerous asteroids known today because of its possible future impacts on Earth.

Its next close approach will occur on March 16, 2880; however, calculations indicate a low probability—about 1 in 34,500—of collision at that time.

If it were to strike Earth, the energy released would be equivalent to around 75 billion tons of TNT, enough to cause global devastation.

Due to these factors, astronomers continuously monitor this asteroid's trajectory using advanced telescopes and computer simulations to ensure any potential threats are identified well in advance.

3) 2023 TL4 

• Size: 0.33 km (330 meters)
• Mass: 47 million tons (43 million metric tonnes)

Discovered in October 2023, asteroid 2023 TL4 is a newly identified near-Earth object that poses a potential risk due to its size and trajectory.

It measures approximately 330 meters (1,083 feet) in diameter and has an estimated mass of about 47 million tons (43 million metric tons).

Its orbital path brings it close to Earth every few years, with a notable potential impact date set for October 10, 2119. Scientists have estimated a collision risk of about 1 in 181,000 for this date.

If it were to strike Earth, the impact could unleash energy equivalent to about 7.5 billion tons of TNT—150 times more powerful than the Tsar Bomba, the largest nuclear bomb ever detonated.

While this asteroid represents a significant threat, astronomers are actively monitoring its trajectory and studying ways to mitigate potential impacts in the future.

4) Apophis (99942 Apophis)

• Size: 0.34 km (340 meters)

• Mass: 27 million tons (24 million metric tons)

Apophis, designated as (99942 Apophis), is one of the most recognised near-Earth asteroids due to its initial perceived threat level following its discovery in June 2004. It measures approximately 340 metres (1,115 feet) in diameter and has an estimated mass of around 27 million tons (24 million metric tons).

It was initially considered one of the most dangerous asteroids due to its predicted close approaches to Earth. However, further observations have significantly reduced these concerns. Currently, Apophis poses no risk for at least the next century; its closest approach will occur on April 13, 2029. 

During its close approach in 2029, Apophis will pass within about 31,000 kilometres from Earth—closer than many satellites—allowing astronomers to study it closely.

This asteroid serves as an important case study for planetary defence strategies and demonstrates the need for continuous monitoring of near-Earth objects.

5) 2023 DW 

• Size: Approximately estimated at around 50,000 tons

• Mass: Equivalent to about 110 million pounds

2023 DW is a recently discovered near-Earth asteroid that has raised concerns regarding its potential impact risk with Earth. 

Detected early in February 2023 by astronomers using ground-based telescopes, this asteroid measures approximately 50 metres across but has been classified as potentially hazardous due to its close approaches to our planet's orbit over time. 

Initial calculations indicated a small chance—about one in six hundred—of the collision on February 14, 2046; however, ongoing observations have significantly reduced this risk as more data becomes available regarding its trajectory and orbit dynamics. 

While 2023 DW does not pose an immediate threat today, monitoring such asteroids remains crucial for planetary defence efforts against possible future impacts.

6) 1979 XB

• Size: 0.66 km (660 meters)

• Mass: Estimated at around several hundred thousand tons

1979 XB is a near-Earth asteroid that was first observed on December 11, 1979. This asteroid is classified as potentially hazardous due to its size and orbit, which crosses Earth's path. 

It has an estimated diameter of about 660 metres (2,200 feet), making it larger than many other asteroids. It is also classified as potentially hazardous due to its size and orbit.

Its orbit is highly elliptical, taking approximately 3.31 years to complete one revolution around the Sun. At its closest approach, it comes within 0.65 AU of Earth, which is about 97 million kilometres. 

Although it has not been seen since its discovery, scientists have calculated a very low chance—about 1 in 1.8 million—of impacting Earth on December 14, 2113. 

If it were to collide with our planet, the energy released would be equivalent to detonating around 30 billion tons of TNT, highlighting the importance of monitoring such objects for potential threats.

7) 2007 FT3

• Size: 0.21 miles

• Mass: 54 million tonnes

(2007 FT3) is another asteroid classified as potentially hazardous due to its size and orbit around the Sun.  It measures about 340 metres (1,115 feet) across.

Discovered in March 2007 by astronomers at the Catalina Sky Survey in Arizona, this asteroid poses some risk due to its close approaches to Earth. 

While there are no immediate threats from 2007 FT3, it has been noted for its potential future encounters with our planet that could be concerning if not monitored properly. 

The asteroid's orbit brings it relatively close to Earth every few years; hence, astronomers keep track of its trajectory using advanced telescopes and computer models. 

8) Chicxulub Impactor

• Size: Approximately 10-15 km
• Mass: Estimated at several trillion tons

The Chicxulub impactor is one of the most significant asteroids in Earth's history, known for causing the mass extinction event that wiped out the dinosaurs around 66 million years ago. 

This asteroid, estimated to be between 10 and 15 kilometres wide, struck what is now the Yucatán Peninsula in Mexico, creating a massive crater over 150 kilometres in diameter. 

The impact released energy equivalent to 72 trillion tons of TNT, leading to catastrophic consequences. 

It triggered massive wildfires, tsunamis, and a "nuclear winter" effect that blocked sunlight for years, disrupting the climate and food chains. 

This event resulted in the extinction of about 75% of Earth's species. The asteroid is believed to have originated from the outer solar system, specifically as a carbonaceous chondrite.

9) 7482 (1994 PC1)

• Size: 1.1 km (1,100 meters)
• Mass: Estimated at several million tons

Asteroid 7482 (1994 PC1) is a notable near-Earth object that measures approximately 1.1 kilometers (about 3,450 feet) in diameter. Its size makes it larger than 99% of known asteroids, comparable to iconic structures like the Golden Gate Bridge.

This asteroid was discovered in 1994 and is classified as a "Potentially Hazardous Asteroid" due to its orbit crossing Earth's path. It has been closely monitored by NASA and other space agencies to assess any potential risks associated with its future close approaches.

7482 (1994 PC1) completed a safe flyby of Earth on January 18, 2022, passing about 1.2 million miles away, which is over five times the distance to the Moon.

Continuous observations help ensure that any potential threats are identified well in advance, allowing for appropriate planetary defence strategies to be developed if necessary

10) (46610) Bésixdouze

• Size: Estimated around 1.0 x 10^12 kg

• Mass: Equivalent to about 2.2 billion pounds

(46610) Bésixdouze is a notable asteroid, primarily because it is classified as a potentially hazardous object due to its size and orbit. 

Discovered in 1999 by astronomers at the Near-Earth Object Program at NASA's Jet Propulsion Laboratory, Bésixdouze measures approximately 1 kilometre in diameter and has an orbital period of about 3.5 years. 

While it does not currently pose an imminent threat to Earth, its classification draws attention because even small asteroids can cause significant damage if they collide with our planet. 

The name "Bésixdouze" comes from the French phrase for "twelve," which reflects its discovery date—December 12th—while also highlighting the importance of international collaboration in tracking near-Earth objects.

Additional Dangerous Asteroid in the History

11) 2001 WN5

Size:  Approximately 0.9 kilometers (or about 900 meters) in diameter

Mass: Estimated to be several million tons, though an exact figure is not commonly specified in the sources

2001 WN5 is classified as a potentially hazardous asteroid due to its orbit, which crosses that of Earth. It was discovered on November 20, 2001, and has been closely monitored by astronomers. 

NASA JPL has designated 153814 (2001 WN5), a small asteroid whose orbit crosses Earth's orbit, as a "Potentially Hazardous Asteroid" because of its anticipated close pass(es) with Earth.

2001 WN5 orbits the sun every 818 days (2.24 years), coming as close as 0.91 AU and reaching as far as 2.51 AU. With a diameter of about 0.9 kilometres, it is larger than ~97% of asteroids but smaller than large asteroids, comparable in size to the Golden Gate Bridge.

2001 WN5 rotates on its axis every 4.25 hours. The asteroid will make a close approach to Earth on June 26, 2028, passing within approximately 0.65 lunar distances (around 250,000 kilometers).

This close encounter provides an opportunity for further observations and studies to better understand its characteristics and potential risks.