The Earth Under Constant Threat From Space

Planetary defense: NASA tracks asteroids and meteors

Photo byNASA Hubble Space TelescopeonUnsplash

Every day, the Earth is bombarded by space debris. From tiny grains of sand to objects the size of a car, our planet is under constant assault from asteroids and meteoroids.

known as Near-Earth Objects (NEOs), these objects regularly enter Earth's atmosphere. Most are too small to cause damage, burning up in the atmosphere, creating what we call "shooting stars." However, the larger ones can pose a significant threat to our planet.

NASA’s Near-Earth Object (NEO) Observation Program is constantly tracking potentially hazardous objects that could come close to our planet.

You can visit NASA’s Eyes on Asteroid for a real-time schematic of all the known asteroids currently being tracked.

But they can only monitor the ones they are aware of. Some slip by unnoticed until they come frighteningly close. This was the case with asteroid 2024 ON, a stadium-sized rock that flew past Earth earlier this year. It was only discovered on July 27, 2024.

Traveling at approximately 25 times the speed of sound, 2024 ON passed by our planet at a distance of about 620,000 miles—roughly twice the distance between the Earth and the Moon. While that may seem like a vast distance, in astronomical terms, it is uncomfortably close.

The discovery of 2024 ON triggered a warning from NASA. Had its trajectory been slightly different, the result could have been different. Asteroids of this size, moving at such high speeds, have the potential to cause massive damage if they collide with Earth. (“NASA watches a peanut-shaped asteroid drift past Earth | Phys.org”)

In the coming weeks, another asteroid, discovered on August 7, 2024, is set to come close to Earth. Measuring about 33 feet (10 meters) in diameter, this asteroid will be temporarily captured by Earth’s gravity. While it doesn't pose any threat, its trajectory highlights how a small change in its path could have had dire consequences. Fortunately, by November 25, 2024, this asteroid, named 2024 PT5, will break free of Earth’s orbit and continue on its path around the sun. (“Earth to get an asteroid mini-moon for 2 months | earthsky.org”)

Then there are asteroids like Apophis, discovered in 2004, that have been a cause for concern for decades. This NEO, called a “City Killer” with a diameter of over 1,000 feet, has been closely monitored as it has repeatedly missed our planet by narrow margins.

Apophis has not yet posed an immediate threat. Current data suggests that it will not collide with our planet in the foreseeable future. Nonetheless, it is constantly monitored for any changes in its trajectory. (“Earth Is Safe From Asteroid Apophis | nasa.gov”)

The recent observation of a meteor impact on the Moon by Japanese astronomer Daichi Fujii is an example of the constant threat posed by space debris. While our atmosphere protects us from many small impacts, larger objects could still make their way through. (“Japanese astronomer catches meteorite smashing into the moon| Space.com”)

Every day, the universe takes aim at Earth. While most threats are deflected by the atmosphere or sail harmlessly by, the constant misses by the larger ones—we know about—are a regular occurrence. Earth has so far managed to avoid a catastrophic impact—but the universe isn't done trying.