4 Times Huge Asteroids Came Close to Earth

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We need to get serious about asteroid threats. That's what NASA chief Jim Bridenstine says. The reason?

While researchers say we are not overdue an extinction-level comet impact, and that there are bigger threats to humanity that should be prioritized, the catastrophe that would ensue from an enormous asteroid hitting Earth makes it necessary to have a defense strategy in place.

These asteroids that flew near Earth, and could have caused a catastrophic event if they had collided with us, are proof of why we need to invest in asteroid surveillance and defense.

1. '2019 OK' flies between the Earth and the Moon

The most frightening thing about last year's 2019 OK asteroid flyby is the fact that it caught scientists off guard. According to internal NASA documents obtained by Buzzfeed News, a researcher said: "this one did sneak up on us."

On 25 July 2019, the asteroid, which is the size of a football field, flew between the Earth and the Moon, coming within 65,000 km of our planet’s surface during its closest approach. That brought it to about a fifth of the distance from Earth to the Moon.

2019 OK was only spotted about 24 hours before flying by Earth, meaning we were unaware of its trajectory. If it had hit Earth, "the blast wave could have created localized devastation to an area roughly 50 miles across,” NASA said in a statement.

Highly elliptical orbit of asteroid 2019 OK — The highly elliptical orbit of 2019 OK, *Source: ESA*

“It's no surprise an object like that would take us by surprise,” MIT planetary scientist Richard Binzel told BuzzFeed News. “Our current asteroid search capabilities are not up to the level they should be.”

Scientists behind asteroid surveillance feel their work is currently underfunded, and that they don't have the necessary spacecraft and tools to carry out the job effectively. It's a scary thought.

2. Enormous comet Shoemaker-Levy 9 (SL9) collides with Jupiter

Back in 1994, the collision of Shoemaker-Levy 9 with Jupiter was a reminder for us that large asteroid impacts still happen in our solar system.

While Jupiter has a much higher gravitational pull than Earth, making it act as an asteroid shield of sorts for our planet, there was a very small, but terrifying, chance that Shoemaker-Levy 9 could have impacted Earth instead of passing it by.

This could have caused a global atmospheric disaster, much like the impact event made the dinosaurs go extinct 65 million years ago.

"Shoemaker-Levy 9 was a sort of punch in the gut," Heidi Hammel, who led visible-light observations of the comet with NASA's Hubble Space Telescope, said in a NASA blog post.

animated red image showing diagonal stripes, flash on left side — A recording from NASA’s Infrared Telescope Facility showing Fragment C of the Shoemaker-Levy 9 comet impacting Jupiter in July of 1994, *Source: NASA*

"It really invigorated our understanding of how important it is to monitor our local neighborhood, and to understand what the potential is for impacts on Earth in the future."

In fact, as NASA points out, the collision acted as a wake-up call, leading to the current efforts in planetary defense that we are seeing today. While there was never a serious concern that Shoemaker-Levy 9 would collide with Earth, it serves as a reminder that enormous impacts in our solar system are not confined to the distant past.

3. '2019 GC6' comes a little close for comfort

On April 19 of last year an asteroid named 2019 GC6, a space rock flew past Earth, coming within 219,000 kilometers of Earth. That's slightly more than half the average distance between the Earth and the Moon.

It was traveling at a relative speed of 20,300 km/h and may have been up to 98 feet (30 meters).

Any object that comes within 8 million kilometers of Earth's orbit and is large enough to cause significant damage is classified as a “potentially hazardous” near-Earth object (NEO).

4 Times Huge Asteroids Came Frighteningly Close to Earth — *Source: NASA*

“Near-Earth objects [NEOs] are intrinsically faint because they are mostly really small and far away from us in space. Add to this the fact that some of them are as dark as printer toner, and trying to spot them against the black of space is very hard,” Amy Mainzer, principal investigator of Nasa’s asteroid-hunting mission at NASA's Jet Propulsion Laboratory, told The Independent.

“If we find an object only a few days from impact, it greatly limits our choices, so in our search efforts we’ve focussed on finding NEOs when they are further away from Earth, providing a maximum amount of time and opening up a wider range of mitigation possibilities.”

4. We have to keep an eye on this one

99942 Apophis was discovered in 2004 flying near our planet. While it didn't make a dangerously close approach at the time, it has caused concern amongst scientists due to the close flybys it will make in the future.

In fact, around the time it was discovered, initial calculations of its orbit indicated a 2.7 percent chance of 99942 Apophis impacting Earth during a close approach in 2029.

The asteroid, first labeled as 2004 MN4, is estimated to be roughly 1,000 feet (320 meters) in diameter and would cause huge localized damage if it collided with our planet.

Thankfully, more recent calculations have discredited the initial observations. While Apophis will not hit Earth in 2029, it will come historically close, NASA says. On that date, it will become the closest observed flyby of an asteroid that large when it comes no closer than 19,400 miles (31,300 kilometers) above the Earth's surface.

The asteroid will come so close to Earth that our gravitational pull will alter its trajectory.

It will be a great opportunity for rich scientific observation. The knowledge gained from that flyby will hopefully help scientists better understand asteroids, helping them keep us safer from those rocks hurtling through space.