99942 Apophis: Could Earth Be Struck By An Asteroid?

Ethan Wong

September 23, 2022

Around seven years from now, on April 13th, 2029, there is a very unlikely, yet still possible chance that Earth will be hit by an asteroid. 99942 Apophis is an asteroid with a diameter of around 340 meters, and weighing 26 billion kg; the asteroid is calculated to pass by Earth in 2029, as well as possibly in 2036 and 2068. Apophis will remain 19,962 miles from Earth’s surface–in comparison, the Moon is located around 250,000 miles from our planet. If this asteroid ever decides to hit our planet in the future, it would kill millions of people, yet this asteroid is no longer a threat for 2029, and will already be around 5 million miles from Earth by March 30th, 2036.

Astronomers Dave Tholen, Fabrizio Bernardi, and Roy Tucker located in Arizona discovered this asteroid on July 19th, 2004, as they were looking into the sky objects near the Sun. Astronomers observed Apophis’ unique orbit, which was shorter than Earth and most asteroids. The asteroid’s orbit nears the distance of Venus to the Sun, and swings by Earth extremely close. Astronomers classify this asteroid’s orbit to the Aten Asteroid group, which contains possibly hazardous asteroids that maintain proximity to our planet, or less than 1 astronomical unit (Earth being 1 AU from the Sun). As December of 2004 rolled around, astronomers had gathered enough data to support a possible collision with Earth: an unlikely percentage of 2.7%.

By 2006, astronomers were able to determine that Apophis would not hit Earth in 2029, as it would pass by Earth in the Geosynchronous Orbit. This orbit is 35,786 kilometers above the Earth’s surface, classifying it as high-orbit Earth; many satellites are located in this region for different purposes. Although the collision of an asteroid with the Earth is highly unlikely, the gravity of the Earth and other variables in space might ultimately affect the trajectory of the asteroid. One of these variables was studied by astronomers in Hawaii called the Yarkovsky Effect, which essentially can move small asteroids by sunlight. The continuous effects of sunlight on asteroids over many years would generate enough force to overcome the contrasting gravitational forces of the asteroids in orbit. When this occurs, asteroids spinning in a prograde direction would move into a further orbit while asteroids spinning in a retrograde direction would shift into a smaller orbit, closer to the Sun. Although this idea might seem comical at first, an imbalance in the heat radiation of heat of an asteroid could cause an asteroid to lose orbit/change trajectory and end up causing the mass extinction of humans on Earth. 

The likelihood of any asteroid hitting the Earth is extremely unlikely. However, NASA has already come up with creative ways to potentially prevent these rare occurrences before it's too late. The space company has already introduced the Double Asteroid Redirection Test (DART), which is a program designated to impact asteroids that are near Earth, and that could pose a threat to our home With all that in mind, what do you think? Will technology be advanced enough to potentially stop this asteroid if it ever decides to hit Earth, or will humans have to face an Empire State Building-sized asteroid colliding with our home.